* Copyright 2011 Xamarin, Inc (http://www.xamarin.com)
*
* See LICENSE for licensing information.
+ * Licensed under the MIT license. See LICENSE file in the project root for full license information.
*/
#include <config.h>
#include <signal.h>
#include <sys/syscall.h>
#endif
#include <errno.h>
-
+#include <sched.h>
#include <mono/metadata/assembly.h>
#include <mono/metadata/loader.h>
#include <mono/utils/dtrace.h>
#include <mono/utils/mono-signal-handler.h>
#include <mono/utils/mono-threads.h>
+#include <mono/utils/mono-threads-posix-signals.h>
#include "mini.h"
#include <string.h>
#include "jit-icalls.h"
+#ifdef PLATFORM_MACOSX
+#include <mach/mach.h>
+#include <mach/mach_time.h>
+#include <mach/clock.h>
+#endif
+
#if defined(__native_client__) || defined(HOST_WATCHOS)
void
void
mono_runtime_posix_install_handlers(void)
{
-
+ /* we still need to ignore SIGPIPE */
+ signal (SIGPIPE, SIG_IGN);
}
void
#define FULL_STAT_PROFILER_BACKTRACE 0
#endif
-#ifdef SIGPROF
-
-static int profiling_signal_in_use;
-
-#if defined(__ia64__) || defined(__sparc__) || defined(sparc)
-
-MONO_SIG_HANDLER_FUNC (static, sigprof_signal_handler)
-{
- if (mono_chain_signal (MONO_SIG_HANDLER_PARAMS))
- return;
-
- NOT_IMPLEMENTED;
-}
+#if (defined (USE_POSIX_BACKEND) && defined (SIGRTMIN)) || defined (SIGPROF)
+#define HAVE_PROFILER_SIGNAL
+#endif
-#else
+#ifdef HAVE_PROFILER_SIGNAL
static void
per_thread_profiler_hit (void *ctx)
}
}
-MONO_SIG_HANDLER_FUNC (static, sigprof_signal_handler)
+static MonoNativeThreadId sampling_thread;
+
+static gint32 profiler_signals_sent;
+static gint32 profiler_signals_received;
+static gint32 profiler_signals_accepted;
+static gint32 profiler_interrupt_signals_received;
+
+MONO_SIG_HANDLER_FUNC (static, profiler_signal_handler)
{
- MonoThreadInfo *info;
int old_errno = errno;
int hp_save_index;
MONO_SIG_HANDLER_GET_CONTEXT;
+ /* See the comment in mono_runtime_shutdown_stat_profiler (). */
+ if (mono_native_thread_id_get () == sampling_thread) {
+#ifdef HAVE_CLOCK_NANOSLEEP
+ if (mono_profiler_get_sampling_mode () == MONO_PROFILER_STAT_MODE_PROCESS) {
+ InterlockedIncrement (&profiler_interrupt_signals_received);
+ return;
+ }
+#endif
+
+ g_error ("%s: Unexpected profiler signal received by the sampler thread", __func__);
+ }
+
+ InterlockedIncrement (&profiler_signals_received);
+
if (mono_thread_info_get_small_id () == -1)
return; //an non-attached thread got the signal
if (!mono_domain_get () || !mono_native_tls_get_value (mono_jit_tls_id))
return; //thread in the process of dettaching
- hp_save_index = mono_hazard_pointer_save_for_signal_handler ();
-
- /* If we can't consume a profiling request it means we're the initiator. */
- if (!(mono_threads_consume_async_jobs () & MONO_SERVICE_REQUEST_SAMPLE)) {
- FOREACH_THREAD_SAFE (info) {
- if (mono_thread_info_get_tid (info) == mono_native_thread_id_get () ||
- !mono_thread_info_is_live (info))
- continue;
+ InterlockedIncrement (&profiler_signals_accepted);
- mono_threads_add_async_job (info, MONO_SERVICE_REQUEST_SAMPLE);
- mono_threads_pthread_kill (info, profiling_signal_in_use);
- } END_FOREACH_THREAD_SAFE;
- }
