This removes all conditions and conditional code (that I could find)
that depended on darwin/arm.
Fixes#35439 (since that only happened on darwin/arm)
Fixes#37611.
Change-Id: Ia4c32a5a4368ed75231075832b0b5bfb1ad11986
Reviewed-on: https://go-review.googlesource.com/c/go/+/227198
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This removes all files that are only used on darwin/arm and cleans up
build tags in files that are still used on other platforms.
Updates #37611.
Change-Id: Ic9490cf0edfc157c6276a7ca950c1768b34a998f
Reviewed-on: https://go-review.googlesource.com/c/go/+/227197
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
TestPingPongHog tests properties of the scheduler.
But the race detector intentionally does randomized scheduling,
so the test is not applicable.
Fixes#38266
Change-Id: Ib06aa317b2776cb1faa641c4e038e2599cf70b2d
Reviewed-on: https://go-review.googlesource.com/c/go/+/227344
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TestTryAdd is particularly brittle because it tests some real cases by
constructing fake sample stack frames. If those frames don't correctly
represent what the runtime would generate then they may fail to catch
regressions.
Instead, call runtime.Callers at the bottom of real function calls to
generate real frames as a base for truncation, etc in tests. Several of
these tests still have to fake parts of the frames to test the right
thing, but this is a bit less fragile.
Change-Id: I62522a9ded5544b06d1bf28550af5400f3af667b
Reviewed-on: https://go-review.googlesource.com/c/go/+/227484
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
This change adds CFA information to the assembly function 'crosscall1'
and reorgnizes its code to establish well-formed prologue and epilogue.
It will fix an infinite callstack issue when debugging cgo program with
GDB on arm64.
Brief root cause analysis:
GDB's aarch64 unwinder parses prologue to determine current frame's size
and previous PC&SP if CFA information is not available.
The unwinder parses the prologue of 'crosscall1' to determine a frame size
of 0x10, then turns to its next frame trying to compute its previous PC&SP
as they are not saved on current frame's stack as per its 'traditional frame
unwind' rules, which ends up getting an endless frame chain like:
[callee] : pc:<pc0>, sp:<sp0>
crosscall1: pc:<pc1>, sp:<sp0>+0x10
[caller] : pc:<pc1>, sp:<sp0>+0x10+0x10
[caller] : pc:<pc1>, sp:<sp0>+0x10+0x10+0x10
...
GDB fails to detect the 'caller' frame is same as 'crosscall1' and terminate
unwinding since SP increases everytime.
Fixes#37238
Change-Id: Ia6bd8555828541a3a61f7dc9b94dfa00775ec52a
Reviewed-on: https://go-review.googlesource.com/c/go/+/226999
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
I took some of the infrastructure from Austin's lock logging CR
https://go-review.googlesource.com/c/go/+/192704 (with deadlock
detection from the logs), and developed a setup to give static lock
ranking for runtime locks.
Static lock ranking establishes a documented total ordering among locks,
and then reports an error if the total order is violated. This can
happen if a deadlock happens (by acquiring a sequence of locks in
different orders), or if just one side of a possible deadlock happens.
Lock ordering deadlocks cannot happen as long as the lock ordering is
followed.
Along the way, I found a deadlock involving the new timer code, which Ian fixed
via https://go-review.googlesource.com/c/go/+/207348, as well as two other
potential deadlocks.
See the constants at the top of runtime/lockrank.go to show the static
lock ranking that I ended up with, along with some comments. This is
great documentation of the current intended lock ordering when acquiring
multiple locks in the runtime.
I also added an array lockPartialOrder[] which shows and enforces the
current partial ordering among locks (which is embedded within the total
ordering). This is more specific about the dependencies among locks.
I don't try to check the ranking within a lock class with multiple locks
that can be acquired at the same time (i.e. check the ranking when
multiple hchan locks are acquired).
Currently, I am doing a lockInit() call to set the lock rank of most
locks. Any lock that is not otherwise initialized is assumed to be a
leaf lock (a very high rank lock), so that eliminates the need to do
anything for a bunch of locks (including all architecture-dependent
locks). For two locks, root.lock and notifyList.lock (only in the
runtime/sema.go file), it is not as easy to do lock initialization, so
instead, I am passing the lock rank with the lock calls.
For Windows compilation, I needed to increase the StackGuard size from
896 to 928 because of the new lock-rank checking functions.
Checking of the static lock ranking is enabled by setting
GOEXPERIMENT=staticlockranking before doing a run.
To make sure that the static lock ranking code has no overhead in memory
or CPU when not enabled by GOEXPERIMENT, I changed 'go build/install' so
that it defines a build tag (with the same name) whenever any experiment
has been baked into the toolchain (by checking Expstring()). This allows
me to avoid increasing the size of the 'mutex' type when static lock
ranking is not enabled.
Fixes#38029
Change-Id: I154217ff307c47051f8dae9c2a03b53081acd83a
Reviewed-on: https://go-review.googlesource.com/c/go/+/207619
Reviewed-by: Dan Scales <danscales@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Previously we stopped the timer and then reset it. With the current
timer implementation that is no longer required.
Change-Id: Ie7aba61ad53ce835f6fcd0b6bce7fe0a15b10e24
Reviewed-on: https://go-review.googlesource.com/c/go/+/227180
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Loading arguments of Xchg(64) and Xadd(64) functions to registers
could be done only once.
Change-Id: Iaf0a695ec9c6a221dfa755855edb68c476978a5b
Reviewed-on: https://go-review.googlesource.com/c/go/+/227001
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Update race detector syso files for some platforms.
There's still 2 more to do, but they might take a while so I'm
mailing the ones I have now.
Note: some arm64 tests did not complete successfully due to out
of memory errors, but I suspect the .syso is correct.
Update #14481
Update #37485 (I think?)
Update #37355
Change-Id: I7e7e707a1fd7574855a538ba89dc11acc999c760
Reviewed-on: https://go-review.googlesource.com/c/go/+/226981
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
We can initialize the runtime sigqueue packages on first use.
We don't require an explicit initialization step. So, remove it.
Change-Id: I484e02dc2c67395fd5584f35ecda2e28b37168df
Reviewed-on: https://go-review.googlesource.com/c/go/+/226540
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Although duffcopy is not used on PPC64, duff_ppc64x.s and
mkduff.go don't match. Make it so.
Fixes#38188.
Change-Id: Ic6c08e335795ea407880efd449f4229696af7744
Reviewed-on: https://go-review.googlesource.com/c/go/+/226719
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This reverts CL 212767.
Reason for revert: new test is persistently failing on freebsd-arm64-dmgk builder.
Change-Id: Ifd1227628e0e747688ddb4dc580170b2a103a89e
Reviewed-on: https://go-review.googlesource.com/c/go/+/226597
Run-TryBot: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Use explicit names for the error code returned by pollReset
and pollWait, rather than just 0, 1, 2, 3.
Change-Id: I0ab12cae57693deab7cca9cdd2fadd597e23a956
Reviewed-on: https://go-review.googlesource.com/c/go/+/226537
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Recently, the gVisor project needs an instruction's address
with 128 bytes alignment and a function's start address with
2K bytes alignment to fit the architecture requirement for
interrupt table.
This patch allows aligning the address of an instruction to be
aligned to a specific value (2^n and not higher than 2048) and
the address of a function to be 2048 bytes.
The main changes include:
1. Adds ALIGN2048 flag to align a function's address with
2048 bytes.
e.g. "TEXT ·Add(SB),NOSPLIT|ALIGN2048" indicates that the
address of Add function should be aligned to 2048 bytes.
2. Adds a new element in the FuncInfo structure defined in
cmd/internal/obj/link.go file to record the alignment
information.
3. Adds a new element in the Func structure defined in
cmd/internal/goobj/read.go file to read the alignment
information.
4. Because go introduces a new object file format, also add
a new element in the FuncInfo structure defined in
cmd/internal/goobj2/funcinfo.go to record the alignment
information.
5. Adds the assembler support to align an intruction's offset
with a specific value (2^n and not higher than 2048).
e.g. "PCALIGN $256" indicates that the next instruction should
be aligned to 256 bytes.
This CL also adds a test.
Change-Id: I31cfa6fb5bc35dee2c44bf65913e90cddfcb492a
Reviewed-on: https://go-review.googlesource.com/c/go/+/212767
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Currently there are a few sanity checks in the page allocator which
should fail immediately but because it's a check for a negative number
on a uint, it's actually dead-code.
