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Kernel: Prune uninteresting kernel frames from profiling samples

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Start capturing the sample stacks at the EIP/EBP of the pre-empted
thread instead of capturing EBP in the sampling function itself.
This commit is contained in:
Andreas Kling 2021-01-17 10:53:18 +01:00
parent bf0719092f
commit 647cfcb641
Notes: sideshowbarker 2024-07-18 23:08:43 +09:00
3 changed files with 12 additions and 5 deletions
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14
Kernel/PerformanceEventBuffer.cpp
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@ -39,6 +39,16 @@ PerformanceEventBuffer::PerformanceEventBuffer()
}
KResult PerformanceEventBuffer::append(int type, FlatPtr arg1, FlatPtr arg2)
{
FlatPtr ebp;
asm volatile("movl %%ebp, %%eax"
: "=a"(ebp));
auto current_thread = Thread::current();
auto eip = current_thread->get_register_dump_from_stack().eip;
return append_with_eip_and_ebp(eip, ebp, type, arg1, arg2);
}
KResult PerformanceEventBuffer::append_with_eip_and_ebp(u32 eip, u32 ebp, int type, FlatPtr arg1, FlatPtr arg2)
{
if (count() >= capacity())
return KResult(-ENOBUFS);
@ -60,11 +70,7 @@ KResult PerformanceEventBuffer::append(int type, FlatPtr arg1, FlatPtr arg2)
return KResult(-EINVAL);
}
FlatPtr ebp;
asm volatile("movl %%ebp, %%eax"
: "=a"(ebp));
auto current_thread = Thread::current();
auto eip = current_thread->get_register_dump_from_stack().eip;
Vector<FlatPtr> backtrace;
{
SmapDisabler disabler;

1
Kernel/PerformanceEventBuffer.h
View file

@ -61,6 +61,7 @@ public:
PerformanceEventBuffer();
KResult append(int type, FlatPtr arg1, FlatPtr arg2);
KResult append_with_eip_and_ebp(u32 eip, u32 ebp, int type, FlatPtr arg1, FlatPtr arg2);
void clear()
{

2
Kernel/Scheduler.cpp
View file

@ -495,7 +495,7 @@ void Scheduler::timer_tick(const RegisterState& regs)
if (current_thread->process().is_profiling()) {
ASSERT(current_thread->process().perf_events());
auto& perf_events = *current_thread->process().perf_events();
[[maybe_unused]] auto rc = perf_events.append(PERF_EVENT_SAMPLE, 0, 0);
[[maybe_unused]] auto rc = perf_events.append_with_eip_and_ebp(regs.eip, regs.ebp, PERF_EVENT_SAMPLE, 0, 0);
}
if (current_thread->tick((regs.cs & 3) == 0))