+ hp_save_index = mono_hazard_pointer_save_for_signal_handler ();
mono_thread_info_set_is_async_context (TRUE);
per_thread_profiler_hit (ctx);
mono_chain_signal (MONO_SIG_HANDLER_PARAMS);
}
-#endif
#endif
MONO_SIG_HANDLER_FUNC (static, sigquit_signal_handler)
free_saved_signal_handlers ();
}
-#ifdef HAVE_LINUX_RTC_H
-#include <linux/rtc.h>
-#include <sys/ioctl.h>
-#include <fcntl.h>
-static int rtc_fd = -1;
+#ifdef HAVE_PROFILER_SIGNAL
+
+static volatile gint32 sampling_thread_running;
+
+#ifdef PLATFORM_MACOSX
+
+static clock_serv_t sampling_clock_service;
-static int
-enable_rtc_timer (gboolean enable)
+static void
+clock_init (void)
{
- int flags;
- flags = fcntl (rtc_fd, F_GETFL);
- if (flags < 0) {
- perror ("getflags");
- return 0;
- }
- if (enable)
- flags |= FASYNC;
- else
- flags &= ~FASYNC;
- if (fcntl (rtc_fd, F_SETFL, flags) == -1) {
- perror ("setflags");
- return 0;
- }
- return 1;
+ kern_return_t ret;
+
+ do {
+ ret = host_get_clock_service (mach_host_self (), SYSTEM_CLOCK, &sampling_clock_service);
+ } while (ret == KERN_ABORTED);
+
+ if (ret != KERN_SUCCESS)
+ g_error ("%s: host_get_clock_service () returned %d", __func__, ret);
}
-#endif
-void
-mono_runtime_shutdown_stat_profiler (void)
+static void
+clock_cleanup (void)
{
-#ifdef HAVE_LINUX_RTC_H
- if (rtc_fd >= 0)
- enable_rtc_timer (FALSE);
-#endif
+ kern_return_t ret;
+
+ do {
+ ret = mach_port_deallocate (mach_task_self (), sampling_clock_service);
+ } while (ret == KERN_ABORTED);
+
+ if (ret != KERN_SUCCESS)
+ g_error ("%s: mach_port_deallocate () returned %d", __func__, ret);
}
-#ifdef ITIMER_PROF
-static int
-get_itimer_mode (void)
+static guint64
+clock_get_time_ns (void)
{
- switch (mono_profiler_get_sampling_mode ()) {
- case MONO_PROFILER_STAT_MODE_PROCESS: return ITIMER_PROF;
- case MONO_PROFILER_STAT_MODE_REAL: return ITIMER_REAL;
- }
- g_assert_not_reached ();
- return 0;
+ kern_return_t ret;
+ mach_timespec_t mach_ts;
+
+ do {
+ ret = clock_get_time (sampling_clock_service, &mach_ts);
+ } while (ret == KERN_ABORTED);
+
+ if (ret != KERN_SUCCESS)
+ g_error ("%s: clock_get_time () returned %d", __func__, ret);
+
+ return ((guint64) mach_ts.tv_sec * 1000000000) + (guint64) mach_ts.tv_nsec;
+}
+
+static void
+clock_sleep_ns_abs (guint64 ns_abs)
+{
+ kern_return_t ret;
+ mach_timespec_t then, remain_unused;
+
+ then.tv_sec = ns_abs / 1000000000;
+ then.tv_nsec = ns_abs % 1000000000;
+
+ do {
+ ret = clock_sleep (sampling_clock_service, TIME_ABSOLUTE, then, &remain_unused);
+
+ if (ret != KERN_SUCCESS && ret != KERN_ABORTED)
+ g_error ("%s: clock_sleep () returned %d", __func__, ret);
+ } while (ret == KERN_ABORTED && InterlockedRead (&sampling_thread_running));
}
-static int
-get_itimer_signal (void)
+#else
+
+clockid_t sampling_posix_clock;
+
+static void
+clock_init (void)
{
switch (mono_profiler_get_sampling_mode ()) {
- case MONO_PROFILER_STAT_MODE_PROCESS: return SIGPROF;
- case MONO_PROFILER_STAT_MODE_REAL: return SIGALRM;
+ case MONO_PROFILER_STAT_MODE_PROCESS:
+#ifdef HAVE_CLOCK_NANOSLEEP
+ /*
+ * If we don't have clock_nanosleep (), measuring the process time
+ * makes very little sense as we can only use nanosleep () to sleep on
+ * real time.