If there's a bug in the page allocator which would cause the sanity
check to fail, this could cause memory corruption by returning an
invalid address (more precisely, one might either see a segfault, or
span overlap).
This change fixes these sanity checks to check the correct condition.
Fixes#38130.
Change-Id: Ia19786cece783d39f26df24dec8788833a6a3f21
Reviewed-on: https://go-review.googlesource.com/c/go/+/226297
Reviewed-by: Giovanni Bajo <rasky@develer.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Instead of calling netpollwakeup, just do the write in netpollBreak.
Use the same signaling we now use in other netpollBreak instances.
Change-Id: I53a65c22862ecc8484aee91d0e1ffb21a9e62d8c
Reviewed-on: https://go-review.googlesource.com/c/go/+/226199
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
This reverts CL 225618.
This is causing TestNetpollBreak to fail on AIX more often than not.
Change-Id: Ia3c24041ead4b320202f7f5b17a6b286f639a689
Reviewed-on: https://go-review.googlesource.com/c/go/+/226198
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
netpollBreak calls netpollwakeup, and netpollwakeup expects the mtxpoll
lock to be held, so that it has exclusive access to pendingUpdates.
Not acquiring the lock was a mistake in CL 171824. Fortunately it
rarely matters in practice.
Change-Id: I32962ec2575c846ef3d6a91a4d821b2ff02d983c
Reviewed-on: https://go-review.googlesource.com/c/go/+/225618
Reviewed-by: Michael Knyszek <mknyszek@google.com>
gentraceback generates PCs which are usually following the CALL
instruction. For those that aren't, it fixes up the PCs so that
functions processing the output can unconditionally decrement the PC.
runtime_expandInlineFrames does this unconditional decrement when
looking up the function. However, the fake stack frame generated for
overflow records fails to meet the contract, and decrementing the PC
results in a PC in the previous function. If that function contains
inlined call, runtime_expandInlineFrames will not short-circuit and will
panic trying to look up a PC that doesn't exist.
Note that the added test does not fail at HEAD. It will only fail (with
a panic) if the function preceeding lostProfileEvent contains inlined
function calls. At the moment (on linux/amd64), that is
runtime/pprof.addMaxRSS, which does not.
Fixes#38096
Change-Id: Iad0819f23c566011c920fd9a5b1254719228da0b
Reviewed-on: https://go-review.googlesource.com/c/go/+/225661
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
Reviewed-by: Heschi Kreinick <heschi@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
There might be some concurrent (maybe not concurrent, just sequential but in a short time window) and duplicate calls to `netpollBreak`, trying to wake up a net-poller. If one has called `netpollBreak` and that waking event hasn't been received by epollwait/kevent/..., then the subsequent calls of `netpollBreak` ought to be ignored or in other words, these calls should be converged into one.
Benchmarks go1.13.5 darwin/amd64:
benchmark-func time/op (old) time/op (new) delta
BenchmarkNetpollBreak-4 29668ns ±1% 3131ns ±2% -89.45%
mem/B (old) mem/B (new) delta
154B ±13% 0B ±0% -100%
Change-Id: I3cf757a5d6edc5a99adad7aea3baee4b7f2a8f5c
GitHub-Last-Rev: 15bcfbab8a
GitHub-Pull-Request: golang/go#36294
Reviewed-on: https://go-review.googlesource.com/c/go/+/212737
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Currently, the capping logic for the GC trigger ratio is such that if
gcpercent is low, we may end up setting the trigger ratio far too high,
breaking the promise of SetGCPercent and GOGC has a trade-off knob (we
won't start a GC early enough, and we will use more memory).
This change modifies the capping logic for the trigger ratio by scaling
the minTriggerRatio with gcpercent the same way we scale
maxTriggerRatio.
Fixes#37927.
Change-Id: I2a048c1808fb67186333d3d5a6bee328be2f35da
Reviewed-on: https://go-review.googlesource.com/c/go/+/223937
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Variable 'procs' used to calculate the threshold of overuse in
TestPhysicalMemoryUtilization should be updated if GOMAXPROCS
gets changed, otherwise the threshold could be a large number,
making the test meaningless.
Change-Id: I876cbf11457529f56bae77af1e35f4538a721f95
Reviewed-on: https://go-review.googlesource.com/c/go/+/210297
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Currently if a goroutine is preempted while owning a timer in the
timerModifying state, it could self-deadlock. When the goroutine is
preempted and calls into the scheduler, it could call checkTimers. If
checkTimers encounters the timerModifying timer and calls runtimer on
it, then runtimer will spin, waiting for that timer to leave the
timerModifying state, which it never will.
So far we got lucky that for the most part that there were no preemption
points while timerModifying is happening, however CL 221077 seems to
have introduced one, leading to sporadic self-deadlocks.
This change disables preemption explicitly while a goroutines holds a
timer in timerModifying. Since only checkTimers (and thus runtimer) is
called from the scheduler, this is sufficient to prevent
preemption-based self-deadlocks.
Fixes#38070.
Updates #37894.
Change-Id: Idbfac310889c92773023733ff7e2ff87e9896f0c
Reviewed-on: https://go-review.googlesource.com/c/go/+/225497
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
newdefer() actually adds the new defer to the current g's defer chain. That
happens even if we are on the system stack, in which case the g will be the g0
stack. For open-coded defers, we call newdefer() (only during panic processing)
while on the system stack, so the new defer is unintentionally added to the
g0._defer defer list. The code later correctly adds the defer to the user g's
defer list.
The g0._defer list is never used. However, that pointer on the g0._defer list can
keep a defer struct alive that is intended to be garbage-collected (smaller defers
use a defer pool, but larger-sized defer records are just GC'ed). freedefer() does
not zero out pointers when it intends that a defer become garbage-collected. So,
we can have the pointers in a defer that is held alive by g0._defer become invalid
(in particular d.link). This is the cause of the bad pointer bug in this issue
The fix is to change newdefer (only used in two places) to not add the new defer
to the gp._defer list. We just do it after the call with the correct gp pointer.
(As mentioned above, this code was already there after the newdefer in
addOneOpenDeferFrame.) That ensures that defers will be correctly
garbage-collected and eliminate the bad pointer.
This fix definitely fixes the original repro. I added a test and tried hard to
reproduce the bug (based on the original repro code), but awasn't actually able to
cause the bug. However, the test is still an interesting mix of heap-allocated,
stack-allocated, and open-coded defers.
Fixes#37688
Change-Id: I1a481b9d9e9b9ba4e8726ef718a1f4512a2d6faf
Reviewed-on: https://go-review.googlesource.com/c/go/+/224581
Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
We used to fall back to GetQueuedCompletionStatus if
GetQueuedCompletionStatus was not available, but as of Go 1.11 we
require Windows 7 or later, so GetQueuedCompletionStatusEx is always
available.
Fixes#37957
Change-Id: I7d8d49a92ab7b1f5afdc54a442f696aaf4a5168e
Reviewed-on: https://go-review.googlesource.com/c/go/+/225059
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Reduce the length of time that other timer functions can see timerModifying.
In particular avoid system calls.
Fixes#38023
Change-Id: I1b61229c668e6085d9ee6dca9488a90055386c36
Reviewed-on: https://go-review.googlesource.com/c/go/+/224902
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
The callers expect negative errno values, so negate them when necessary.
No test because there is no reasonable way to make pipe/pipe2 fail.
This was reported on a system on which pipe2 returned ENOSYS.
Fixes#37997
Change-Id: I3ad6cbbc2521cf495f8df6ec991a3f781122b508
Reviewed-on: https://go-review.googlesource.com/c/go/+/224592
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
This change modifies the implementation of (*mspan).countAlloc by
using OnesCount64 (which on many systems is intrinsified). It does so by
using an unsafe pointer cast, but in this case we don't care about
endianness because we're just counting bits set.
This change means we no longer need the popcnt table which was redundant
in the runtime anyway. We can also simplify the logic here significantly
by observing that mark bits allocations are always 8-byte aligned, so we
don't need to handle any edge-cases due to the fact that OnesCount64
operates on 64 bits at a time: all irrelevant bits will be zero.
Overall, this implementation is significantly faster than the old one on
amd64, and should be similarly faster (or better!) on other systems
which support the intrinsic. On systems which do not, it should be
roughly the same performance because OnesCount64 is implemented using a
table in the general case.
