Version 2.5.2
Improved sampler resolution on Linux.
Allowed forcing the use of a simulator from the build script
independently of the host architecture.
Fixed FreeBSD port (Issue 912).
Made windows-tick-processor respect D8_PATH.
Implemented --noinline-new flag fully on IA32, X64 and ARM platforms.
Review URL: http://codereview.chromium.org/4100005
git-svn-id: http://v8.googlecode.com/svn/trunk@5716 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
diff --git a/src/platform-linux.cc b/src/platform-linux.cc
index c01c0d2..eefaec9 100644
--- a/src/platform-linux.cc
+++ b/src/platform-linux.cc
@@ -33,6 +33,7 @@
#include <signal.h>
#include <sys/time.h>
#include <sys/resource.h>
+#include <sys/syscall.h>
#include <sys/types.h>
#include <stdlib.h>
@@ -714,7 +715,6 @@
#ifdef ENABLE_LOGGING_AND_PROFILING
static Sampler* active_sampler_ = NULL;
-static pthread_t vm_thread_ = 0;
#if !defined(__GLIBC__) && (defined(__arm__) || defined(__thumb__))
@@ -743,36 +743,11 @@
#endif
-// A function that determines if a signal handler is called in the context
-// of a VM thread.
-//
-// The problem is that SIGPROF signal can be delivered to an arbitrary thread
-// (see http://code.google.com/p/google-perftools/issues/detail?id=106#c2)
-// So, if the signal is being handled in the context of a non-VM thread,
-// it means that the VM thread is running, and trying to sample its stack can
-// cause a crash.
-static inline bool IsVmThread() {
- // In the case of a single VM thread, this check is enough.
- if (pthread_equal(pthread_self(), vm_thread_)) return true;
- // If there are multiple threads that use VM, they must have a thread id
- // stored in TLS. To verify that the thread is really executing VM,
- // we check Top's data. Having that ThreadManager::RestoreThread first
- // restores ThreadLocalTop from TLS, and only then erases the TLS value,
- // reading Top::thread_id() should not be affected by races.
- if (ThreadManager::HasId() && !ThreadManager::IsArchived() &&
- ThreadManager::CurrentId() == Top::thread_id()) {
- return true;
- }
- return false;
-}
-
-
static void ProfilerSignalHandler(int signal, siginfo_t* info, void* context) {
#ifndef V8_HOST_ARCH_MIPS
USE(info);
if (signal != SIGPROF) return;
if (active_sampler_ == NULL) return;
- if (!IsVmThread()) return;
TickSample sample_obj;
TickSample* sample = CpuProfiler::TickSampleEvent();
@@ -819,22 +794,51 @@
class Sampler::PlatformData : public Malloced {
public:
- PlatformData() {
- signal_handler_installed_ = false;
+ explicit PlatformData(Sampler* sampler)
+ : sampler_(sampler),
+ signal_handler_installed_(false),
+ vm_tgid_(getpid()),
+ // Glibc doesn't provide a wrapper for gettid(2).
+ vm_tid_(syscall(SYS_gettid)),
+ signal_sender_launched_(false) {
}
+ void SignalSender() {
+ while (sampler_->IsActive()) {
+ // Glibc doesn't provide a wrapper for tgkill(2).
+ syscall(SYS_tgkill, vm_tgid_, vm_tid_, SIGPROF);
+ // Convert ms to us and subtract 100 us to compensate delays
+ // occuring during signal delivery.
+ int result = usleep(sampler_->interval_ * 1000 - 100);
+ ASSERT(result == 0 || errno == EINTR);
+ USE(result);
+ }
+ }
+
+ Sampler* sampler_;
bool signal_handler_installed_;
struct sigaction old_signal_handler_;
- struct itimerval old_timer_value_;
+ int vm_tgid_;
+ int vm_tid_;
+ bool signal_sender_launched_;
+ pthread_t signal_sender_thread_;
};
+static void* SenderEntry(void* arg) {
+ Sampler::PlatformData* data =
+ reinterpret_cast<Sampler::PlatformData*>(arg);
+ data->SignalSender();
+ return 0;
+}
+
+
Sampler::Sampler(int interval, bool profiling)
: interval_(interval),
profiling_(profiling),
synchronous_(profiling),
active_(false) {
- data_ = new PlatformData();
+ data_ = new PlatformData(this);
}
@@ -848,8 +852,6 @@
// platforms.
if (active_sampler_ != NULL) return;
- vm_thread_ = pthread_self();
-
// Request profiling signals.
struct sigaction sa;
sa.sa_sigaction = ProfilerSignalHandler;
@@ -858,31 +860,38 @@
if (sigaction(SIGPROF, &sa, &data_->old_signal_handler_) != 0) return;
data_->signal_handler_installed_ = true;
- // Set the itimer to generate a tick for each interval.
- itimerval itimer;
- itimer.it_interval.tv_sec = interval_ / 1000;
- itimer.it_interval.tv_usec = (interval_ % 1000) * 1000;
- itimer.it_value.tv_sec = itimer.it_interval.tv_sec;
- itimer.it_value.tv_usec = itimer.it_interval.tv_usec;
- setitimer(ITIMER_PROF, &itimer, &data_->old_timer_value_);
+ // Start a thread that sends SIGPROF signal to VM thread.
+ // Sending the signal ourselves instead of relying on itimer provides
+ // much better accuracy.
+ active_ = true;
+ if (pthread_create(
+ &data_->signal_sender_thread_, NULL, SenderEntry, data_) == 0) {
+ data_->signal_sender_launched_ = true;
+ }
// Set this sampler as the active sampler.
active_sampler_ = this;
- active_ = true;
}
void Sampler::Stop() {
+ active_ = false;
+
+ // Wait for signal sender termination (it will exit after setting
+ // active_ to false).
+ if (data_->signal_sender_launched_) {
+ pthread_join(data_->signal_sender_thread_, NULL);
+ data_->signal_sender_launched_ = false;
+ }
+
// Restore old signal handler
if (data_->signal_handler_installed_) {
- setitimer(ITIMER_PROF, &data_->old_timer_value_, NULL);
sigaction(SIGPROF, &data_->old_signal_handler_, 0);
data_->signal_handler_installed_ = false;
}
// This sampler is no longer the active sampler.
active_sampler_ = NULL;
- active_ = false;
}