+ */
+ sampling_posix_clock = CLOCK_PROCESS_CPUTIME_ID;
+ break;
+#endif
+ case MONO_PROFILER_STAT_MODE_REAL: sampling_posix_clock = CLOCK_MONOTONIC; break;
+ default: g_assert_not_reached (); break;
}
- g_assert_not_reached ();
- return 0;
}
+
+static void
+clock_cleanup (void)
+{
+}
+
+static guint64
+clock_get_time_ns (void)
+{
+ struct timespec ts;
+
+ if (clock_gettime (sampling_posix_clock, &ts) == -1)
+ g_error ("%s: clock_gettime () returned -1, errno = %d", __func__, errno);
+
+ return ((guint64) ts.tv_sec * 1000000000) + (guint64) ts.tv_nsec;
+}
+
+static void
+clock_sleep_ns_abs (guint64 ns_abs)
+{
+#ifdef HAVE_CLOCK_NANOSLEEP
+ int ret;
+ struct timespec then;
+
+ then.tv_sec = ns_abs / 1000000000;
+ then.tv_nsec = ns_abs % 1000000000;
+
+ do {
+ ret = clock_nanosleep (sampling_posix_clock, TIMER_ABSTIME, &then, NULL);
+
+ if (ret != 0 && ret != EINTR)
+ g_error ("%s: clock_nanosleep () returned %d", __func__, ret);
+ } while (ret == EINTR && InterlockedRead (&sampling_thread_running));
+#else
+ int ret;
+ gint64 diff;
+ struct timespec req;
+
+ /*
+ * What follows is a crude attempt at emulating clock_nanosleep () on OSs
+ * which don't provide it (e.g. FreeBSD).
+ *
+ * The problem with nanosleep () is that if it is interrupted by a signal,
+ * time will drift as a result of having to restart the call after the
+ * signal handler has finished. For this reason, we avoid using the rem
+ * argument of nanosleep (). Instead, before every nanosleep () call, we
+ * check if enough time has passed to satisfy the sleep request. If yes, we
+ * simply return. If not, we calculate the difference and do another sleep.
+ *
+ * This should reduce the amount of drift that happens because we account
+ * for the time spent executing the signal handler, which nanosleep () is
+ * not guaranteed to do for the rem argument.
+ *
+ * The downside to this approach is that it is slightly expensive: We have
+ * to make an extra system call to retrieve the current time whenever we're
+ * going to restart a nanosleep () call. This is unlikely to be a problem
+ * in practice since the sampling thread won't be receiving many signals in
+ * the first place (it's a tools thread, so no STW), and because typical
+ * sleep periods for the thread are many orders of magnitude bigger than
+ * the time it takes to actually perform that system call (just a few
+ * nanoseconds).
+ */
+ do {
+ diff = (gint64) ns_abs - (gint64) clock_get_time_ns ();
+
+ if (diff <= 0)
+ break;
+
+ req.tv_sec = diff / 1000000000;
+ req.tv_nsec = diff % 1000000000;
+
+ if ((ret = nanosleep (&req, NULL)) == -1 && errno != EINTR)
+ g_error ("%s: nanosleep () returned -1, errno = %d", __func__, errno);
+ } while (ret == -1 && InterlockedRead (&sampling_thread_running));
+#endif
+}
+
#endif
+static int profiler_signal;
+static volatile gint32 sampling_thread_exiting;
+
+static mono_native_thread_return_t
+sampling_thread_func (void *data)
+{
+ mono_threads_attach_tools_thread ();
+ mono_native_thread_set_name (mono_native_thread_id_get (), "Profiler sampler");
+
+ gint64 rate = 1000000000 / mono_profiler_get_sampling_rate ();
+
+ int old_policy;
+ struct sched_param old_sched;
+ pthread_getschedparam (pthread_self (), &old_policy, &old_sched);
+
+ /*
+ * Attempt to switch the thread to real time scheduling. This will not
+ * necessarily work on all OSs; for example, most Linux systems will give
+ * us EPERM here unless configured to allow this.