Results on linux/amd64:
name old time/op new time/op delta
MSpanCountAlloc/bits=64-4 16.8ns ± 0% 12.7ns ± 0% -24.40% (p=0.000 n=5+4)
MSpanCountAlloc/bits=128-4 23.5ns ± 0% 12.8ns ± 0% -45.70% (p=0.000 n=4+5)
MSpanCountAlloc/bits=256-4 43.5ns ± 0% 12.8ns ± 0% -70.67% (p=0.000 n=4+5)
MSpanCountAlloc/bits=512-4 59.5ns ± 0% 15.4ns ± 0% -74.12% (p=0.008 n=5+5)
MSpanCountAlloc/bits=1024-4 116ns ± 1% 23ns ± 0% -79.84% (p=0.000 n=5+4)
Change-Id: Id4c994be22224653af5333683a69b0937130ed04
Reviewed-on: https://go-review.googlesource.com/c/go/+/216558
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
This change adds a small microbenchmark for (*mspan).countAlloc, which
we're about to replace. Admittedly this isn't a critical piece of code,
but the benchmark was useful in understanding the performance change.
Change-Id: Iea93c00f571ee95534a42f2ef2ab026b382242b3
Reviewed-on: https://go-review.googlesource.com/c/go/+/224438
Run-TryBot: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
It appears that PowerRegisterSuspendResumeNotification is not supported
when running inside Docker - see issues #35447, #36557 and #37149.
Our current code relies on error number to determine Docker environment.
But we already saw PowerRegisterSuspendResumeNotification return
ERROR_FILE_NOT_FOUND, ERROR_INVALID_PARAMETERS and ERROR_ACCESS_DENIED
(see issues above). So this approach is not sustainable.
Just ignore PowerRegisterSuspendResumeNotification returned error.
Fixes#37149
Change-Id: I2beba9d45cdb8c1efac5e974e747827a6261915a
Reviewed-on: https://go-review.googlesource.com/c/go/+/219657
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>
There are a handful of places where the runtime wants to round up the
result of a division. We just introduced a helper to do this. This CL
replaces all of the hand-coded round-ups (that I could find) with this
helper.
Change-Id: I465d152157ff0f3cad40c0aa57491e4f2de510ad
Reviewed-on: https://go-review.googlesource.com/c/go/+/224385
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
materializeGCProg allocates a temporary buffer for unrolling a GC
program. Unfortunately, when computing the size of the buffer, it
rounds *down* the number of bytes needed to store bitmap before
rounding up the number of pages needed to store those bytes. The fact
that it rounds up to pages usually mitigates the rounding down, but
the type from #37470 exists right on the boundary where this doesn't
work:
type Sequencer struct {
htable [1 << 17]uint32
buf []byte
}
On 64-bit, this GC bitmap is exactly 8 KiB of zeros, followed by three
one bits. Hence, this needs 8193 bytes of storage, but the current
math in materializeGCProg rounds *down* the three one bits to 8192
bytes. Since this is exactly pageSize, the next step of rounding up to
the page size doesn't mitigate this error, and materializeGCProg
allocates a buffer that is one byte too small. runGCProg then writes
one byte past the end of this buffer, causing either a segfault (if
you're lucky!) or memory corruption.
Fixes#37470.
Change-Id: Iad24c463c501cd9b1dc1924bc2ad007991a094a0
Reviewed-on: https://go-review.googlesource.com/c/go/+/221197
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Add a test to ensure that the race detector sees that closing a
channel synchronizes with a read from that channel.
This test case failed when CL 181543 was in the tree.
CL 181543 was reverted in CL 216158; this adds a test to make
sure that we don't re-introduce the problem at a later date.
For #32529
For #36714
Change-Id: I5a40f744c67c3f8191d6ad822710c180880a7375
Reviewed-on: https://go-review.googlesource.com/c/go/+/216099
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
In Go 1.4 we renamed READY to pdReady and WAIT to pdWait as part of
rewriting netpoll from C to Go. Finish updating the comments to use
the new names.
Change-Id: I6cefc698b46c58211fd6be1489bdd70419454962
Reviewed-on: https://go-review.googlesource.com/c/go/+/223998
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This change makes it so that worldsema isn't held across the mark phase.
This means that various operations like ReadMemStats may now stop the
world during the mark phase, reducing latency on such operations.
Only three such operations are still no longer allowed to occur during
marking: GOMAXPROCS, StartTrace, and StopTrace.
For the former it's because any change to GOMAXPROCS impacts GC mark
background worker scheduling and the details there are tricky.
For the latter two it's because tracing needs to observe consistent GC
start and GC end events, and if StartTrace or StopTrace may stop the
world during marking, then it's possible for it to see a GC end event
without a start or GC start event without an end, respectively.
To ensure that GOMAXPROCS and StartTrace/StopTrace cannot proceed until
marking is complete, the runtime now holds a new semaphore, gcsema,
across the mark phase just like it used to with worldsema.
This change is being landed once more after being reverted in the Go
1.14 release cycle, since CL 215157 allows it to have a positive
effect on system performance.
For the benchmark BenchmarkReadMemStatsLatency in the runtime, which
measures ReadMemStats latencies while the GC is exercised, the tail of
these latencies reduced dramatically on an 8-core machine:
name old 50%tile-ns new 50%tile-ns delta
ReadMemStatsLatency-8 4.40M ±74% 0.12M ± 2% -97.35% (p=0.008 n=5+5)
name old 90%tile-ns new 90%tile-ns delta
ReadMemStatsLatency-8 102M ± 6% 0M ±14% -99.79% (p=0.008 n=5+5)
name old 99%tile-ns new 99%tile-ns delta
ReadMemStatsLatency-8 147M ±18% 4M ±57% -97.43% (p=0.008 n=5+5)
Fixes#19812.
Change-Id: If66c3c97d171524ae29f0e7af4bd33509d9fd0bb
Reviewed-on: https://go-review.googlesource.com/c/go/+/216557
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This change adds a benchmark to the runtime which measures ReadMemStats
latencies. It generates allocations with lots of pointers to keep the GC
busy while hitting ReadMemStats and measuring the time it takes to
complete.
Updates #19812.
Change-Id: I7a76aaf497ba5324d3c7a7b3df32461b3e6c3ac8
Reviewed-on: https://go-review.googlesource.com/c/go/+/220177
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Currently, dedicated background mark workers are essentially always
non-preemptible.
This change makes it so that dedicated background mark workers park if
their preemption flag is set and someone is trying to STW, allowing them
to do so.
This change prepares us for allowing a STW to happen (and happen
promptly) during GC marking in a follow-up change.
Updates #19812.
Change-Id: I67fb6085bf0f0aebd18ca500172767818a1f15e3
Reviewed-on: https://go-review.googlesource.com/c/go/+/215157
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Austin Clements <austin@google.com>
If multiple threads call preemptone to preempt the same M, it may
send many signals to the same M such that it hardly make
progress, causing live-lock problem. Only send a signal if there
isn't already one pending.
Fixes#37741.
Change-Id: Id94adb0b95acbd18b23abe637a8dcd81ab41b452
Reviewed-on: https://go-review.googlesource.com/c/go/+/223737
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
In Go 1.13, when the network poller found a list of ready goroutines,
they were added to the global run queue. The timer goroutine would
typically sleep in a futex with a timeout, and when the timeout
expired the timer goroutine would either be handed off to an idle P
or added to the global run queue. The effect was that on a busy system
with no idle P's goroutines waiting for timeouts and goroutines waiting
for the network would start at the same priority.
That changed on tip with the new timer code. Now timer functions are
invoked directly from a P, and it happens that the functions used
by time.Sleep and time.After and time.Ticker add the newly ready
goroutines to the local run queue. When a P looks for work it will
prefer goroutines on the local run queue; in fact it will only
occasionally look at the global run queue, and even when it does it
will just pull one goroutine off. So on a busy system with both active
timers and active network connections the system can noticeably prefer
to run goroutines waiting for timers rather than goroutines waiting
for the network.
This CL undoes that change by, when possible, adding goroutines
waiting for the network to the local run queue of the P that checked.
This doesn't affect network poller checks done by sysmon, but it
does affect network poller checks done as each P enters the scheduler.
This CL also makes injecting a list into either the local or global run
queue more efficient, using bulk operations rather than individual ones.
