@@ -423,6 +423,7 @@
runtime/go-unsafe-newarray.c \
runtime/go-unsafe-pointer.c \
runtime/go-unwind.c \
+ runtime/cpuprof.c \
runtime/mcache.c \
runtime/mcentral.c \
$(runtime_mem_file) \
@@ -0,0 +1,432 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// CPU profiling.
+// Based on algorithms and data structures used in
+// http://code.google.com/p/google-perftools/.
+//
+// The main difference between this code and the google-perftools
+// code is that this code is written to allow copying the profile data
+// to an arbitrary io.Writer, while the google-perftools code always
+// writes to an operating system file.
+//
+// The signal handler for the profiling clock tick adds a new stack trace
+// to a hash table tracking counts for recent traces. Most clock ticks
+// hit in the cache. In the event of a cache miss, an entry must be
+// evicted from the hash table, copied to a log that will eventually be
+// written as profile data. The google-perftools code flushed the
+// log itself during the signal handler. This code cannot do that, because
+// the io.Writer might block or need system calls or locks that are not
+// safe to use from within the signal handler. Instead, we split the log
+// into two halves and let the signal handler fill one half while a goroutine
+// is writing out the other half. When the signal handler fills its half, it
+// offers to swap with the goroutine. If the writer is not done with its half,
+// we lose the stack trace for this clock tick (and record that loss).
+// The goroutine interacts with the signal handler by calling getprofile() to
+// get the next log piece to write, implicitly handing back the last log
+// piece it obtained.
+//
+// The state of this dance between the signal handler and the goroutine
+// is encoded in the Profile.handoff field. If handoff == 0, then the goroutine
+// is not using either log half and is waiting (or will soon be waiting) for
+// a new piece by calling notesleep(&p->wait). If the signal handler
+// changes handoff from 0 to non-zero, it must call notewakeup(&p->wait)
+// to wake the goroutine. The value indicates the number of entries in the
+// log half being handed off. The goroutine leaves the non-zero value in
+// place until it has finished processing the log half and then flips the number
+// back to zero. Setting the high bit in handoff means that the profiling is over,
+// and the goroutine is now in charge of flushing the data left in the hash table
+// to the log and returning that data.
+//
+// The handoff field is manipulated using atomic operations.
+// For the most part, the manipulation of handoff is orderly: if handoff == 0
+// then the signal handler owns it and can change it to non-zero.
+// If handoff != 0 then the goroutine owns it and can change it to zero.
+// If that were the end of the story then we would not need to manipulate
+// handoff using atomic operations. The operations are needed, however,
+// in order to let the log closer set the high bit to indicate "EOF" safely
+// in the situation when normally the goroutine "owns" handoff.
+
+#include "runtime.h"
+#include "malloc.h"
+
+#include "array.h"
+typedef struct __go_open_array Slice;
+#define array __values
+#define len __count
+#define cap __capacity
+
+enum
+{
+ HashSize = 1<<10,
+ LogSize = 1<<17,
+ Assoc = 4,
+ MaxStack = 64,
+};
+
+typedef struct Profile Profile;
+typedef struct Bucket Bucket;
+typedef struct Entry Entry;
+
+struct Entry {
+ uintptr count;
+ uintptr depth;
+ uintptr stack[MaxStack];
+};
+
+struct Bucket {
+ Entry entry[Assoc];
+};
+
+struct Profile {
+ bool on; // profiling is on
+ Note wait; // goroutine waits here
+ uintptr count; // tick count
+ uintptr evicts; // eviction count
+ uintptr lost; // lost ticks that need to be logged
+ uintptr totallost; // total lost ticks
+
+ // Active recent stack traces.
+ Bucket hash[HashSize];
+
+ // Log of traces evicted from hash.
+ // Signal handler has filled log[toggle][:nlog].
+ // Goroutine is writing log[1-toggle][:handoff].
+ uintptr log[2][LogSize/2];
+ uintptr nlog;
+ int32 toggle;
+ uint32 handoff;
+
+ // Writer state.
