diff options
Diffstat (limited to 'src/runtime/mprof.go')
| -rw-r--r-- | src/runtime/mprof.go | 46 |
1 files changed, 23 insertions, 23 deletions
diff --git a/src/runtime/mprof.go b/src/runtime/mprof.go index df0f2552af..b51a1ad3ce 100644 --- a/src/runtime/mprof.go +++ b/src/runtime/mprof.go @@ -40,24 +40,6 @@ const ( // size of bucket hash table buckHashSize = 179999 - // maxStack is the max depth of stack to record in bucket. - // Note that it's only used internally as a guard against - // wildly out-of-bounds slicing of the PCs that come after - // a bucket struct, and it could increase in the future. - // The term "1" accounts for the first stack entry being - // taken up by a "skip" sentinel value for profilers which - // defer inline frame expansion until the profile is reported. - // The term "maxSkip" is for frame pointer unwinding, where we - // want to end up with maxLogicalStack frames but will discard - // some "physical" frames to account for skipping. - maxStack = 1 + maxSkip + maxLogicalStack - - // maxLogicalStack is the maximum stack size of a call stack - // to encode in a profile. This counts "logical" frames, which - // includes inlined frames. We may record more than this many - // "physical" frames when using frame pointer unwinding to account - // for deferred handling of skipping frames & inline expansion. - maxLogicalStack = 128 // maxSkip is to account for deferred inline expansion // when using frame pointer unwinding. We record the stack // with "physical" frame pointers but handle skipping "logical" @@ -67,6 +49,11 @@ const ( // This should be at least as large as the largest skip value // used for profiling; otherwise stacks may be truncated inconsistently maxSkip = 5 + + // maxProfStackDepth is the highest valid value for debug.profstackdepth. + // It's used for the bucket.stk func. + // TODO(fg): can we get rid of this? + maxProfStackDepth = 1024 ) type bucketType int @@ -254,10 +241,11 @@ func newBucket(typ bucketType, nstk int) *bucket { return b } -// stk returns the slice in b holding the stack. +// stk returns the slice in b holding the stack. The caller can asssume that the +// backing array is immutable. func (b *bucket) stk() []uintptr { - stk := (*[maxStack]uintptr)(add(unsafe.Pointer(b), unsafe.Sizeof(*b))) - if b.nstk > maxStack { + stk := (*[maxProfStackDepth]uintptr)(add(unsafe.Pointer(b), unsafe.Sizeof(*b))) + if b.nstk > maxProfStackDepth { // prove that slicing works; otherwise a failure requires a P throw("bad profile stack count") } @@ -455,7 +443,7 @@ func mProf_Malloc(mp *m, p unsafe.Pointer, size uintptr) { } // Only use the part of mp.profStack we need and ignore the extra space // reserved for delayed inline expansion with frame pointer unwinding. - nstk := callers(4, mp.profStack[:maxLogicalStack]) + nstk := callers(4, mp.profStack[:debug.profstackdepth]) index := (mProfCycle.read() + 2) % uint32(len(memRecord{}.future)) b := stkbucket(memProfile, size, mp.profStack[:nstk], true) @@ -542,12 +530,18 @@ func blocksampled(cycles, rate int64) bool { // skip should be positive if this event is recorded from the current stack // (e.g. when this is not called from a system stack) func saveblockevent(cycles, rate int64, skip int, which bucketType) { + if debug.profstackdepth == 0 { + // profstackdepth is set to 0 by the user, so mp.profStack is nil and we + // can't record a stack trace. + return + } if skip > maxSkip { print("requested skip=", skip) throw("invalid skip value") } gp := getg() mp := acquirem() // we must not be preempted while accessing profstack + nstk := 1 if tracefpunwindoff() || gp.m.hasCgoOnStack() { mp.profStack[0] = logicalStackSentinel @@ -736,6 +730,12 @@ func (prof *mLockProfile) recordUnlock(l *mutex) { } func (prof *mLockProfile) captureStack() { + if debug.profstackdepth == 0 { + // profstackdepth is set to 0 by the user, so mp.profStack is nil and we + // can't record a stack trace. + return + } + skip := 3 // runtime.(*mLockProfile).recordUnlock runtime.unlock2 runtime.unlockWithRank if staticLockRanking { // When static lock ranking is enabled, we'll always be on the system @@ -780,7 +780,7 @@ func (prof *mLockProfile) store() { mp := acquirem() prof.disabled = true - nstk := maxStack + nstk := int(debug.profstackdepth) for i := 0; i < nstk; i++ { if pc := prof.stack[i]; pc == 0 { nstk = i |