mirror of
https://github.com/LadybirdBrowser/ladybird.git
synced 2024-11-23 08:00:20 +00:00
b32e961a84
The kernel now supports basic profiling of all the threads in a process
by calling profiling_enable(pid_t). You finish the profiling by calling
profiling_disable(pid_t).
This all works by recording thread stacks when the timer interrupt
fires and the current thread is in a process being profiled.
Note that symbolication is deferred until profiling_disable() to avoid
adding more noise than necessary to the profile.
A simple "/bin/profile" command is included here that can be used to
start/stop profiling like so:
$ profile 10 on
... wait ...
$ profile 10 off
After a profile has been recorded, it can be fetched in /proc/profile
There are various limits (or "bugs") on this mechanism at the moment:
- Only one process can be profiled at a time.
- We allocate 8MB for the samples, if you use more space, things will
not work, and probably break a bit.
- Things will probably fall apart if the profiled process dies during
profiling, or while extracing /proc/profile
94 lines
2.6 KiB
C++
94 lines
2.6 KiB
C++
#include <AK/Demangle.h>
|
|
#include <AK/StringBuilder.h>
|
|
#include <Kernel/FileSystem/Custody.h>
|
|
#include <Kernel/KBuffer.h>
|
|
#include <Kernel/Process.h>
|
|
#include <Kernel/Profiling.h>
|
|
#include <LibELF/ELFLoader.h>
|
|
|
|
namespace Profiling {
|
|
|
|
static KBufferImpl* s_profiling_buffer;
|
|
static size_t s_slot_count;
|
|
static size_t s_next_slot_index;
|
|
static Process* s_process;
|
|
|
|
void start(Process& process)
|
|
{
|
|
s_process = &process;
|
|
|
|
if (!s_profiling_buffer) {
|
|
s_profiling_buffer = RefPtr<KBufferImpl>(KBuffer::create_with_size(8 * MB).impl()).leak_ref();
|
|
s_slot_count = s_profiling_buffer->size() / sizeof(Sample);
|
|
}
|
|
|
|
s_next_slot_index = 0;
|
|
}
|
|
|
|
static Sample& sample_slot(size_t index)
|
|
{
|
|
return ((Sample*)s_profiling_buffer->data())[index];
|
|
}
|
|
|
|
Sample& next_sample_slot()
|
|
{
|
|
auto& slot = sample_slot(s_next_slot_index++);
|
|
if (s_next_slot_index >= s_slot_count)
|
|
s_next_slot_index = 0;
|
|
return slot;
|
|
}
|
|
|
|
static void symbolicate(Sample& stack)
|
|
{
|
|
auto& process = *s_process;
|
|
ProcessPagingScope paging_scope(process);
|
|
struct RecognizedSymbol {
|
|
u32 address;
|
|
const KSym* ksym;
|
|
};
|
|
Vector<RecognizedSymbol, max_stack_frame_count> recognized_symbols;
|
|
for (size_t i = 1; i < max_stack_frame_count; ++i) {
|
|
if (stack.frames[i] == 0)
|
|
break;
|
|
recognized_symbols.append({ stack.frames[i], ksymbolicate(stack.frames[i]) });
|
|
}
|
|
|
|
size_t i = 1;
|
|
for (auto& symbol : recognized_symbols) {
|
|
if (!symbol.address)
|
|
break;
|
|
auto& symbol_string_slot = stack.symbolicated_frames[i++];
|
|
if (!symbol.ksym) {
|
|
if (!Scheduler::is_active() && process.elf_loader() && process.elf_loader()->has_symbols())
|
|
symbol_string_slot = String::format("%s", process.elf_loader()->symbolicate(symbol.address).characters());
|
|
else
|
|
symbol_string_slot = String::empty();
|
|
continue;
|
|
}
|
|
unsigned offset = symbol.address - symbol.ksym->address;
|
|
if (symbol.ksym->address == ksym_highest_address && offset > 4096)
|
|
symbol_string_slot = String::empty();
|
|
else
|
|
symbol_string_slot = String::format("%s +%u", demangle(symbol.ksym->name).characters(), offset);
|
|
}
|
|
}
|
|
|
|
void stop()
|
|
{
|
|
for (size_t i = 0; i < s_next_slot_index; ++i) {
|
|
auto& stack = sample_slot(i);
|
|
symbolicate(stack);
|
|
}
|
|
|
|
s_process = nullptr;
|
|
}
|
|
|
|
void for_each_sample(Function<void(Sample&)> callback)
|
|
{
|
|
for (size_t i = 0; i < s_next_slot_index; ++i) {
|
|
auto& sample = sample_slot(i);
|
|
callback(sample);
|
|
}
|
|
}
|
|
|
|
}
|