Change-Id: I85a66ad74e4fc3b458256fb7ab395d06f0d2ffac
Reviewed-on: https://go-review.googlesource.com/c/go/+/216198
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Use instructions in place of currently used defines.
Updates #36765
Change-Id: I00bb59e77b1aace549d7857cc9721ba2cb4ac6ca
Reviewed-on: https://go-review.googlesource.com/c/go/+/220541
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Add support for Load-Reserved (LR) and Store-Conditional (SC) instructions.
Use instructions in place of currently used defines.
Updates #36765
Change-Id: I77e660639802293ece40cfde4865ac237e3308d6
Reviewed-on: https://go-review.googlesource.com/c/go/+/220540
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Also remove #define's that were previously in use.
Updates #36765
Change-Id: I90b6a8629c78f549012f3f6c5f3b325336182712
Reviewed-on: https://go-review.googlesource.com/c/go/+/220539
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Instead, note that mlock has failed, start trying the mitigation of
touching the signal stack before sending a preemption signal, and,
if the program crashes, mention the possible problem and a wiki page
describing the issue (https://golang.org/wiki/LinuxKernelSignalVectorBug).
Tested on a kernel in the buggy version range, but with the patch,
by using `ulimit -l 0`.
Fixes#37436
Change-Id: I072aadb2101496dffd655e442fa5c367dad46ce8
Reviewed-on: https://go-review.googlesource.com/c/go/+/223121
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
This commit extends the -spectre flag to cmd/asm and adds
a new Spectre mitigation mode "ret", which enables the use
of retpolines.
Retpolines prevent speculation about the target of an indirect
jump or call and are described in more detail here:
https://support.google.com/faqs/answer/7625886
Change-Id: I4f2cb982fa94e44d91e49bd98974fd125619c93a
Reviewed-on: https://go-review.googlesource.com/c/go/+/222661
Reviewed-by: Keith Randall <khr@golang.org>
Update error messages for pointer alignment checks and pointer
arithmetic checks so that each type of error has a unique error
message.
Fixes#37488
Change-Id: Ida2c2fa3f041a3307d665879a463f9e8f2c1fd03
Reviewed-on: https://go-review.googlesource.com/c/go/+/223037
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
The cleantimers can run for a while in some unlikely cases.
If the GC is trying to preempt the G, it is forced to wait as the
G is holding timersLock. To avoid introducing a GC delay,
return from cleantimers if the G has a preemption request.
Fixes#37779
Change-Id: Id9a567f991e26668e2292eefc39e2edc56efa4e0
Reviewed-on: https://go-review.googlesource.com/c/go/+/223122
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This test is flaky, and the cause is suspected to be an OpenBSD kernel bug.
Since there is no obvious workaround on the Go side, skip the test on
builders whose versions are known to be affected.
Fixes#17496
Change-Id: Ifa70061eb429e1d949f0fa8a9e25d177afc5c488
Reviewed-on: https://go-review.googlesource.com/c/go/+/222856
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alexander Rakoczy <alex@golang.org>
In the open-code defer implementation, we add defer struct entries to the defer
chain on-the-fly at panic time to represent stack frames that contain open-coded
defers. This allows us to process non-open-coded and open-coded defers in the
correct order. Also, we need somewhere to be able to store the 'started' state of
open-coded defers. However, if a recover succeeds, defers will now be processed
inline again (unless another panic happens). Any defer entry representing a frame
with open-coded defers will become stale once we run the corresponding defers
inline and exit the associated stack frame. So, we need to remove all entries for
open-coded defers at recover time.
The current code was only removing the top-most open-coded defer from the defer
chain during recovery. However, with recursive functions that do repeated
panic-recover-repanic, multiple stale entries can accumulate on the chain. So, we
just adjust the loop to process the entire chain. Since this is at panic/recover
case, it is fine to scan through the entire chain (which should usually have few
elements in it, since most defers are open-coded).
The added test fails with a SEGV without the fix, because it tries to run a stale
open-code defer entry (and the stack has changed).
Fixes#37664.
Change-Id: I8e3da5d610b5e607411451b66881dea887f7484d
Reviewed-on: https://go-review.googlesource.com/c/go/+/222420
Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
If typehash (used by reflect) does not match the built-in map's hash,
then problems occur. If a map is built using reflect, and then
assigned to a variable of map type, the hash function can change. That
causes very bad things.
This issue is rare. MapOf consults a cache of all types that occur in
the binary before making a new one. To make a true new map type (with
a hash function derived from typehash) that map type must not occur in
the binary anywhere. But to cause the bug, we need a variable of that
type in order to assign to it. The only way to make that work is to
use a named map type for the variable, so it is distinct from the
unnamed version that MapOf looks for.
Fixes#37716
Change-Id: I3537bfceca8cbfa1af84202f432f3c06953fe0ed
Reviewed-on: https://go-review.googlesource.com/c/go/+/222357
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
When generating stacks, the runtime automatically expands inline
functions to inline all inline frames in the stack. However, due to the
stack size limit, the final frame may be truncated in the middle of
several inline frames at the same location.
As-is, we assume that the final frame is a normal function, and emit and
cache a Location for it. If we later receive a complete stack frame, we
will first use the cached Location for the inlined function and then
generate a new Location for the "caller" frame, in violation of the
pprof requirement to merge inlined functions into the same Location.
As a result, we:
1. Nondeterministically may generate a profile with the different stacks
combined or split, depending on which is encountered first. This is
particularly problematic when performing a diff of profiles.
2. When split stacks are generated, we lose the inlining information.
We avoid both of these problems by performing a second expansion of the
last stack frame to recover additional inline frames that may have been
lost. This expansion is a bit simpler than the one done by the runtime
because we don't have to handle skipping, and we know that the last
emitted frame is not an elided wrapper, since it by definition is
already included in the stack.
Fixes#37446
Change-Id: If3ca2af25b21d252cf457cc867dd932f107d4c61
Reviewed-on: https://go-review.googlesource.com/c/go/+/221577
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
This was the last remaining use of staticbytes, so we can now
delete it.
The new code appears slightly faster on amd64:
name old time/op new time/op delta
SliceByteToString/1-4 6.29ns ± 2% 5.89ns ± 1% -6.46% (p=0.000 n=14+14)
This may not be the case on the big-endian architectures, since they have
to do an extra addition.
Updates #37612
Change-Id: Icb84c5911ba025f798de152849992a55be99e4f3
Reviewed-on: https://go-review.googlesource.com/c/go/+/221979
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
There are still two places in src/runtime/string.go that use
staticbytes, so we cannot delete it just yet.
There is a new codegen test to verify that the index calculation
is constant-folded, at least on amd64. ppc64, mips[64] and s390x
cannot currently do that.
There is also a new runtime benchmark to ensure that this does not
slow down performance (tested against parent commit):
name old time/op new time/op delta
ConvT2EByteSized/bool-4 1.07ns ± 1% 1.07ns ± 1% ~ (p=0.060 n=14+15)
ConvT2EByteSized/uint8-4 1.06ns ± 1% 1.07ns ± 1% ~ (p=0.095 n=14+15)
Updates #37612
Change-Id: I5ec30738edaa48cda78dfab4a78e24a32fa7fd6a
Reviewed-on: https://go-review.googlesource.com/c/go/+/221957
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Make panics more useful by printing values, if their
underlying kind is printable, instead of just their memory address.
Thus now given any custom type derived from any of:
float*, int*, string, uint*
if we have panic with such a result, its value will be printed.
Thus given any of:
type MyComplex128 complex128
type MyFloat64 float64
type MyString string
type MyUintptr uintptr
panic(MyComplex128(32.1 + 10i))
panic(MyFloat64(-93.7))
panic(MyString("This one"))
panic(MyUintptr(93))
They will now print in the panic:
panic: main.MyComplex64(+1.100000e-001+3.000000e+000i)
panic: main.MyFloat64(-9.370000e+001)
panic: main.MyString("This one")
panic: main.MyUintptr(93)
instead of:
panic: (main.MyComplex128) (0xe0100,0x138cc0)
panic: (main.MyFloat64) (0xe0100,0x138068)
panic: (main.MyString) (0x48aa00,0x4c0840)
panic: (main.MyUintptr) (0xe0100,0x137e58)
and anything else will be printed as in the past with:
panic: (main.MyStruct) (0xe4ee0,0x40a0e0)
Also while here, updated the Go1.15 release notes.
