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cpuprofiler: drop correct number of signal handler frames 

We actually have 3 and not 2 of them.
This commit is contained in:
Aliaksey Kandratsenka 2014-12-20 19:56:13 -08:00
parent 812ab1ee7e
commit 4859d80205
1 changed files with 10 additions and 9 deletions
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19
src/profiler.cc
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@ -349,19 +349,20 @@ void CpuProfiler::prof_handler(int sig, siginfo_t*, void* signal_ucontext,
// as the "pc" value in the signal handler context.
stack[0] = GetPC(*reinterpret_cast<ucontext_t*>(signal_ucontext));
// We skip the top two stack trace entries (this function and one
// signal handler frame) since they are artifacts of profiling and
// should not be measured. Other profiling related frames may be
// removed by "pprof" at analysis time. Instead of skipping the top
// frames, we could skip nothing, but that would increase the
// profile size unnecessarily.
// We skip the top three stack trace entries (this function,
// SignalHandler::SignalHandler and one signal handler frame)
// since they are artifacts of profiling and should not be
// measured. Other profiling related frames may be removed by
// "pprof" at analysis time. Instead of skipping the top frames,
// we could skip nothing, but that would increase the profile size
// unnecessarily.
int depth = GetStackTraceWithContext(stack + 1, arraysize(stack) - 1,
2, signal_ucontext);
3, signal_ucontext);
void **used_stack;
if (stack[1] == stack[0]) {
// in case of non-frame-pointer-based unwinding we will duplicate
// PC in stack[1], which we don't want
// in case of non-frame-pointer-based unwinding we will get
// duplicate of PC in stack[1], which we don't want
used_stack = stack + 1;
} else {
used_stack = stack;