+ // Writer maintains its own toggle to avoid races
+ // looking at signal handler's toggle.
+ uint32 wtoggle;
+ bool wholding; // holding & need to release a log half
+ bool flushing; // flushing hash table - profile is over
+};
+
+static Lock lk;
+static Profile *prof;
+
+static void tick(uintptr*, int32);
+static void add(Profile*, uintptr*, int32);
+static bool evict(Profile*, Entry*);
+static bool flushlog(Profile*);
+
+// LostProfileData is a no-op function used in profiles
+// to mark the number of profiling stack traces that were
+// discarded due to slow data writers.
+static void LostProfileData(void) {
+}
+
+extern void runtime_SetCPUProfileRate(int32)
+ __asm__("libgo_runtime.runtime.SetCPUProfileRate");
+
+// SetCPUProfileRate sets the CPU profiling rate.
+// The user documentation is in debug.go.
+void
+runtime_SetCPUProfileRate(int32 hz)
+{
+ uintptr *p;
+ uintptr n;
+
+ // Clamp hz to something reasonable.
+ if(hz < 0)
+ hz = 0;
+ if(hz > 1000000)
+ hz = 1000000;
+
+ runtime_lock(&lk);
+ if(hz > 0) {
+ if(prof == nil) {
+ prof = runtime_SysAlloc(sizeof *prof);
+ if(prof == nil) {
+ runtime_printf("runtime: cpu profiling cannot allocate memory\n");
+ runtime_unlock(&lk);
+ return;
+ }
+ }
+ if(prof->on || prof->handoff != 0) {
+ runtime_printf("runtime: cannot set cpu profile rate until previous profile has finished.\n");
+ runtime_unlock(&lk);
+ return;
+ }
+
+ prof->on = true;
+ p = prof->log[0];
+ // pprof binary header format.
+ // http://code.google.com/p/google-perftools/source/browse/trunk/src/profiledata.cc#117
+ *p++ = 0; // count for header
+ *p++ = 3; // depth for header
+ *p++ = 0; // version number
+ *p++ = 1000000 / hz; // period (microseconds)
+ *p++ = 0;
+ prof->nlog = p - prof->log[0];
+ prof->toggle = 0;
+ prof->wholding = false;
+ prof->wtoggle = 0;
+ prof->flushing = false;
+ runtime_noteclear(&prof->wait);
+
+ runtime_setcpuprofilerate(tick, hz);
+ } else if(prof->on) {
+ runtime_setcpuprofilerate(nil, 0);
+ prof->on = false;
+
+ // Now add is not running anymore, and getprofile owns the entire log.
+ // Set the high bit in prof->handoff to tell getprofile.
+ for(;;) {
+ n = prof->handoff;
+ if(n&0x80000000)
+ runtime_printf("runtime: setcpuprofile(off) twice");
+ if(runtime_cas(&prof->handoff, n, n|0x80000000))
+ break;
+ }
+ if(n == 0) {
+ // we did the transition from 0 -> nonzero so we wake getprofile
+ runtime_notewakeup(&prof->wait);
+ }
+ }
+ runtime_unlock(&lk);
+}
+
+static void
+tick(uintptr *pc, int32 n)
+{
+ add(prof, pc, n);
+}
+
+// add adds the stack trace to the profile.
+// It is called from signal handlers and other limited environments
+// and cannot allocate memory or acquire locks that might be
+// held at the time of the signal, nor can it use substantial amounts
+// of stack. It is allowed to call evict.
+static void
+add(Profile *p, uintptr *pc, int32 n)
+{
+ int32 i, j;
+ uintptr h, x;
+ Bucket *b;
+ Entry *e;
+
+ if(n > MaxStack)
+ n = MaxStack;
+
+ // Compute hash.
+ h = 0;
+ for(i=0; i<n; i++) {
+ h = h<<8 | (h>>(8*(sizeof(h)-1)));
+ x = pc[i];
+ h += x*31 + x*7 + x*3;
+ }
+ p->count++;
+
+ // Add to entry count if already present in table.