Fixes#37531
Change-Id: Ia486424344a386014f2869ab3483e42a9ef48ac4
Reviewed-on: https://go-review.googlesource.com/c/go/+/221779
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Print the bytes of the instruction that generated a SIGILL.
This should help us respond to bug reports without having to
go back-and-forth with the reporter to get the instruction involved.
Might also help with SIGILL problems that are difficult to reproduce.
Update #37513
Change-Id: I33059b1dbfc97bce16142a843f32a88a6547e280
Reviewed-on: https://go-review.googlesource.com/c/go/+/221431
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
The CGO traceback function is called whenever CGO code is executing and
a signal is received. This occurs much more frequently now SIGURG
is used for preemption.
Disable signal preemption to significantly increase the likelihood that
a signal results in a profile sample during the test.
Updates #37201
Change-Id: Icb1a33ab0754d1a74882a4ee265b4026abe30bdc
Reviewed-on: https://go-review.googlesource.com/c/go/+/219417
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
The error message for an unrecognized type in decodeField was using
string(i) for an int type i. It was recently changed (by me) to
string(rune(i)), but that just avoided a vet warning without fixing
the problem. This CL fixes the problem by using fmt.Errorf.
We also change the message to "unknown wire type" to match the master
copy of this code in github.com/google/pprof/profile/proto.go.
Updates #32479
Change-Id: Ia91ea6d5edbd7cd946225d1ee96bb7623b52bb44
Reviewed-on: https://go-review.googlesource.com/c/go/+/221384
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
If we see a racy use of timers, as in concurrent calls to Timer.Reset,
do the operations in an unpredictable order, rather than crashing.
Fixes#37400
Change-Id: Idbac295df2dfd551b6d762909d5040fc532c1b34
Reviewed-on: https://go-review.googlesource.com/c/go/+/221077
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Instead use string(r) where r has type rune.
This is in preparation for a vet warning for string(i).
Updates #32479
Change-Id: Ic205269bba1bd41723950219ecfb67ce17a7aa79
Reviewed-on: https://go-review.googlesource.com/c/go/+/220844
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Akhil Indurti <aindurti@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Toshihiro Shiino <shiino.toshihiro@gmail.com>
In CL 219131 we inserted a VZEROUPPER instruction on darwin/amd64.
The instruction is not available on pre-AVX machines. Guard it
with CPU feature.
Fixes#37459.
Change-Id: I9a064df277d091be4ee594eda5c7fd8ee323102b
Reviewed-on: https://go-review.googlesource.com/c/go/+/221057
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
In rare circumstances, this helps report a race which would
otherwise go undetected.
Fixes#36794
Change-Id: I8a3c9bd6fc34efa51516393f7ee72531c34fb073
Reviewed-on: https://go-review.googlesource.com/c/go/+/220685
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
This reverts CL 220722.
Reason for revert: rolling forward with fix.
Fixes#37392
Change-Id: Iba8b0c645267777fbb7019976292d691a10b906a
Reviewed-on: https://go-review.googlesource.com/c/go/+/220898
Run-TryBot: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
The wrapper takes a pointer to the argument, not the argument itself.
Fixes#36705
Change-Id: I566d4457d00bf5b84e4a8315a26516975f0d7e10
Reviewed-on: https://go-review.googlesource.com/c/go/+/215942
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Having an mcache field in both m and p is confusing, so remove it from m.
Always use mcache field from p. Use new variable mcache0 during bootstrap.
Change-Id: If2cba9f8bb131d911d512b61fd883a86cf62cc98
Reviewed-on: https://go-review.googlesource.com/c/go/+/205239
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
The runtime implementation of select has an upper limit on the number of
select cases that are supported in order to maintain low stack memory
usage. Rather than support an arbitrary number of select cases, we've
opted to panic early with a useful message pointing the user directly
at the problem.
Fixes#37350
Change-Id: Id129ba281ae120387e681ef96be8adcf89725840
Reviewed-on: https://go-review.googlesource.com/c/go/+/220583
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This constant is only used on libc-based platforms (aix, darwin,
solaris).
Change-Id: Ic57d1fe3b1501c5b552eddb9aba11f1e02510082
Reviewed-on: https://go-review.googlesource.com/c/go/+/220421
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This CL implements Ticker.Reset method in time package.
Benchmark:
name time/op
TickerReset-12 6.41µs ±10%
TickerResetNaive-12 95.7µs ±12%
Fixes#33184
Change-Id: I4cbd31796efa012b2a297bb342158f11a4a31fef
Reviewed-on: https://go-review.googlesource.com/c/go/+/220424
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This reverts CL 217362 (6e5652bebede2d53484a872f6d1dfeb498b0b50c.)
Reason for revert: Causing failures on arm64 bots. See #33184 for more info
Change-Id: I72ba40047e4138767d95aaa68842893c3508c52f
Reviewed-on: https://go-review.googlesource.com/c/go/+/220638
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This CL implements Ticker.Reset method in time package.
Benchmark:
name time/op
TickerReset-12 6.41µs ±10%
TickerResetNaive-12 95.7µs ±12%
Fixes#33184
Change-Id: I12c651f81e452541bcbbc748b45f038aae1f8dae
Reviewed-on: https://go-review.googlesource.com/c/go/+/217362
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
The code has a comment saying that it waited for the goroutines,
but it didn't actually do so.
Change-Id: Icaeb40613711053a9f443cc34143835560427dda
Reviewed-on: https://go-review.googlesource.com/c/go/+/219277
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
On PPC64 when external linking, for large binaries we split the
text section to multiple sections, so the external linking may
insert trampolines between sections. These trampolines are within
the address range covered by the func table, but not known by Go.
This causes runtime.findfunc to return a wrong function if the
given PC is from such trampolines.
In this CL, we generate a marker between text sections where
there could potentially be a hole in the func table. At run time,
we skip the hole if we see such a marker.
Fixes#37216.
Change-Id: I95ab3875a84b357dbaa65a4ed339a19282257ce0
Reviewed-on: https://go-review.googlesource.com/c/go/+/219717
Reviewed-by: David Chase <drchase@google.com>
In walltime1/nanotime1, we save the caller's PC and SP for stack
unwinding. The code does that assumed zero frame size. Now that
the frame size is not zero, correct the offset. Rewrite it in a
way that doesn't depend on hard-coded frame size.
May fix#37127.
Change-Id: I47d6d54fc3499d7d5946c3f6a2dbd24fbd679de1
Reviewed-on: https://go-review.googlesource.com/c/go/+/219118
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Apparently, the signal handling code path in darwin kernel leaves
the upper bits of Y registers in a dirty state, which causes many
SSE operations (128-bit and narrower) become much slower. Clear
the upper bits to get to a clean state.
We do it at the entry of asyncPreempt, which is immediately
following exiting from the kernel's signal handling code, if we
actually injected a call. It does not cover other exits where we
don't inject a call, e.g. failed preemption, profiling signal, or
other async signals. But it does cover an important use case of
async signals, preempting a tight numerical loop, which we
introduced in this cycle.
Running the benchmark in issue #37174:
name old time/op new time/op delta
Fast-8 90.0ns ± 1% 46.8ns ± 3% -47.97% (p=0.000 n=10+10)
Slow-8 188ns ± 5% 49ns ± 1% -73.82% (p=0.000 n=10+9)
There is no more slowdown due to preemption signals.
For #37174.
Change-Id: I8b83d083fade1cabbda09b4bc25ccbadafaf7605
Reviewed-on: https://go-review.googlesource.com/c/go/+/219131
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
We were using the fallback hash unconditionally. Oops.
Fixes#37212
Change-Id: Id37d4f5c08806fdda12a3148ba4dbc46676eeb54
Reviewed-on: https://go-review.googlesource.com/c/go/+/219337
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Otherwise we can see
- goroutine 1 calls netpollBreak, the atomic.Cas succeeds, then suspends
- goroutine 2 calls noteclear, sets netpollBroken to 0
- goroutine 3 calls netpollBreak, the atomic.Cas succeeds, calls notewakeup
- goroutine 1 wakes up calls notewakeup, crashes due to double wakeup
This doesn't happen on Plan 9 because it only runs one thread at a time.
But Fuschia wants to use this code too.
Change-Id: Ib636e4f327bb15e44a2c40fd681aae9a91073a30
Reviewed-on: https://go-review.googlesource.com/c/go/+/218537
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
This commit changes the wording of a comment in malloc.go that describes
how span objects are zeroed to make it more clear.
