No perf/semantic changes, merely improves code health.
There were several questions as to why Once.Do uses
atomic.CompareAndSwap to do a store.
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/6208057
This is a follow-up to CL 5978051.
Use kernel cas64 helper if we can, fallback to LDREXD/STREXD if
we are on ARMv6 or higher, and to lock-emulated cas64 if on ARMv5.
A future CL will fix {Add,Load,Store}{Int,Uint}64 and issue 3331.
R=bradfitz, rsc
CC=golang-dev
https://golang.org/cl/6034048
The docs look awkward - there is a paragraph
"For example:" with a plain text example,
and straight below it a real Example.
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/5717048
hammerCompareAndSwapPointer64 was only passing on
little-endian systems. hammerCompareAndSwapPointer32 was
writing 8 bytes to a uint32 value on the heap.
R=rsc, dvyukov
CC=golang-dev
https://golang.org/cl/5654065
Consequently, remove many package Makefiles,
and shorten the few that remain.
gomake becomes 'go tool make'.
Turn off test phases of run.bash that do not work,
flagged with $BROKEN. Future CLs will restore these,
but this seemed like a big enough CL already.
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5601057
An experiment: allow structs to be copied even if they
contain unexported fields. This gives packages the
ability to return opaque values in their APIs, like reflect
does for reflect.Value but without the kludgy hacks reflect
resorts to.
In general, we trust programmers not to do silly things
like *x = *y on a package's struct pointers, just as we trust
programmers not to do unicode.Letter = unicode.Digit,
but packages that want a harder guarantee can introduce
an extra level of indirection, like in the changes to os.File
in this CL or by using an interface type.
All in one CL so that it can be rolled back more easily if
we decide this is a bad idea.
Originally discussed in March 2011.
https://groups.google.com/group/golang-dev/t/3f5d30938c7c45ef
R=golang-dev, adg, dvyukov, r, bradfitz, jan.mercl, gri
CC=golang-dev
https://golang.org/cl/5372095
MFENCE was introduced only on the Pentium4 (SSE2),
while XADD was introduced on the 486.
Fixes#2268.
R=golang-dev, rsc
CC=fshahriar, golang-dev
https://golang.org/cl/5056045
Disable the LoadInt32 and LoadUint32 tests, since they fail.
These should be fixed but we want to get through the rest of the build
to see if something else unrelated is broken. The arm build has been
bad for a long time.
R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4780041
The implementation does not grab the lock,
if Once is already initalized.
Benchmark results on HP Z600 (2 x Xeon E5620, 8 HT cores, 2.40GHz)
are as follows:
benchmark old ns/op new ns/op delta
sync_test.BenchmarkOnce 187.00 14.00 -92.51%
sync_test.BenchmarkOnce-2 909.00 21.40 -97.65%
sync_test.BenchmarkOnce-4 3684.00 20.90 -99.43%
sync_test.BenchmarkOnce-8 5987.00 23.00 -99.62%
sync_test.BenchmarkOnce-16 5051.00 21.60 -99.57%
R=bradfitz, rsc
CC=golang-dev
https://golang.org/cl/4641066
For both contended and uncontended case:
- support arbitrary number of cpus (not just 2)
- dynamic load balancing (improves stability)
- periodic execution of Gosched() to work around non-preemptiviness
For uncontended case eliminates possible false-sharing.
For contended case includes additional variation with some
amount of local work between mutex operations.
R=r, rsc
CC=golang-dev
https://golang.org/cl/4634093
Plus fix spoiling of GOMAXPROCS in 2 existing rwmutex tests.
Plus fix benchmark output to stdout (now it outputs to stderr like all other output).
R=rsc
CC=golang-dev
https://golang.org/cl/4529111
The LDREXD and STREXD instructions require
aligned addresses, and the ARM stack is not
guaranteed to be aligned during the check.
This may cause other problems later (on the ARM
not all 64-bit pointers may be 64-bit aligned)
but at least the check is correct now.
R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/4564053
This changes the internal implementation of Cond so that
it uses two generations of waiters. This enables Signal
to guarantee that it will only wake up waiters that are
currently sleeping at the call time.
Fixes#1648.
R=dvyukov, gustavo, rsc
CC=golang-dev
https://golang.org/cl/4524083
Works around bug in kernel implementation on old ARM5 kernels.
Bug was fixed on 26 Nov 2007 (between 2.6.23 and 2.6.24) but
old kernels persist.
Fixes#1750.
R=dfc, golang-dev
CC=golang-dev
https://golang.org/cl/4436072
go/doc wants to see text after BUG(uid): on the same line
in order to treat it as an official bug comment.
R=gri
CC=golang-dev
https://golang.org/cl/4250043
As discussed in the mailing list, this adds a simple barrier
implementation to the sync package which enables one or more
goroutines to wait for a counter to go down to zero.
R=rsc, rog, r
CC=golang-dev
https://golang.org/cl/3770045
Shenghou Ma
Dmitriy Vyukov
Mikio Hara
Russ Cox
Andrew Gerrand
Evan Shaw
Ian Lance Taylor
Alex Brainman
Rob Pike
Robert Griesemer
Gustavo Niemeyer
Nigel Tao