+ b = &p->hash[h%HashSize];
+ for(i=0; i<Assoc; i++) {
+ e = &b->entry[i];
+ if(e->depth != (uintptr)n)
+ continue;
+ for(j=0; j<n; j++)
+ if(e->stack[j] != pc[j])
+ goto ContinueAssoc;
+ e->count++;
+ return;
+ ContinueAssoc:;
+ }
+
+ // Evict entry with smallest count.
+ e = &b->entry[0];
+ for(i=1; i<Assoc; i++)
+ if(b->entry[i].count < e->count)
+ e = &b->entry[i];
+ if(e->count > 0) {
+ if(!evict(p, e)) {
+ // Could not evict entry. Record lost stack.
+ p->lost++;
+ p->totallost++;
+ return;
+ }
+ p->evicts++;
+ }
+
+ // Reuse the newly evicted entry.
+ e->depth = n;
+ e->count = 1;
+ for(i=0; i<n; i++)
+ e->stack[i] = pc[i];
+}
+
+// evict copies the given entry's data into the log, so that
+// the entry can be reused. evict is called from add, which
+// is called from the profiling signal handler, so it must not
+// allocate memory or block. It is safe to call flushLog.
+// evict returns true if the entry was copied to the log,
+// false if there was no room available.
+static bool
+evict(Profile *p, Entry *e)
+{
+ int32 i, d, nslot;
+ uintptr *log, *q;
+
+ d = e->depth;
+ nslot = d+2;
+ log = p->log[p->toggle];
+ if(p->nlog+nslot > nelem(p->log[0])) {
+ if(!flushlog(p))
+ return false;
+ log = p->log[p->toggle];
+ }
+
+ q = log+p->nlog;
+ *q++ = e->count;
+ *q++ = d;
+ for(i=0; i<d; i++)
+ *q++ = e->stack[i];
+ p->nlog = q - log;
+ e->count = 0;
+ return true;
+}
+
+// flushlog tries to flush the current log and switch to the other one.
+// flushlog is called from evict, called from add, called from the signal handler,
+// so it cannot allocate memory or block. It can try to swap logs with
+// the writing goroutine, as explained in the comment at the top of this file.
+static bool
+flushlog(Profile *p)
+{
+ uintptr *log, *q;
+
+ if(!runtime_cas(&p->handoff, 0, p->nlog))
+ return false;
+ runtime_notewakeup(&p->wait);
+
+ p->toggle = 1 - p->toggle;
+ log = p->log[p->toggle];
+ q = log;
+ if(p->lost > 0) {
+ *q++ = p->lost;
+ *q++ = 1;
+ *q++ = (uintptr)LostProfileData;
+ }
+ p->nlog = q - log;
+ return true;
+}
+
+// getprofile blocks until the next block of profiling data is available
+// and returns it as a []byte. It is called from the writing goroutine.
+Slice
+getprofile(Profile *p)
+{
+ uint32 i, j, n;
+ Slice ret;
+ Bucket *b;
+ Entry *e;
+
+ ret.array = nil;
+ ret.len = 0;
+ ret.cap = 0;
+
+ if(p == nil)
+ return ret;
+
+ if(p->wholding) {
+ // Release previous log to signal handling side.
+ // Loop because we are racing against setprofile(off).
+ for(;;) {
+ n = p->handoff;
+ if(n == 0) {
+ runtime_printf("runtime: phase error during cpu profile handoff\n");
+ return ret;
+ }
+ if(n & 0x80000000) {
+ p->wtoggle = 1 - p->wtoggle;
+ p->wholding = false;
+ p->flushing = true;
+ goto flush;
+ }
+ if(runtime_cas(&p->handoff, n, 0))
+ break;
+ }
+ p->wtoggle = 1 - p->wtoggle;
+ p->wholding = false;
+ }
+
+ if(p->flushing)
+ goto flush;
+
+ if(!p->on && p->handoff == 0)
+ return ret;
+
+ // Wait for new log.
