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Kernel+Profiler: Make profiling per-process and without core dumps

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This patch merges the profiling functionality in the kernel with the
performance events mechanism. A profiler sample is now just another
perf event, rather than a dedicated thing.

Since perf events were already per-process, this now makes profiling
per-process as well.

Processes with perf events would already write out a perfcore.PID file
to the current directory on death, but since we may want to profile
a process and then let it continue running, recorded perf events can
now be accessed at any time via /proc/PID/perf_events.

This patch also adds information about process memory regions to the
perfcore JSON format. This removes the need to supply a core dump to
the Profiler app for symbolication, and so the "profiler coredump"
mechanism is removed entirely.

There's still a hard limit of 4MB worth of perf events per process,
so this is by no means a perfect final design, but it's a nice step
forward for both simplicity and stability.

Fixes #4848
Fixes #4849
This commit is contained in:
Andreas Kling 2021-01-11 09:52:18 +01:00
parent f259d96871
commit 5dafb72370
20 changed files with 195 additions and 310 deletions
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6
Kernel/Thread.cpp
View file

@ -31,8 +31,8 @@
#include <Kernel/Arch/i386/CPU.h>
#include <Kernel/FileSystem/FileDescription.h>
#include <Kernel/KSyms.h>
#include <Kernel/PerformanceEventBuffer.h>
#include <Kernel/Process.h>
#include <Kernel/Profiling.h>
#include <Kernel/Scheduler.h>
#include <Kernel/Thread.h>
#include <Kernel/ThreadTracer.h>
@ -1036,7 +1036,7 @@ Vector<FlatPtr> Thread::raw_backtrace(FlatPtr ebp, FlatPtr eip) const
InterruptDisabler disabler;
auto& process = const_cast<Process&>(this->process());
ProcessPagingScope paging_scope(process);
Vector<FlatPtr, Profiling::max_stack_frame_count> backtrace;
Vector<FlatPtr, PerformanceEvent::max_stack_frame_count> backtrace;
backtrace.append(eip);
FlatPtr stack_ptr_copy;
FlatPtr stack_ptr = (FlatPtr)ebp;
@ -1048,7 +1048,7 @@ Vector<FlatPtr> Thread::raw_backtrace(FlatPtr ebp, FlatPtr eip) const
if (!safe_memcpy(&retaddr, (void*)(stack_ptr + sizeof(FlatPtr)), sizeof(FlatPtr), fault_at))
break;
backtrace.append(retaddr);
if (backtrace.size() == Profiling::max_stack_frame_count)
if (backtrace.size() == PerformanceEvent::max_stack_frame_count)
break;
stack_ptr = stack_ptr_copy;
}