Change-Id: I07722df1e101af3cbf8680ad07437d4a230b0168
GitHub-Last-Rev: 0e909898c7
GitHub-Pull-Request: golang/go#37008
Reviewed-on: https://go-review.googlesource.com/c/go/+/217618
Reviewed-by: Austin Clements <austin@google.com>
It's possible for the scheduler to try to preempt a goroutine running
on a thread created by C code just as the goroutine returns from Go code
to C code. If that happens, the goroutine will have a nil g,
which would normally cause us to enter the badsignal code.
The badsignal code will allocate an M, reset the signal handler,
and raise the signal. This is all wasted work for SIGURG,
as the default behavior is for the kernel to ignore the signal.
It also means that there is a period of time when preemption requests
are ignored, because the signal handler is reset to the default.
And, finally, it triggers a bug on 386 OpenBSD 6.2. So stop doing it.
No test because there is no real change in behavior (other than on OpenBSD),
the new code is just more efficient
Fixes#36996
Change-Id: I8c1cb9bc09f5ef890cab567924417e2423fc71f6
Reviewed-on: https://go-review.googlesource.com/c/go/+/217617
Reviewed-by: Austin Clements <austin@google.com>
Now that the other dependent offset has been identified, we can remove the
unnecessary ADDI instruction from the riscv64 call sequence (reducing it
to AUIPC+JALR, rather than the previous AUIPC+ADDI+JALR).
Change-Id: I348c4efb686f9f71ed1dd1d25fb9142a41230b0d
Reviewed-on: https://go-review.googlesource.com/c/go/+/216798
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This change formalizes an assumption made by the page allocator, which
is that (*pageAlloc).searchAddr should never refer to memory that is not
represented by (*pageAlloc).inUse. The portion of address space covered
by (*pageAlloc).inUse reflects the parts of the summary arrays which are
guaranteed to mapped, and so looking at any summary which is not
reflected there may cause a segfault.
In fact, this can happen today. This change thus also removes a
micro-optimization which is the only case which may cause
(*pageAlloc).searchAddr to point outside of any region covered by
(*pageAlloc).inUse, and adds a test verifying that the current segfault
can no longer occur.
Change-Id: I98b534f0ffba8656d3bd6d782f6fc22549ddf1c2
Reviewed-on: https://go-review.googlesource.com/c/go/+/216697
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This reverts commit 7b294cdd8d, CL 182657.
Reason for revert: This change may be causing latency problems
for applications which call ReadMemStats, because it may cause
all goroutines to stop until the GC completes.
https://golang.org/cl/215157 fixes this problem, but it's too
late in the cycle to land that.
Updates #19812.
Change-Id: Iaa26f4dec9b06b9db2a771a44e45f58d0aa8f26d
Reviewed-on: https://go-review.googlesource.com/c/go/+/216358
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This reverts commit 05511a5c0a, CL 208379.
Reason for revert: So that we can cleanly revert
https://golang.org/cl/182657.
Change-Id: I4fdf4f864a093db7866b3306f0f8f856b9f4d684
Reviewed-on: https://go-review.googlesource.com/c/go/+/216357
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Unlike C's memmove, Go's memmove must be careful to do indivisible
writes of pointer values because it may be racing with the garbage
collector reading the heap.
We've had various bugs related to this over the years (#36101, #13160,
#12552). Indeed, memmove is a great target for optimization and it's
easy to forget the special requirements of Go's memmove.
The CL documents these (currently unwritten!) requirements. We're also
adding a test that should hopefully keep everyone honest going
forward, though it's hard to be sure we're hitting all cases of
memmove.
Change-Id: I2f59f8d8d6fb42d2f10006b55d605b5efd8ddc24
Reviewed-on: https://go-review.googlesource.com/c/go/+/213418
Reviewed-by: Cherry Zhang <cherryyz@google.com>
The timers code used to have a problem: if code started and stopped a
lot of timers, as would happen with, for example, lots of calls to
context.WithTimeout, then it would steadily use memory holding timers
that had stopped but not been removed from the timer heap.
That problem was fixed by CL 214299, which would remove all deleted
timers whenever they got to be more than 1/4 of the total number of
timers on the heap.
The timers code had a different problem: if there were some idle P's,
the running P's would have lock contention trying to steal their timers.
That problem was fixed by CL 214185, which only acquired the timer lock
if the next timer was ready to run or there were some timers to adjust.
Unfortunately, CL 214185 partially undid 214299, in that we could now
accumulate an increasing number of deleted timers while there were no
timers ready to run. This CL restores the 214299 behavior, by checking
whether there are lots of deleted timers without acquiring the lock.
This is a performance issue to consider for the 1.14 release.
Change-Id: I13c980efdcc2a46eb84882750c39e3f7c5b2e7c3
Reviewed-on: https://go-review.googlesource.com/c/go/+/215722
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
There is a wrong offset when getting the results of a clock_gettime
syscall. Although the syscall will never be called in native ppc64x,
QEMU doesn't implement VDSO, so it will return wrong values.
Fixes#36592
Change-Id: Icf838075228dcdd62cf2c1279aa983e5993d66ee
Reviewed-on: https://go-review.googlesource.com/c/go/+/215397
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Based on riscv-go port.
Updates #27532
Change-Id: If522807a382130be3c8d40f4b4c1131d1de7c9e3
Reviewed-on: https://go-review.googlesource.com/c/go/+/204632
Run-TryBot: Joel Sing <joel@sing.id.au>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Go 1.14 will drop support for macOS 10.10, see #23011
This reverts CL 155097
Updates #26475
Updates #29340
Change-Id: I64d0275141407313b73068436ee81d13eacc4c76
Reviewed-on: https://go-review.googlesource.com/c/go/+/214058
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This reduces lock contention when only a few P's are running and
checking for whether they need to run timers on the sleeping P's.
Without this change the running P's would get lock contention
while looking at the sleeping P's timers. With this change a single
atomic load suffices to determine whether there are any ready timers.
Change-Id: Ie843782bd56df49867a01ecf19c47498ec827452
Reviewed-on: https://go-review.googlesource.com/c/go/+/214185
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: David Chase <drchase@google.com>
Currently, the scavenger is paced according to how long it takes to
scavenge one runtime page's worth of memory. However, this pacing
doesn't take into account the additional cost of actually using a
scavenged page. This operation, "sysUsed," is a counterpart to the
scavenging operation "sysUnused." On most systems this operation is a
no-op, but on some systems like Darwin and Windows we actually make a
syscall. Even on systems where it's a no-op, the cost is implicit: a
more expensive page fault when re-using the page.
On Darwin in particular the cost of "sysUnused" is fairly close to the
cost of "sysUsed", which skews the pacing to be too fast. A lot of
soon-to-be-allocated memory ends up scavenged, resulting in many more
expensive "sysUsed" operations, ultimately slowing down the application.
The way to fix this problem is to include the future cost of "sysUsed"
on a page in the scavenging cost. However, measuring the "sysUsed" cost
directly (like we do with "sysUnused") on most systems is infeasible
because we would have to measure the cost of the first access.
Instead, this change applies a multiplicative constant to the measured
scavenging time which is based on a per-system ratio of "sysUnused" to
"sysUsed" costs in the worst case (on systems where it's a no-op, we
measure the cost of the first access). This ultimately slows down the
scavenger to a more reasonable pace, limiting its impact on performance
but still retaining the memory footprint improvements from the previous
release.
Fixes#36507.
Change-Id: I050659cd8cdfa5a32f5cc0b56622716ea0fa5407
Reviewed-on: https://go-review.googlesource.com/c/go/+/214517
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Whenever more than 1/4 of the timers on a P's heap are deleted,
remove them from the heap.
Change-Id: Iff63ed3d04e6f33ffc5c834f77f645c52c007e52
Reviewed-on: https://go-review.googlesource.com/c/go/+/214299
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
We had a few test cases to make sure checkptr didn't have certain
false positives, but none to test for any true positives. This CL
fixes that.
Updates #22218.
Change-Id: I24c02e469a4af43b1748829a9df325ce510f7cc4
Reviewed-on: https://go-review.googlesource.com/c/go/+/214238
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
When adjustTimers sees a timerModifiedEarlier or timerModifiedLater,
it removes it from the heap, leaving a new timer at that position
in the heap. We were accidentally skipping that new timer in our loop.
In some unlikely cases this could cause adjustTimers to look at more
timers than necessary.
