2012-09-30 Paul Eggert <eggert@cs.ucla.edu>
+ Profiler improvements: more-accurate timers, overflow checks.
+ * profiler.c: Don't include stdio.h, limits.h, sys/time.h,
+ signal.h, setjmp.h. Include systime.h instead.
+ (saturated_add): New function.
+ (record_backtrace, current_sample_interval): Use EMACS_INT, not size_t.
+ (record_backtrace, handle_profiler_signal): Saturate on fixnum overflow.
+ (profiler_timer, profiler_timer_ok) [HAVE_TIMER_SETTIME]:
+ New static vars.
+ (enum profiler_cpu_running): New enumn.
+ (profiler_cpu_running): Now of that enum type, not bool.
+ All uses changed to store the new value.
+ (handle_profiler_signal): Rename from sigprof_handler_1,
+ for consistency with other handlers. Do not check whether
+ cpu_log is a hash-table if garbage collecting, since it
+ doesn't matter in that case.
+ (deliver_profiler_signal): Rename from sigprof_handler,
+ for consistency with other handlers.
+ (setup_cpu_timer): New function, with much of what used to be in
+ Fprofiler_cpu_start. Check for out-of-range argument.
+ Prefer timer_settime if available, and prefer
+ thread cputime clocks, then process cputime clocks, then
+ monotonic clocks, to the old realtime clock. Use make_timeval
+ to round more-correctly when falling back to setitimer.
+ (Fprofiler_cpu_start): Use it.
+ (Fprofiler_cpu_stop): Prefer timer_settime if available.
+ Don't assume that passing NULL as the 2nd argument of setitimer
+ is the same as passing a pointer to all-zero storage.
+ Ignore SIGPROF afterwards.
+ (malloc_probe): Saturate at MOST_POSITIVE_FIXNUM.
+ * sysdep.c (emacs_sigaction_init): Also mask out SIGPROF in
+ non-fatal signal handlers. Ignore SIGPROF on startup.
+ * syssignal.h (PROFILER_CPU_SUPPORT): Define this macro here, not
+ in profiler.c, since sysdep.c now uses it.
+
* sysdep.c (handle_fatal_signal): Bump backtrace size to 40.
Suggested by Eli Zaretskii in
<http://lists.gnu.org/archive/html/emacs-devel/2012-09/msg00796.html>.
along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
#include <config.h>
-#include <stdio.h>
-#include <limits.h>
-#include <sys/time.h>
-#include <signal.h>
-#include <setjmp.h>
#include "lisp.h"
#include "syssignal.h"
+#include "systime.h"
+
+/* Return A + B, but return the maximum fixnum if the result would overflow.
+ Assume A and B are nonnegative and in fixnum range. */
+
+static EMACS_INT
+saturated_add (EMACS_INT a, EMACS_INT b)
+{
+ return min (a + b, MOST_POSITIVE_FIXNUM);
+}
/* Logs. */
}
}
-/* Record the current backtrace in LOG. BASE is a special name for
- describing which the backtrace come from. BASE can be nil. COUNT is
- a number how many times the profiler sees the backtrace at the
- time. ELAPSED is a elapsed time in millisecond that the backtrace
- took. */
+/* Record the current backtrace in LOG. COUNT is the weight of this
+ current backtrace: milliseconds for CPU counts, and the allocation
+ size for memory logs. */
static void
-record_backtrace (log_t *log, size_t count)
+record_backtrace (log_t *log, EMACS_INT count)
{
struct backtrace *backlist = backtrace_list;
Lisp_Object backtrace;
EMACS_UINT hash;
ptrdiff_t j = hash_lookup (log, backtrace, &hash);
if (j >= 0)
- set_hash_value_slot (log, j,
- make_number (count + XINT (HASH_VALUE (log, j))));
+ {
+ EMACS_INT old_val = XINT (HASH_VALUE (log, j));
+ EMACS_INT new_val = saturated_add (old_val, count);
+ set_hash_value_slot (log, j, make_number (new_val));
+ }
else
{ /* BEWARE! hash_put in general can allocate memory.
