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// Copyright 2009 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.
// Malloc profiling.
// Patterned after tcmalloc's algorithms; shorter code.
package runtime
#include "runtime.h"
#include "arch_GOARCH.h"
#include "malloc.h"
#include "defs_GOOS_GOARCH.h"
#include "type.h"
// NOTE(rsc): Everything here could use cas if contention became an issue.
static Lock proflock;
// All memory allocations are local and do not escape outside of the profiler.
// The profiler is forbidden from referring to garbage-collected memory.
enum { MProf, BProf }; // profile types
// Per-call-stack profiling information.
// Lookup by hashing call stack into a linked-list hash table.
struct Bucket
{
Bucket *next; // next in hash list
Bucket *allnext; // next in list of all mbuckets/bbuckets
int32 typ;
// Generally unions can break precise GC,
// this one is fine because it does not contain pointers.
union
{
struct // typ == MProf
{
// The following complex 3-stage scheme of stats accumulation
// is required to obtain a consistent picture of mallocs and frees
// for some point in time.
// The problem is that mallocs come in real time, while frees
// come only after a GC during concurrent sweeping. So if we would
// naively count them, we would get a skew toward mallocs.
//
// Mallocs are accounted in recent stats.
// Explicit frees are accounted in recent stats.
// GC frees are accounted in prev stats.
// After GC prev stats are added to final stats and
// recent stats are moved into prev stats.
uintptr allocs;
uintptr frees;
uintptr alloc_bytes;
uintptr free_bytes;
uintptr prev_allocs; // since last but one till last gc
uintptr prev_frees;
uintptr prev_alloc_bytes;
uintptr prev_free_bytes;
uintptr recent_allocs; // since last gc till now
uintptr recent_frees;
uintptr recent_alloc_bytes;
uintptr recent_free_bytes;
};
struct // typ == BProf
{
int64 count;
int64 cycles;
};
};
uintptr hash; // hash of size + stk
uintptr size;
uintptr nstk;
uintptr stk[1];
};
enum {
BuckHashSize = 179999,
};
static Bucket **buckhash;
static Bucket *mbuckets; // memory profile buckets
static Bucket *bbuckets; // blocking profile buckets
static uintptr bucketmem;
// Return the bucket for stk[0:nstk], allocating new bucket if needed.
static Bucket*
stkbucket(int32 typ, uintptr size, uintptr *stk, int32 nstk, bool alloc)
{
int32 i;
uintptr h;
Bucket *b;
if(buckhash == nil) {
buckhash = runtime·SysAlloc(BuckHashSize*sizeof buckhash[0], &mstats.buckhash_sys);
if(buckhash == nil)
runtime·throw("runtime: cannot allocate memory");
}
// Hash stack.
h = 0;
for(i=0; i<nstk; i++) {
h += stk[i];
h += h<<10;
h ^= h>>6;
}
// hash in size
h += size;
h += h<<10;
h ^= h>>6;
// finalize
h += h<<3;
h ^= h>>11;
i = h%BuckHashSize;
for(b = buckhash[i]; b; b=b->next)
if(b->typ == typ && b->hash == h && b->size == size && b->nstk == nstk &&
runtime·mcmp((byte*)b->stk, (byte*)stk, nstk*sizeof stk[0]) == 0)
return b;
if(!alloc)
return nil;
b = runtime·persistentalloc(sizeof *b + nstk*sizeof stk[0], 0, &mstats.buckhash_sys);
bucketmem += sizeof *b + nstk*sizeof stk[0];
runtime·memmove(b->stk, stk, nstk*sizeof stk[0]);
b->typ = typ;
b->hash = h;
b->size = size;
b->nstk = nstk;
b->next = buckhash[i];
buckhash[i] = b;
if(typ == MProf) {
b->allnext = mbuckets;
mbuckets = b;
} else {
b->allnext = bbuckets;
bbuckets = b;
}
return b;
}
static void
MProf_GC(void)
{
Bucket *b;
for(b=mbuckets; b; b=b->allnext) {
b->allocs += b->prev_allocs;
b->frees += b->prev_frees;
b->alloc_bytes += b->prev_alloc_bytes;
b->free_bytes += b->prev_free_bytes;
b->prev_allocs = b->recent_allocs;
b->prev_frees = b->recent_frees;
b->prev_alloc_bytes = b->recent_alloc_bytes;
b->prev_free_bytes = b->recent_free_bytes;
b->recent_allocs = 0;
b->recent_frees = 0;
b->recent_alloc_bytes = 0;
b->recent_free_bytes = 0;
}
}
// Record that a gc just happened: all the 'recent' statistics are now real.
void
runtime·MProf_GC(void)
{
runtime·lock(&proflock);
MProf_GC();
runtime·unlock(&proflock);
}
// Called by malloc to record a profiled block.
void
runtime·MProf_Malloc(void *p, uintptr size)
{
uintptr stk[32];
Bucket *b;
int32 nstk;
nstk = runtime·callers(1, stk, nelem(stk));
runtime·lock(&proflock);
b = stkbucket(MProf, size, stk, nstk, true);
b->recent_allocs++;
b->recent_alloc_bytes += size;
runtime·unlock(&proflock);
// Setprofilebucket locks a bunch of other mutexes, so we call it outside of proflock.