+ *
+ * TODO: This does not work on Mac (and maybe some other OSs). On Mac, we
+ * have to use the Mach thread policy routines to switch to real-time
+ * scheduling. This is quite tricky as we need to specify how often we'll
+ * be doing work (easy), the normal processing time needed (also easy),
+ * and the maximum amount of processing time needed (hard). This is
+ * further complicated by the fact that if we misbehave and take too long
+ * to do our work, the kernel may knock us back down to the normal thread
+ * scheduling policy without telling us.
+ */
+ struct sched_param sched = { .sched_priority = sched_get_priority_max (SCHED_FIFO) };
+ pthread_setschedparam (pthread_self (), SCHED_FIFO, &sched);
+
+ clock_init ();
+
+ guint64 sleep = clock_get_time_ns ();
+
+ while (InterlockedRead (&sampling_thread_running)) {
+ sleep += rate;
+
+ FOREACH_THREAD_SAFE (info) {
+ /* info should never be this thread as we're a tools thread. */
+ g_assert (mono_thread_info_get_tid (info) != mono_native_thread_id_get ());
+
+ mono_threads_pthread_kill (info, profiler_signal);
+ InterlockedIncrement (&profiler_signals_sent);
+ } FOREACH_THREAD_SAFE_END
+
+ clock_sleep_ns_abs (sleep);
+ }
+
+ InterlockedWrite (&sampling_thread_exiting, 1);
+
+ clock_cleanup ();
+
+ pthread_setschedparam (pthread_self (), old_policy, &old_sched);
+
+ mono_thread_info_detach ();
+
+ return NULL;
+}
+
void
-mono_runtime_setup_stat_profiler (void)
+mono_runtime_shutdown_stat_profiler (void)
{
-#ifdef ITIMER_PROF
- struct itimerval itval;
- static int inited = 0;
-#ifdef HAVE_LINUX_RTC_H
- const char *rtc_freq;
- if (!inited && (rtc_freq = g_getenv ("MONO_RTC"))) {
- int freq = 0;
- inited = 1;
- if (*rtc_freq)
- freq = atoi (rtc_freq);
- if (!freq)
- freq = 1024;
- rtc_fd = open ("/dev/rtc", O_RDONLY);
- if (rtc_fd == -1) {
- perror ("open /dev/rtc");
- return;
- }
- profiling_signal_in_use = SIGPROF;
- add_signal_handler (profiling_signal_in_use, sigprof_signal_handler, SA_RESTART);
- if (ioctl (rtc_fd, RTC_IRQP_SET, freq) == -1) {
- perror ("set rtc freq");
- return;
- }
- if (ioctl (rtc_fd, RTC_PIE_ON, 0) == -1) {
- perror ("start rtc");
- return;
- }
- if (fcntl (rtc_fd, F_SETSIG, SIGPROF) == -1) {
- perror ("setsig");
- return;
- }
- if (fcntl (rtc_fd, F_SETOWN, getpid ()) == -1) {
- perror ("setown");
- return;
+ InterlockedWrite (&sampling_thread_running, 0);
+
+#ifdef HAVE_CLOCK_NANOSLEEP
+ /*
+ * There is a slight problem when we're using CLOCK_PROCESS_CPUTIME_ID: If
+ * we're shutting down and there's largely no activity in the process other
+ * than waiting for the sampler thread to shut down, it can take upwards of
+ * 20 seconds (depending on a lot of factors) for us to shut down because
+ * the sleep progresses very slowly as a result of the low CPU activity.
+ *
+ * We fix this by repeatedly sending the profiler signal to the sampler
+ * thread in order to interrupt the sleep. clock_sleep_ns_abs () will check
+ * sampling_thread_running upon an interrupt and return immediately if it's
+ * zero. profiler_signal_handler () has a special case to ignore the signal
+ * for the sampler thread.
