mirror
/
go
mirror of https://github.com/golang/go.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

runtime: convert prof.hz to atomic type 

This converts several unsynchronized reads (reads without holding
prof.signalLock) into atomic reads.

For #53821.
For #52912.

Change-Id: I421b96a22fbe26d699bcc21010c8a9e0f4efc276
Reviewed-on: https://go-review.googlesource.com/c/go/+/420196
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
This commit is contained in:
Michael Pratt 2022-07-29 14:48:48 -04:00
parent 3121c2bf64
commit 54cf1b107d
3 changed files with 11 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/runtime/cpuprof.go
View File

@ -110,7 +110,7 @@ func (p *cpuProfile) add(tagPtr *unsafe.Pointer, stk []uintptr) {
osyield() osyield()
} }
if prof.hz != 0 { // implies cpuprof.log != nil if prof.hz.Load() != 0 { // implies cpuprof.log != nil
if p.numExtra > 0 || p.lostExtra > 0 || p.lostAtomic > 0 { if p.numExtra > 0 || p.lostExtra > 0 || p.lostAtomic > 0 {
p.addExtra() p.addExtra()
} }

13
src/runtime/proc.go
View File

@ -4475,7 +4475,10 @@ func mcount() int32 {
var prof struct { var prof struct {
signalLock atomic.Uint32 signalLock atomic.Uint32
hz int32
// Must hold signalLock to write. Reads may be lock-free, but
// signalLock should be taken to synchronize with changes.
hz atomic.Int32
} }
func _System() { _System() } func _System() { _System() }
@ -4490,7 +4493,7 @@ func _VDSO() { _VDSO() }
// //
//go:nowritebarrierrec //go:nowritebarrierrec
func sigprof(pc, sp, lr uintptr, gp *g, mp *m) { func sigprof(pc, sp, lr uintptr, gp *g, mp *m) {
if prof.hz == 0 { if prof.hz.Load() == 0 {
return return
} }
@ -4587,7 +4590,7 @@ func sigprof(pc, sp, lr uintptr, gp *g, mp *m) {
} }
} }
if prof.hz != 0 { if prof.hz.Load() != 0 {
// Note: it can happen on Windows that we interrupted a system thread // Note: it can happen on Windows that we interrupted a system thread
// with no g, so gp could nil. The other nil checks are done out of // with no g, so gp could nil. The other nil checks are done out of
// caution, but not expected to be nil in practice. // caution, but not expected to be nil in practice.
@ -4631,9 +4634,9 @@ func setcpuprofilerate(hz int32) {
for !prof.signalLock.CompareAndSwap(0, 1) { for !prof.signalLock.CompareAndSwap(0, 1) {
osyield() osyield()
} }
if prof.hz != hz { if prof.hz.Load() != hz {
setProcessCPUProfiler(hz) setProcessCPUProfiler(hz)
prof.hz = hz prof.hz.Store(hz)
} }
prof.signalLock.Store(0) prof.signalLock.Store(0)

4
src/runtime/signal_unix.go
View File

@ -502,7 +502,7 @@ var sigprofCallersUse uint32
//go:nosplit //go:nosplit
//go:nowritebarrierrec //go:nowritebarrierrec
func sigprofNonGo(sig uint32, info *siginfo, ctx unsafe.Pointer) { func sigprofNonGo(sig uint32, info *siginfo, ctx unsafe.Pointer) {
if prof.hz != 0 { if prof.hz.Load() != 0 {
c := &sigctxt{info, ctx} c := &sigctxt{info, ctx}
// Some platforms (Linux) have per-thread timers, which we use in // Some platforms (Linux) have per-thread timers, which we use in
// combination with the process-wide timer. Avoid double-counting. // combination with the process-wide timer. Avoid double-counting.
@ -525,7 +525,7 @@ func sigprofNonGo(sig uint32, info *siginfo, ctx unsafe.Pointer) {
//go:nosplit //go:nosplit
//go:nowritebarrierrec //go:nowritebarrierrec
func sigprofNonGoPC(pc uintptr) { func sigprofNonGoPC(pc uintptr) {
if prof.hz != 0 { if prof.hz.Load() != 0 {
stk := []uintptr{ stk := []uintptr{
pc, pc,
abi.FuncPCABIInternal(_ExternalCode) + sys.PCQuantum, abi.FuncPCABIInternal(_ExternalCode) + sys.PCQuantum,