+ // runtime·entersyscall();
+ runtime_notesleep(&p->wait);
+ // runtime·exitsyscall();
+ runtime_noteclear(&p->wait);
+
+ n = p->handoff;
+ if(n == 0) {
+ runtime_printf("runtime: phase error during cpu profile wait\n");
+ return ret;
+ }
+ if(n == 0x80000000) {
+ p->flushing = true;
+ goto flush;
+ }
+ n &= ~0x80000000;
+
+ // Return new log to caller.
+ p->wholding = true;
+
+ ret.array = (byte*)p->log[p->wtoggle];
+ ret.len = n*sizeof(uintptr);
+ ret.cap = ret.len;
+ return ret;
+
+flush:
+ // In flush mode.
+ // Add is no longer being called. We own the log.
+ // Also, p->handoff is non-zero, so flushlog will return false.
+ // Evict the hash table into the log and return it.
+ for(i=0; i<HashSize; i++) {
+ b = &p->hash[i];
+ for(j=0; j<Assoc; j++) {
+ e = &b->entry[j];
+ if(e->count > 0 && !evict(p, e)) {
+ // Filled the log. Stop the loop and return what we've got.
+ goto breakflush;
+ }
+ }
+ }
+breakflush:
+
+ // Return pending log data.
+ if(p->nlog > 0) {
+ // Note that we're using toggle now, not wtoggle,
+ // because we're working on the log directly.
+ ret.array = (byte*)p->log[p->toggle];
+ ret.len = p->nlog*sizeof(uintptr);
+ ret.cap = ret.len;
+ p->nlog = 0;
+ return ret;
+ }
+
+ // Made it through the table without finding anything to log.
+ // Finally done. Clean up and return nil.
+ p->flushing = false;
+ if(!runtime_cas(&p->handoff, p->handoff, 0))
+ runtime_printf("runtime: profile flush racing with something\n");
+ return ret; // set to nil at top of function
+}
+
+extern Slice runtime_CPUProfile(void)
+ __asm__("libgo_runtime.runtime.CPUProfile");
+
+// CPUProfile returns the next cpu profile block as a []byte.
+// The user documentation is in debug.go.
+Slice
+runtime_CPUProfile(void)
+{
+ return getprofile(prof);
+}
@@ -21,7 +21,7 @@
notewakeup. */
void
-noteclear (Note* n)
+runtime_noteclear (Note* n)
{
int32 i;
@@ -37,7 +37,7 @@
/* Wait until notewakeup is called. */
void
-notesleep (Note* n)
+runtime_notesleep (Note* n)
{
int32 i;
@@ -57,7 +57,7 @@
/* Wake up every thread sleeping on the note. */
void
-notewakeup (Note *n)
+runtime_notewakeup (Note *n)
{
int32 i;
@@ -6,6 +6,7 @@
#include <signal.h>
#include <stdlib.h>
+#include <sys/time.h>
#include "go-assert.h"
#include "go-panic.h"
@@ -13,10 +14,8 @@
#include "runtime.h"
-#undef int
-
-#ifndef SA_ONSTACK
-#define SA_ONSTACK 0
+#ifndef SA_RESTART
+ #define SA_RESTART 0
#endif
/* What to do for a signal. */
@@ -27,68 +26,70 @@
int sig;
/* Nonzero if the signal should be ignored. */
_Bool ignore;
+ /* Nonzero if we should restart system calls. */
+ _Bool restart;
};
/* What to do for signals. */
static struct sigtab signals[] =
