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Diffstat (limited to 'gcc-4.8.1/libgo/runtime/cpuprof.c')
| -rw-r--r-- | gcc-4.8.1/libgo/runtime/cpuprof.c | 447 |
1 files changed, 0 insertions, 447 deletions
diff --git a/gcc-4.8.1/libgo/runtime/cpuprof.c b/gcc-4.8.1/libgo/runtime/cpuprof.c deleted file mode 100644 index 3ef08ef51..000000000 --- a/gcc-4.8.1/libgo/runtime/cpuprof.c +++ /dev/null @@ -1,447 +0,0 @@ -// 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 "arch.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 - bool eod_sent; // special end-of-data record sent; => flushing -}; - -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*); - -static uintptr eod[3] = {0, 1, 0}; - -// 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(intgo) - __asm__ (GOSYM_PREFIX "runtime.SetCPUProfileRate"); - -// SetCPUProfileRate sets the CPU profiling rate. -// The user documentation is in debug.go. -void -runtime_SetCPUProfileRate(intgo 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; - prof->eod_sent = 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. - if(!p->eod_sent) { - // We may not have space to append this to the partial log buf, - // so we always return a new slice for the end-of-data marker. - p->eod_sent = true; - ret.array = (byte*)eod; - ret.len = sizeof eod; - ret.cap = ret.len; - return ret; - } - - // 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__ (GOSYM_PREFIX "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); -} |