+ *
+ * We do not need to do this on platforms where we use a regular sleep
+ * based on a monotonic clock. The sleep will return in a reasonable amount
+ * of time in those cases.
+ */
+ if (mono_profiler_get_sampling_mode () == MONO_PROFILER_STAT_MODE_PROCESS) {
+ MonoThreadInfo *info;
+
+ // Did it shut down already?
+ if ((info = mono_thread_info_lookup (sampling_thread))) {
+ while (!InterlockedRead (&sampling_thread_exiting)) {
+ mono_threads_pthread_kill (info, profiler_signal);
+ mono_thread_info_usleep (10 * 1000 /* 10ms */);
+ }
+
+ // Make sure info can be freed.
+ mono_hazard_pointer_clear (mono_hazard_pointer_get (), 1);
}
- enable_rtc_timer (TRUE);
- return;
}
- if (rtc_fd >= 0)
- return;
#endif
- itval.it_interval.tv_usec = (1000000 / mono_profiler_get_sampling_rate ()) - 1;
- itval.it_interval.tv_sec = 0;
- itval.it_value = itval.it_interval;
- if (inited)
- return;
- inited = 1;
- profiling_signal_in_use = get_itimer_signal ();
- add_signal_handler (profiling_signal_in_use, sigprof_signal_handler, SA_RESTART);
- setitimer (get_itimer_mode (), &itval, NULL);
+ pthread_join (sampling_thread, NULL);
+
+ /*
+ * We can't safely remove the signal handler because we have no guarantee
+ * that all pending signals have been delivered at this point. This should
+ * not really be a problem anyway.
+ */
+ //remove_signal_handler (profiler_signal);
+}
+
+void
+mono_runtime_setup_stat_profiler (void)
+{
+ /*
+ * Use a real-time signal when possible. This gives us roughly a 99% signal
+ * delivery rate in all cases. On the other hand, using a regular signal
+ * tends to result in awful delivery rates when the application is heavily
+ * loaded.
+ *
+ * We avoid real-time signals on Android as they're super broken in certain
+ * API levels (too small sigset_t, nonsensical SIGRTMIN/SIGRTMAX values,
+ * etc).
+ *
+ * TODO: On Mac, we should explore using the Mach thread suspend/resume
+ * functions and doing the stack walk from the sampling thread. This would
+ * get us a 100% sampling rate. However, this may interfere with the GC's
+ * STW logic. Could perhaps be solved by taking the suspend lock.
+ */
+#if defined (USE_POSIX_BACKEND) && defined (SIGRTMIN) && !defined (PLATFORM_ANDROID)
+ /* Just take the first real-time signal we can get. */
+ profiler_signal = mono_threads_posix_signal_search_alternative (-1);
+#else
+ profiler_signal = SIGPROF;
#endif
+
+ add_signal_handler (profiler_signal, profiler_signal_handler, SA_RESTART);
+
+ mono_counters_register ("Sampling signals sent", MONO_COUNTER_UINT | MONO_COUNTER_PROFILER | MONO_COUNTER_MONOTONIC, &profiler_signals_sent);
+ mono_counters_register ("Sampling signals received", MONO_COUNTER_UINT | MONO_COUNTER_PROFILER | MONO_COUNTER_MONOTONIC, &profiler_signals_received);
+ mono_counters_register ("Sampling signals accepted", MONO_COUNTER_UINT | MONO_COUNTER_PROFILER | MONO_COUNTER_MONOTONIC, &profiler_signals_accepted);
+ mono_counters_register ("Shutdown signals received", MONO_COUNTER_UINT | MONO_COUNTER_PROFILER | MONO_COUNTER_MONOTONIC, &profiler_interrupt_signals_received);
+
+ InterlockedWrite (&sampling_thread_running, 1);
+ mono_native_thread_create (&sampling_thread, sampling_thread_func, NULL);
+}
+
+#else
+
+void
+mono_runtime_shutdown_stat_profiler (void)
+{
}
+void
+mono_runtime_setup_stat_profiler (void)
+{
+}
+
+#endif
+
#if !defined(PLATFORM_MACOSX)
pid_t
mono_runtime_syscall_fork ()
projects / mono.git / blobdiff