{
- { SIGHUP, 0 },
- { SIGINT, 0 },
- { SIGALRM, 1 },
- { SIGTERM, 0 },
+ { SIGHUP, 0, 1 },
+ { SIGINT, 0, 1 },
+ { SIGALRM, 1, 1 },
+ { SIGTERM, 0, 1 },
#ifdef SIGBUS
- { SIGBUS, 0 },
+ { SIGBUS, 0, 0 },
#endif
#ifdef SIGFPE
- { SIGFPE, 0 },
+ { SIGFPE, 0, 0 },
#endif
#ifdef SIGUSR1
- { SIGUSR1, 1 },
+ { SIGUSR1, 1, 1 },
#endif
#ifdef SIGSEGV
- { SIGSEGV, 0 },
+ { SIGSEGV, 0, 0 },
#endif
#ifdef SIGUSR2
- { SIGUSR2, 1 },
+ { SIGUSR2, 1, 1 },
#endif
#ifdef SIGPIPE
- { SIGPIPE, 1 },
+ { SIGPIPE, 1, 0 },
#endif
#ifdef SIGCHLD
- { SIGCHLD, 1 },
+ { SIGCHLD, 1, 1 },
#endif
#ifdef SIGTSTP
- { SIGTSTP, 1 },
+ { SIGTSTP, 1, 1 },
#endif
#ifdef SIGTTIN
- { SIGTTIN, 1 },
+ { SIGTTIN, 1, 1 },
#endif
#ifdef SIGTTOU
- { SIGTTOU, 1 },
+ { SIGTTOU, 1, 1 },
#endif
#ifdef SIGURG
- { SIGURG, 1 },
+ { SIGURG, 1, 1 },
#endif
#ifdef SIGXCPU
- { SIGXCPU, 1 },
+ { SIGXCPU, 1, 1 },
#endif
#ifdef SIGXFSZ
- { SIGXFSZ, 1 },
+ { SIGXFSZ, 1, 1 },
#endif
#ifdef SIGVTARLM
- { SIGVTALRM, 1 },
+ { SIGVTALRM, 1, 1 },
#endif
#ifdef SIGWINCH
- { SIGWINCH, 1 },
+ { SIGWINCH, 1, 1 },
#endif
#ifdef SIGIO
- { SIGIO, 1 },
+ { SIGIO, 1, 1 },
#endif
#ifdef SIGPWR
- { SIGPWR, 1 },
+ { SIGPWR, 1, 1 },
#endif
- { -1, 0 }
+ { -1, 0, 0 }
};
/* The Go signal handler. */
@@ -99,6 +100,13 @@
const char *msg;
int i;
+ if (sig == SIGPROF)
+ {
+ /* FIXME. */
+ runtime_sigprof (0, 0, nil);
+ return;
+ }
+
/* FIXME: Should check siginfo for more information when
available. */
msg = NULL;
@@ -192,6 +200,48 @@
__go_assert (i == 0);
for (i = 0; signals[i].sig != -1; ++i)
- if (sigaction (signals[i].sig, &sa, NULL) != 0)
- __go_assert (0);
+ {
+ sa.sa_flags = signals[i].restart ? SA_RESTART : 0;
+ if (sigaction (signals[i].sig, &sa, NULL) != 0)
+ __go_assert (0);
+ }
}
+
+void
+runtime_resetcpuprofiler(int32 hz)
+{
+ struct itimerval it;
+ struct sigaction sa;
+ int i;
+
+ memset (&it, 0, sizeof it);
+
+ memset (&sa, 0, sizeof sa);
+ i = sigfillset (&sa.sa_mask);
+ __go_assert (i == 0);
+
+ if (hz == 0)
+ {
+ i = setitimer (ITIMER_PROF, &it, NULL);
+ __go_assert (i == 0);
+
+ sa.sa_handler = SIG_IGN;
+ i = sigaction (SIGPROF, &sa, NULL);
+ __go_assert (i == 0);
+ }
+ else
+ {
+ sa.sa_handler = sighandler;
+ sa.sa_flags = SA_RESTART;
+ i = sigaction (SIGPROF, &sa, NULL);
+ __go_assert (i == 0);
+
+ it.it_interval.tv_sec = 0;
+ it.it_interval.tv_usec = 1000000 / hz;
+ it.it_value = it.it_interval;
+ i = setitimer (ITIMER_PROF, &it, NULL);
+ __go_assert (i == 0);
+ }
+
+ m->profilehz = hz;
+}
@@ -14,3 +14,60 @@
#endif
__thread M *m = &m0;
+
+static struct {
+ Lock;
+ void (*fn)(uintptr*, int32);
+ int32 hz;
+ uintptr pcbuf[100];
+} prof;
+
+void