Change-Id: Ic71e54c175ab7d86a7fa46f1497aca71ed1c43cc
Reviewed-on: https://go-review.googlesource.com/c/go/+/214338
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Currently, scavenging information is printed if the gctrace debug
variable is >0. Scavenging information is also printed naively, for
every page scavenged, resulting in a lot of noise when the typical
expectation for GC trace is one line per GC.
This change adds a new GODEBUG flag called scavtrace which prints
scavenge information roughly once per GC cycle and removes any scavenge
information from gctrace. The exception is debug.FreeOSMemory, which may
force an additional line to be printed.
Fixes#32952.
Change-Id: I4177dcb85fe3f9653fd74297ea93c97c389c1811
Reviewed-on: https://go-review.googlesource.com/c/go/+/212640
Run-TryBot: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
On Windows, we implement asynchronous preemption using SuspendThread
to suspend other threads in our process. However, SuspendThread is
itself actually asynchronous (it enqueues a kernel "asynchronous
procedure call" and returns). Unfortunately, Windows' ExitProcess API
kills all threads except the calling one and then runs APCs. As a
result, if SuspendThread and ExitProcess are called simultaneously,
the exiting thread can be suspended and the suspending thread can be
exited, leaving behind a ghost process consisting of a single thread
that's suspended.
We've already protected against the runtime's own calls to
ExitProcess, but if Go code calls external code, there's nothing
stopping that code from calling ExitProcess. For example, in #35775,
our own call to racefini leads to C code calling ExitProcess and
occasionally causing a deadlock.
This CL fixes this by introducing synchronization between calling
external code on Windows and preemption. It adds an atomic field to
the M that participates in a simple CAS-based synchronization protocol
to prevent suspending a thread running external code. We use this to
protect cgocall (which is used for both cgo calls and system calls on
Windows) and racefini.
Tested by running the flag package's TestParse test compiled in race
mode in a loop. Before this change, this would reliably deadlock after
a few minutes.
Fixes#35775.
Updates #10958, #24543.
Change-Id: I50d847abcdc2688b4f71eee6a75eca0f2fee892c
Reviewed-on: https://go-review.googlesource.com/c/go/+/213837
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: David Chase <drchase@google.com>
On Windows, it might be possible that SuspendThread suspends a
thread right between when an exception happens and when the
exception handler runs. (This is my guess. I don't know the
implementation detail of Windows exceptions to be sure.) In this
case, we may inject a call to asyncPreempt before the exception
handler runs. The exception handler will inject a sigpanic call,
which will make the stack trace looks like
sigpanic
asyncPreempt
actual panicking function
i.e. it appears asyncPreempt panicked.
Instead, just overwrite the PC, without pushing another frame.
Fixes#35773.
Change-Id: Ief4e964dcb7f45670b5f93c4dcf285cc1c737514
Reviewed-on: https://go-review.googlesource.com/c/go/+/213879
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
This is more readable and less error-prone than using RSP offsets.
Suggested during review of CL 212765.
Change-Id: I070190abeeac8eae5dbd414407602619d9d57422
Reviewed-on: https://go-review.googlesource.com/c/go/+/213577
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Correct the pipe and pipe2 implementations by using the correct RSP offsets,
used to store and return the file descriptor array.
Fix setNonblock by using the correct immediate value for O_NONBLOCK and
replace EOR (exclusive OR) with ORR.
Also correct the write1 implementation, which has a uintptr value for the fd
argument.
Change-Id: Ibca77af44b649e8bb330ca54f9c36a7a8b0f9cea
Reviewed-on: https://go-review.googlesource.com/c/go/+/212765
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
The current code uses EOR (exclusive OR), which will result in the O_NONBLOCK
flag being toggled rather than being set. Other implementations use OR, hence
this is likely a bug.
Change-Id: I5dafa9c572452070bd37789c8a731ad6d04a86cd
Reviewed-on: https://go-review.googlesource.com/c/go/+/212766
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
In reclaimChunk, the runtime is calling traceGCSweepDone() while holding the mheap
lock. traceGCSweepDone() can call traceEvent() and traceFlush(). These functions
not only can get various trace locks, but they may also do memory allocations
(runtime.newobject) that may end up getting the mheap lock. So, there may be
either a self-deadlock or a possible deadlock between multiple threads.
It seems better to release the mheap lock before calling traceGCSweepDone(). It is
fine to release the lock, since the operations to get the index of the chunk of
work to do are atomic. We already release the lock to call sweep, so there is no
new behavior for any of the callers of reclaimChunk.
With this change, mheap is a leaf lock (no other lock is ever acquired while it
is held).
Testing: besides normal all.bash, also ran all.bash with --long enabled, since
it does longer tests of runtime/trace.
Change-Id: I4f8cb66c24bb8d424f24d6c2305b4b8387409248
Reviewed-on: https://go-review.googlesource.com/c/go/+/207846
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
In the previous CL we ensures that memmove writes pointers
atomically, so the concurrent GC won't observe a partially
updated pointer. This CL adds a test.
Change-Id: Icd1124bf3a15ef25bac20c7fb8933f1a642d897c
Reviewed-on: https://go-review.googlesource.com/c/go/+/212627
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
R11 a.k.a. REGTMP is the temp register used by the assembler. It
may be clobbered if the assembler needs to synthesize
instructions. In particular, in nanotime1/walltime1, the load of
global variable runtime.iscgo clobbers it. So, avoid using R11
to hold a long-lived value.
Fixes#36309.
Change-Id: Iec2ab9d664532cad8fbf58da17f580e64a744f62
Reviewed-on: https://go-review.googlesource.com/c/go/+/212641
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Andrew G. Morgan <agm@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
If a pointer write is not atomic, if the GC is running
concurrently, it may observe a partially updated pointer, which
may point to unallocated or already dead memory. Most pointer
writes, like the store instructions generated by the compiler,
are already atomic. But we still need to be careful in places
like memmove. In memmove, we don't know which bits are pointers
(or too expensive to query), so we ensure that all aligned
pointer-sized units are written atomically.
Fixes#36101.
Change-Id: I1b3ca24c6b1ac8a8aaf9ee470115e9a89ec1b00b
Reviewed-on: https://go-review.googlesource.com/c/go/+/212626
Reviewed-by: Austin Clements <austin@google.com>
When a goroutine yields the remainder of its time to another goroutine
during direct semaphore handoff (as in an Unlock of a sync.Mutex in
starvation mode), it needs to signal that change to the execution
tracer. The discussion in CL 200577 didn't reach consensus on how best
to describe that, but pointed out that "traceEvGoSched / goroutine calls
Gosched" could be confusing.
Emit a "traceEvGoPreempt / goroutine is preempted" event in this case,
to allow the execution tracer to find a consistent event ordering
without being both specific and inaccurate about why the active
goroutine has changed.
Fixes#36186
Change-Id: Ic4ade19325126db2599aff6aba7cba028bb0bee9
Reviewed-on: https://go-review.googlesource.com/c/go/+/211797
Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
This change makes it so that we check whether scavAddr is actually
mapped before trying to look at the summary for the fast path, since we
may segfault if that that part of the summary is not mapped in.
Previously this wasn't a problem because we would conservatively map
all memory for the summaries between the lowest mapped heap address and
the highest one.
This change also adds a test for this case.
Change-Id: I2b1d89b5e044dce81745964dfaba829f4becdc57
Reviewed-on: https://go-review.googlesource.com/c/go/+/212637
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This change disables pageAlloc tests on OpenBSD in short mode because
pageAlloc holds relatively large virtual memory reservations and we make
two during the pageAlloc tests. The runtime may also be carrying one
such reservation making the virtual memory requirement for testing the
Go runtime three times as much as just running a Go binary.
This causes problems for folks who just want to build and test Go
(all.bash) on OpenBSD but either don't have machines with at least 4ish
GiB of RAM (per-process virtual memory limits are capped at some
constant factor times the amount of physical memory) or their
per-process virtual memory limits are low for other reasons.
Fixes#36210.
Change-Id: I8d89cfde448d4cd2fefff4ad6ffed90de63dd527
Reviewed-on: https://go-review.googlesource.com/c/go/+/212177
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Patch up runtime testing to use the libc fcntl function on Darwin,
which is what we should be doing anyhow. This is similar to how
we handle fcntl on AIX and Solaris.