// This reduces potential contention and chances of deadlocks.
// Since the object must be alive during call to MProf_Malloc,
// it's fine to do this non-atomically.
runtime·setprofilebucket(p, b);
}
// Called when freeing a profiled block.
void
runtime·MProf_Free(Bucket *b, uintptr size, bool freed)
{
runtime·lock(&proflock);
if(freed) {
b->recent_frees++;
b->recent_free_bytes += size;
} else {
b->prev_frees++;
b->prev_free_bytes += size;
}
runtime·unlock(&proflock);
}
int64 runtime·blockprofilerate; // in CPU ticks
void
runtime·SetBlockProfileRate(intgo rate)
{
int64 r;
if(rate <= 0)
r = 0; // disable profiling
else {
// convert ns to cycles, use float64 to prevent overflow during multiplication
r = (float64)rate*runtime·tickspersecond()/(1000*1000*1000);
if(r == 0)
r = 1;
}
runtime·atomicstore64((uint64*)&runtime·blockprofilerate, r);
}
void
runtime·blockevent(int64 cycles, int32 skip)
{
int32 nstk;
int64 rate;
uintptr stk[32];
Bucket *b;
if(cycles <= 0)
return;
rate = runtime·atomicload64((uint64*)&runtime·blockprofilerate);
if(rate <= 0 || (rate > cycles && runtime·fastrand1()%rate > cycles))
return;
nstk = runtime·callers(skip, stk, nelem(stk));
runtime·lock(&proflock);
b = stkbucket(BProf, 0, stk, nstk, true);
b->count++;
b->cycles += cycles;
runtime·unlock(&proflock);
}
// Go interface to profile data. (Declared in debug.go)
// Must match MemProfileRecord in debug.go.
typedef struct Record Record;
struct Record {
int64 alloc_bytes, free_bytes;
int64 alloc_objects, free_objects;
uintptr stk[32];
};
// Write b's data to r.
static void
record(Record *r, Bucket *b)
{
int32 i;
r->alloc_bytes = b->alloc_bytes;
r->free_bytes = b->free_bytes;
r->alloc_objects = b->allocs;
r->free_objects = b->frees;
for(i=0; i<b->nstk && i<nelem(r->stk); i++)
r->stk[i] = b->stk[i];
for(; i<nelem(r->stk); i++)
r->stk[i] = 0;
}
func MemProfile(p Slice, include_inuse_zero bool) (n int, ok bool) {
Bucket *b;
Record *r;
bool clear;
runtime·lock(&proflock);
n = 0;
clear = true;
for(b=mbuckets; b; b=b->allnext) {
if(include_inuse_zero || b->alloc_bytes != b->free_bytes)
n++;
if(b->allocs != 0 || b->frees != 0)
clear = false;
}
if(clear) {
// Absolutely no data, suggesting that a garbage collection
// has not yet happened. In order to allow profiling when
// garbage collection is disabled from the beginning of execution,
// accumulate stats as if a GC just happened, and recount buckets.
MProf_GC();
MProf_GC();
n = 0;
for(b=mbuckets; b; b=b->allnext)
if(include_inuse_zero || b->alloc_bytes != b->free_bytes)
n++;
}
ok = false;
if(n <= p.len) {
ok = true;
r = (Record*)p.array;
for(b=mbuckets; b; b=b->allnext)
if(include_inuse_zero || b->alloc_bytes != b->free_bytes)
record(r++, b);
}
runtime·unlock(&proflock);
}
void
runtime·iterate_memprof(void (*callback)(Bucket*, uintptr, uintptr*, uintptr, uintptr, uintptr))
{
Bucket *b;
runtime·lock(&proflock);
for(b=mbuckets; b; b=b->allnext) {
callback(b, b->nstk, b->stk, b->size, b->allocs, b->frees);
}
runtime·unlock(&proflock);
}
// Must match BlockProfileRecord in debug.go.
typedef struct BRecord BRecord;
struct BRecord {
int64 count;
int64 cycles;
uintptr stk[32];
};
func BlockProfile(p Slice) (n int, ok bool) {
Bucket *b;
BRecord *r;
int32 i;
runtime·lock(&proflock);
n = 0;
for(b=bbuckets; b; b=b->allnext)
n++;
ok = false;
if(n <= p.len) {
ok = true;
r = (BRecord*)p.array;
for(b=bbuckets; b; b=b->allnext, r++) {
r->count = b->count;
r->cycles = b->cycles;
for(i=0; i<b->nstk && i<nelem(r->stk); i++)
r->stk[i] = b->stk[i];
for(; i<nelem(r->stk); i++)
r->stk[i] = 0;
}
}
runtime·unlock(&proflock);
}
// Must match StackRecord in debug.go.