+runtime_sigprof(uint8 *pc __attribute__ ((unused)),
+ uint8 *sp __attribute__ ((unused)),
+ uint8 *lr __attribute__ ((unused)))
+{
+ int32 n;
+
+ if(prof.fn == nil || prof.hz == 0)
+ return;
+
+ runtime_lock(&prof);
+ if(prof.fn == nil) {
+ runtime_unlock(&prof);
+ return;
+ }
+ n = 0;
+ // n = runtime·gentraceback(pc, sp, lr, gp, 0, prof.pcbuf, nelem(prof.pcbuf));
+ if(n > 0)
+ prof.fn(prof.pcbuf, n);
+ runtime_unlock(&prof);
+}
+
+void
+runtime_setcpuprofilerate(void (*fn)(uintptr*, int32), int32 hz)
+{
+ // Force sane arguments.
+ if(hz < 0)
+ hz = 0;
+ if(hz == 0)
+ fn = nil;
+ if(fn == nil)
+ hz = 0;
+
+ // Stop profiler on this cpu so that it is safe to lock prof.
+ // if a profiling signal came in while we had prof locked,
+ // it would deadlock.
+ runtime_resetcpuprofiler(0);
+
+ runtime_lock(&prof);
+ prof.fn = fn;
+ prof.hz = hz;
+ runtime_unlock(&prof);
+ // runtime_lock(&runtime_sched);
+ // runtime_sched.profilehz = hz;
+ // runtime_unlock(&runtime_sched);
+
+ if(hz != 0)
+ runtime_resetcpuprofiler(hz);
+}
@@ -102,6 +102,7 @@
int32 gcing_for_prof;
int32 holds_finlock;
int32 gcing_for_finlock;
+ int32 profilehz;
MCache *mcache;
/* For the list of all threads. */
@@ -163,9 +164,9 @@
* once notewakeup has been called, all the notesleeps
* will return. future notesleeps will return immediately.
*/
-void noteclear(Note*);
-void notesleep(Note*);
-void notewakeup(Note*);
+void runtime_noteclear(Note*);
+void runtime_notesleep(Note*);
+void runtime_notewakeup(Note*);
/* Functions. */
#define runtime_printf printf
@@ -187,6 +188,10 @@
#define runtime_cas(pval, old, new) __sync_bool_compare_and_swap (pval, old, new)
#define runtime_casp(pval, old, new) __sync_bool_compare_and_swap (pval, old, new)
+void runtime_sigprof(uint8 *pc, uint8 *sp, uint8 *lr);
+void runtime_resetcpuprofiler(int32);
+void runtime_setcpuprofilerate(void(*)(uintptr*, int32), int32);
+
struct __go_func_type;
void reflect_call(const struct __go_func_type *, const void *, _Bool, void **,
void **)
@@ -51,7 +51,7 @@
void
siginit(void)
{
- noteclear(&sig);
+ runtime_noteclear(&sig);
}
// Called from sighandler to send a signal back out of the signal handling thread.
@@ -71,7 +71,7 @@
// Added to queue.
// Only send a wakeup for the first signal in each round.
if(mask == 0)
- notewakeup(&sig);
+ runtime_notewakeup(&sig);
break;
}
}
@@ -81,9 +81,9 @@
// Called to receive a bitmask of queued signals.
func Sigrecv() (m uint32) {
// runtime·entersyscall();
- notesleep(&sig);
+ runtime_notesleep(&sig);
// runtime·exitsyscall();
- noteclear(&sig);
+ runtime_noteclear(&sig);
for(;;) {
m = sig.mask;
if(runtime_cas(&sig.mask, m, 0))