Fixes#36211
Change-Id: I47ad87e11df043ce21496a0d59523dad28960f76
Reviewed-on: https://go-review.googlesource.com/c/go/+/212299
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
nanotime1 and walltime1 do not preserve BP on linux amd64. Previously, this
did not cause a problem, because nanotime/walltime do preserve the BP. But now
with mid-stack inlining, nanotime/walltime are usually inlined, so BP is not
preserved. So, the BP is now wrong in any function after a call to
nanotime()/walltime() on amd64. That means the frame pointer on the stack can
be wrong for any further function call made after the nanotime() call (notably
runtime.main and various GC functions). [386 doesn't use framepointer.]
Fix is to set a frame size of 8 for nanotime1 and walltime1, which means the
standard prolog/epilog that saves/restore BP in the stack frame is added.
I noticed this while investigating issue 16638 (use frame pointers for
runtime.Callers). This change would needed for progress on that issue (which
doesn't have a high priority). Verified that this fix works/is useful for issue
16638.
Change-Id: I19e19ef2c1a517d737a34928baae034f2eb0b2c2
Reviewed-on: https://go-review.googlesource.com/c/go/+/212079
Run-TryBot: Dan Scales <danscales@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
We don't asynchronously preempt if we are in the runtime. We do
this by checking the function name. However, it failed to take
inlining into account. If a runtime function gets inlined into
a non-runtime function, it can be preempted, and bad things can
happen. One instance of this is dounlockOSThread inlined into
UnlockOSThread which is in turn inlined into a non-runtime
function.
Fix this by using the innermost frame's function name.
Change-Id: Ifa036ce1320700aaaefd829b4bee0d04d05c395d
Reviewed-on: https://go-review.googlesource.com/c/go/+/211978
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Systems where PowerRegisterSuspendResumeNotification returns ERROR_
FILE_NOT_FOUND are also systems where nanotime() is on "program time"
rather than "real time". The chain for this is:
powrprof.dll!PowerRegisterSuspendResumeNotification ->
umpdc.dll!PdcPortOpen ->
ntdll.dll!ZwAlpcConnectPort("\\PdcPort") ->
syscall -> ntoskrnl.exe!AlpcpConnectPort
Opening \\.\PdcPort fails with STATUS_OBJECT_NAME_NOT_FOUND when pdc.sys
hasn't been initialized. Pdc.sys also provides the various hooks for
sleep resumption events, which means if it's not loaded, then our "real
time" timer is actually on "program time". Finally STATUS_OBJECT_NAME_
NOT_FOUND is passed through RtlNtStatusToDosError, which returns ERROR_
FILE_NOT_FOUND. Therefore, in the case where the function returns ERROR_
FILE_NOT_FOUND, we don't mind, since the timer we're using will
correspond fine with the lack of sleep resumption notifications. This
applies, for example, to Docker users.
Fixes#35447Fixes#35482
Change-Id: I9e1ce5bbc54b9da55ff7a3918b5da28112647eee
Reviewed-on: https://go-review.googlesource.com/c/go/+/208317
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Jason A. Donenfeld <Jason@zx2c4.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
When growing the address ranges, the new length is the old length + 1.
Fixes#36113.
Change-Id: I1b425f78e473cfa3cbdfe6113e166663f41fc9f3
Reviewed-on: https://go-review.googlesource.com/c/go/+/211157
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
If the defer function pointer is nil, force the seg fault to happen in deferreturn
rather than in jmpdefer. jmpdefer is used fairly infrequently now because most
functions have open-coded defers.
The open-coded defer implementation calls gentraceback() with a callback when
looking for the first open-coded defer frame. gentraceback() throws an error if it
is called with a callback on an LR architecture and jmpdefer is on the stack,
because the stack trace can be incorrect in that case - see issue #8153. So, we
want to make sure that we don't have a seg fault in jmpdefer.
Fixes#36050
Change-Id: Ie25e6f015d8eb170b40248dedeb26a37b7f9b38d
Reviewed-on: https://go-review.googlesource.com/c/go/+/210978
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Prior to this change, if the heap was very discontiguous (such as in
TestArenaCollision) it's possible we could map a large amount of memory
as R/W and commit it. We would use only the start and end to track what
should be mapped, and we would extend that mapping as needed to
accomodate a potentially fragmented address space.
After this change, we only map exactly the part of the summary arrays
that we need by using the inUse ranges from the previous change. This
reduces the GCSys footprint of TestArenaCollision from 300 MiB to 18
MiB.
Because summaries are no longer mapped contiguously, this means the
scavenger can no longer iterate directly. This change also updates the
scavenger to borrow ranges out of inUse and iterate over only the
parts of the heap which are actually currently in use. This is both an
optimization and necessary for correctness.
Fixes#35514.
Change-Id: I96bf0c73ed0d2d89a00202ece7b9d089a53bac90
Reviewed-on: https://go-review.googlesource.com/c/go/+/207758
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
This change adds a new inUse field to the allocator which tracks ranges
of addresses that are owned by the heap. It is updated on each heap
growth.
These ranges are tracked in an array which is kept sorted. In practice
this array shouldn't exceed its initial allocation except in rare cases
and thus should be small (ideally exactly 1 element in size).
In a hypothetical worst-case scenario wherein we have a 1 TiB heap and 4
MiB arenas (note that the address ranges will never be at a smaller
granularity than an arena, since arenas are always allocated
contiguously), inUse would use at most 4 MiB of memory if the heap
mappings were completely discontiguous (highly unlikely) with an
additional 2 MiB leaked from previous allocations. Furthermore, the
copies that are done to keep the inUse array sorted will copy at most 4
MiB of memory in such a scenario, which, assuming a conservative copying
rate of 5 GiB/s, amounts to about 800µs.
However, note that in practice:
1) Most 64-bit platforms have 64 MiB arenas.
2) The copies should incur little-to-no page faults, meaning a copy rate
closer to 25-50 GiB/s is expected.
3) Go heaps are almost always mostly contiguous.
Updates #35514.
Change-Id: I3ad07f1c2b5b9340acf59ecc3b9ae09e884814fe
Reviewed-on: https://go-review.googlesource.com/c/go/+/207757
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Austin Clements <austin@google.com>
The syscall_forkx function returns the value of errno even on success. This can be a problem when using cgo where an atfork handler might be registered; if the atfork handler does something which causes errno to be set the caller of syscall_forkx can be misled into thinking the fork has failed. This causes the various exec functions in the runtime package to hang.
Change-Id: Ia1842179226078a0cbbea33d541aa1187dc47f68
GitHub-Last-Rev: 4dc4db75c8
GitHub-Pull-Request: golang/go#36076
Reviewed-on: https://go-review.googlesource.com/c/go/+/210742
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Support for these was added in CL 189577
Change-Id: Iaf2a774b141995cbbdfb3888aea67ae9c7f928b1
Reviewed-on: https://go-review.googlesource.com/c/go/+/210677
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
After golang.org/cl/210124, I wondered if the same error had gone
unnoticed elsewhere. I quickly spotted another dozen mistakes after
reading through the output of:
git grep '\<[Aa]n [bcdfgjklmnpqrtvwyz][a-z]'
Many results are false positives for acronyms like "an mtime", since
it's pronounced "an em-time". However, the total amount of output isn't
that large given how simple the grep pattern is.
Change-Id: Iaa2ca69e42f4587a9e3137d6c5ed758887906ca6
Reviewed-on: https://go-review.googlesource.com/c/go/+/210678
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Zach Jones <zachj1@gmail.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Austin Clements
Bryan C. Mills
Josh Bleecher Snyder
Keith Randall
Michael Pratt
Ian Lance Taylor
Xiangdong Ji
Dan Scales
maronghe
Cherry Zhang
Richard Miller
fanzha02
Michael Anthony Knyszek
Andy Pan
Meng Zhuo
Ben Schwartz
Alex Brainman
Lynn Boger
Jeremy Faller
Joel Sing
Russ Cox
Johan Jansson
Tamir Duberstein
Diogo Pinela
Emmanuel T Odeke
Mark Pulford
martin
Richard Wilkes
Andrew Bonventre
Milan Patel
Tobias Klauser
Changkun Ou
Andrew Bonventre
Jerrin Shaji George
Draven
Alexander Rakoczy
Carlos Eduardo Seo
Matthew Dempsky
Julian Tibble
Tim Cooper
Rhys Hiltner
Jason A. Donenfeld
Andrew Stormont
Daniel Martí