But currently it only does that if log->next_free is nil. */
/* Sample profiler. */
/* FIXME: Add support for the CPU profiler in W32. */
-/* FIXME: the sigprof_handler suffers from race-conditions if the signal
- is delivered to a thread other than the main Emacs thread. */
-#if defined SIGPROF && defined HAVE_SETITIMER
-#define PROFILER_CPU_SUPPORT
+#ifdef PROFILER_CPU_SUPPORT
+
+/* The profiler timer and whether it was properly initialized, if
+ POSIX timers are available. */
+#ifdef HAVE_TIMER_SETTIME
+static timer_t profiler_timer;
+static bool profiler_timer_ok;
+#endif
-/* True if sampling profiler is running. */
-static bool profiler_cpu_running;
+/* Status of sampling profiler. */
+static enum profiler_cpu_running
+ { NOT_RUNNING, TIMER_SETTIME_RUNNING, SETITIMER_RUNNING }
+ profiler_cpu_running;
+/* Hash-table log of CPU profiler. */
static Lisp_Object cpu_log;
+
/* Separate counter for the time spent in the GC. */
static EMACS_INT cpu_gc_count;
-/* The current sample interval in millisecond. */
-
-static int current_sample_interval;
+/* The current sample interval in milliseconds. */
+static EMACS_INT current_sample_interval;
/* Signal handler for sample profiler. */
static void
-sigprof_handler_1 (int signal)
+handle_profiler_signal (int signal)
{
- eassert (HASH_TABLE_P (cpu_log));
if (backtrace_list && EQ (backtrace_list->function, Qautomatic_gc))
/* Special case the time-count inside GC because the hash-table
code is not prepared to be used while the GC is running.
not expect the ARRAY_MARK_FLAG to be set. We could try and
harden the hash-table code, but it doesn't seem worth the
effort. */
- cpu_gc_count += current_sample_interval;
+ cpu_gc_count = saturated_add (cpu_gc_count, current_sample_interval);
else
- record_backtrace (XHASH_TABLE (cpu_log), current_sample_interval);
+ {
+ eassert (HASH_TABLE_P (cpu_log));
+ record_backtrace (XHASH_TABLE (cpu_log), current_sample_interval);
+ }
}
static void
-sigprof_handler (int signal)
+deliver_profiler_signal (int signal)
+{
+ deliver_process_signal (signal, handle_profiler_signal);
+}
+
+static enum profiler_cpu_running
+setup_cpu_timer (Lisp_Object sample_interval)
{
- deliver_process_signal (signal, sigprof_handler_1);
+ struct sigaction action;
+ struct itimerval timer;
+ struct timespec interval;
+
+ if (! RANGED_INTEGERP (1, sample_interval,
+ (TYPE_MAXIMUM (time_t) < EMACS_INT_MAX / 1000
+ ? (EMACS_INT) TYPE_MAXIMUM (time_t) * 1000 + 999
+ : EMACS_INT_MAX)))
+ return NOT_RUNNING;
+
+ current_sample_interval = XINT (sample_interval);
+ interval = make_emacs_time (current_sample_interval / 1000,
+ current_sample_interval % 1000 * 1000000);
+ emacs_sigaction_init (&action, deliver_profiler_signal);
+ sigaction (SIGPROF, &action, 0);
+
+#ifdef HAVE_TIMER_SETTIME
+ if (! profiler_timer_ok)
+ {
+ /* System clocks to try, in decreasing order of desirability. */
+ static clockid_t const system_clock[] = {
+#ifdef CLOCK_THREAD_CPUTIME_ID
+ CLOCK_THREAD_CPUTIME_ID,
+#endif
+#ifdef CLOCK_PROCESS_CPUTIME_ID
+ CLOCK_PROCESS_CPUTIME_ID,
+#endif
+#ifdef CLOCK_MONOTONIC
+ CLOCK_MONOTONIC,
+#endif
+ CLOCK_REALTIME
+ };
+ int i;
+ struct sigevent sigev;
+ sigev.sigev_value.sival_ptr = &profiler_timer;
+ sigev.sigev_signo = SIGPROF;
+ sigev.sigev_notify = SIGEV_SIGNAL;
+
+ for (i = 0; i < sizeof system_clock / sizeof *system_clock; i++)
+ if (timer_create (system_clock[i], &sigev, &profiler_timer) == 0)
+ {
+ profiler_timer_ok = 1;
+ break;
+ }
+ }
+
+ if (profiler_timer_ok)
+ {
+ struct itimerspec ispec;
+ ispec.it_value = ispec.it_interval = interval;
+ timer_settime (profiler_timer, 0, &ispec, 0);
+ return TIMER_SETTIME_RUNNING;
+ }
+#endif
+
+ timer.it_value = timer.it_interval = make_timeval (interval);
+ setitimer (ITIMER_PROF, &timer, 0);
+ return SETITIMER_RUNNING;
}
DEFUN ("profiler-cpu-start", Fprofiler_cpu_start, Sprofiler_cpu_start,
1, 1, 0,
doc: /* Start or restart the cpu profiler.