typedef struct TRecord TRecord;
struct TRecord {
uintptr stk[32];
};
func ThreadCreateProfile(p Slice) (n int, ok bool) {
TRecord *r;
M *first, *mp;
first = runtime·atomicloadp(&runtime·allm);
n = 0;
for(mp=first; mp; mp=mp->alllink)
n++;
ok = false;
if(n <= p.len) {
ok = true;
r = (TRecord*)p.array;
for(mp=first; mp; mp=mp->alllink) {
runtime·memmove(r->stk, mp->createstack, sizeof r->stk);
r++;
}
}
}
func Stack(b Slice, all bool) (n int) {
uintptr pc, sp;
sp = runtime·getcallersp(&b);
pc = (uintptr)runtime·getcallerpc(&b);
if(all) {
runtime·semacquire(&runtime·worldsema, false);
m->gcing = 1;
runtime·stoptheworld();
}
if(b.len == 0)
n = 0;
else{
g->writebuf = (byte*)b.array;
g->writenbuf = b.len;
runtime·goroutineheader(g);
runtime·traceback(pc, sp, 0, g);
if(all)
runtime·tracebackothers(g);
n = b.len - g->writenbuf;
g->writebuf = nil;
g->writenbuf = 0;
}
if(all) {
m->gcing = 0;
runtime·semrelease(&runtime·worldsema);
runtime·starttheworld();
}
}
static void
saveg(uintptr pc, uintptr sp, G *gp, TRecord *r)
{
int32 n;
n = runtime·gentraceback(pc, sp, 0, gp, 0, r->stk, nelem(r->stk), nil, nil, false);
if(n < nelem(r->stk))
r->stk[n] = 0;
}
func GoroutineProfile(b Slice) (n int, ok bool) {
uintptr pc, sp, i;
TRecord *r;
G *gp;
sp = runtime·getcallersp(&b);
pc = (uintptr)runtime·getcallerpc(&b);
ok = false;
n = runtime·gcount();
if(n <= b.len) {
runtime·semacquire(&runtime·worldsema, false);
m->gcing = 1;
runtime·stoptheworld();
n = runtime·gcount();
if(n <= b.len) {
ok = true;
r = (TRecord*)b.array;
saveg(pc, sp, g, r++);
for(i = 0; i < runtime·allglen; i++) {
gp = runtime·allg[i];
if(gp == g || gp->status == Gdead)
continue;
saveg(~(uintptr)0, ~(uintptr)0, gp, r++);
}
}
m->gcing = 0;
runtime·semrelease(&runtime·worldsema);
runtime·starttheworld();
}
}
// Tracing of alloc/free/gc.
static Lock tracelock;
static int8*
typeinfoname(int32 typeinfo)
{
if(typeinfo == TypeInfo_SingleObject)
return "single object";
else if(typeinfo == TypeInfo_Array)
return "array";
else if(typeinfo == TypeInfo_Chan)
return "channel";
runtime·throw("typinfoname: unknown type info");
return nil;
}
void
runtime·tracealloc(void *p, uintptr size, uintptr typ)
{
int8 *name;
Type *type;
runtime·lock(&tracelock);
m->traceback = 2;
type = (Type*)(typ & ~3);
name = typeinfoname(typ & 3);
if(type == nil)
runtime·printf("tracealloc(%p, %p, %s)\n", p, size, name);
else
runtime·printf("tracealloc(%p, %p, %s of %S)\n", p, size, name, *type->string);
if(m->curg == nil || g == m->curg) {
runtime·goroutineheader(g);
runtime·traceback((uintptr)runtime·getcallerpc(&p), (uintptr)runtime·getcallersp(&p), 0, g);
} else {
runtime·goroutineheader(m->curg);
runtime·traceback(~(uintptr)0, ~(uintptr)0, 0, m->curg);
}
runtime·printf("\n");
m->traceback = 0;
runtime·unlock(&tracelock);
}
void
runtime·tracefree(void *p, uintptr size)
{
runtime·lock(&tracelock);
m->traceback = 2;
runtime·printf("tracefree(%p, %p)\n", p, size);
runtime·goroutineheader(g);
runtime·traceback((uintptr)runtime·getcallerpc(&p), (uintptr)runtime·getcallersp(&p), 0, g);
runtime·printf("\n");
m->traceback = 0;
runtime·unlock(&tracelock);
}
void
runtime·tracegc(void)
{
runtime·lock(&tracelock);
m->traceback = 2;
runtime·printf("tracegc()\n");
// running on m->g0 stack; show all non-g0 goroutines
runtime·tracebackothers(g);
runtime·printf("end tracegc\n");
runtime·printf("\n");
m->traceback = 0;
runtime·unlock(&tracelock);
}