-The cpu profiler will take call-stack samples each SAMPLE-INTERVAL (expressed in milliseconds).
+It takes call-stack samples each SAMPLE-INTERVAL milliseconds.
See also `profiler-log-size' and `profiler-max-stack-depth'. */)
(Lisp_Object sample_interval)
{
- struct sigaction sa;
- struct itimerval timer;
-
if (profiler_cpu_running)
error ("Sample profiler is already running");
profiler_max_stack_depth);
}
- current_sample_interval = XINT (sample_interval);
-
- sa.sa_handler = sigprof_handler;
- sa.sa_flags = SA_RESTART;
- sigemptyset (&sa.sa_mask);
- sigaction (SIGPROF, &sa, 0);
-
- timer.it_interval.tv_sec = 0;
- timer.it_interval.tv_usec = current_sample_interval * 1000;
- timer.it_value = timer.it_interval;
- setitimer (ITIMER_PROF, &timer, 0);
-
- profiler_cpu_running = true;
+ profiler_cpu_running = setup_cpu_timer (sample_interval);
+ if (! profiler_cpu_running)
+ error ("Invalid sample interval");
return Qt;
}
Return non-nil if the profiler was running. */)
(void)
{
- if (!profiler_cpu_running)
- return Qnil;
- profiler_cpu_running = false;
+ switch (profiler_cpu_running)
+ {
+ case NOT_RUNNING:
+ return Qnil;
+
+ case TIMER_SETTIME_RUNNING:
+ {
+ struct itimerspec disable;
+ memset (&disable, 0, sizeof disable);
+ timer_settime (profiler_timer, 0, &disable, 0);
+ }
+ break;
- setitimer (ITIMER_PROF, 0, 0);
+ case SETITIMER_RUNNING:
+ {
+ struct itimerval disable;
+ memset (&disable, 0, sizeof disable);
+ setitimer (ITIMER_PROF, &disable, 0);
+ }
+ break;
+ }
+ signal (SIGPROF, SIG_IGN);
+ profiler_cpu_running = NOT_RUNNING;
return Qt;
}
(void)
{
Lisp_Object result = cpu_log;
- /* Here we're making the log visible to Elisp , so it's not safe any
+ /* Here we're making the log visible to Elisp, so it's not safe any
more for our use afterwards since we can't rely on its special
pre-allocated keys anymore. So we have to allocate a new one. */
cpu_log = (profiler_cpu_running
cpu_gc_count = 0;
return result;
}
-#endif /* not defined PROFILER_CPU_SUPPORT */
+#endif /* PROFILER_CPU_SUPPORT */
\f
/* Memory profiler. */
malloc_probe (size_t size)
{
eassert (HASH_TABLE_P (memory_log));
- record_backtrace (XHASH_TABLE (memory_log), size);
+ record_backtrace (XHASH_TABLE (memory_log), min (size, MOST_POSITIVE_FIXNUM));
}
void
profiler_log_size = 10000;
#ifdef PROFILER_CPU_SUPPORT
- profiler_cpu_running = false;
+ profiler_cpu_running = NOT_RUNNING;
cpu_log = Qnil;
staticpro (&cpu_log);
defsubr (&Sprofiler_cpu_start);
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