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go/src/pkg/runtime/stack.c
Dmitriy Vyukov a33ef8d11b runtime: account for all sys memory in MemStats
Currently lots of sys allocations are not accounted in any of XxxSys,
including GC bitmap, spans table, GC roots blocks, GC finalizer blocks,
iface table, netpoll descriptors and more. Up to ~20% can unaccounted.
This change introduces 2 new stats: GCSys and OtherSys for GC metadata
and all other misc allocations, respectively.
Also ensures that all XxxSys indeed sum up to Sys. All sys memory allocation
functions require the stat for accounting, so that it's impossible to miss something.
Also fix updating of mcache_sys/inuse, they were not updated after deallocation.

test/bench/garbage/parser before:
Sys		670064344
HeapSys		610271232
StackSys	65536
MSpanSys	14204928
MCacheSys	16384
BuckHashSys	1439992

after:
Sys		670064344
HeapSys		610271232
StackSys	65536
MSpanSys	14188544
MCacheSys	16384
BuckHashSys	3194304
GCSys		39198688
OtherSys	3129656

Fixes #5799.

R=rsc, dave, alex.brainman
CC=golang-dev
https://golang.org/cl/12946043
2013-09-06 16:55:40 -04:00

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// Copyright 2013 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.
#include "runtime.h"
#include "arch_GOARCH.h"
#include "malloc.h"
#include "stack.h"
enum
{
StackDebug = 0,
};
typedef struct StackCacheNode StackCacheNode;
struct StackCacheNode
{
StackCacheNode *next;
void* batch[StackCacheBatch-1];
};
static StackCacheNode *stackcache;
static Lock stackcachemu;
// stackcacherefill/stackcacherelease implement a global cache of stack segments.
// The cache is required to prevent unlimited growth of per-thread caches.
static void
stackcacherefill(void)
{
StackCacheNode *n;
int32 i, pos;
runtime·lock(&stackcachemu);
n = stackcache;
if(n)
stackcache = n->next;
runtime·unlock(&stackcachemu);
if(n == nil) {
n = (StackCacheNode*)runtime·SysAlloc(FixedStack*StackCacheBatch, &mstats.stacks_sys);
if(n == nil)
runtime·throw("out of memory (stackcacherefill)");
for(i = 0; i < StackCacheBatch-1; i++)
n->batch[i] = (byte*)n + (i+1)*FixedStack;
}
pos = m->stackcachepos;
for(i = 0; i < StackCacheBatch-1; i++) {
m->stackcache[pos] = n->batch[i];
pos = (pos + 1) % StackCacheSize;
}
m->stackcache[pos] = n;
pos = (pos + 1) % StackCacheSize;
m->stackcachepos = pos;
m->stackcachecnt += StackCacheBatch;
}
static void
stackcacherelease(void)
{
StackCacheNode *n;
uint32 i, pos;
pos = (m->stackcachepos - m->stackcachecnt) % StackCacheSize;
n = (StackCacheNode*)m->stackcache[pos];
pos = (pos + 1) % StackCacheSize;
for(i = 0; i < StackCacheBatch-1; i++) {
n->batch[i] = m->stackcache[pos];
pos = (pos + 1) % StackCacheSize;
}
m->stackcachecnt -= StackCacheBatch;
runtime·lock(&stackcachemu);
n->next = stackcache;
stackcache = n;
runtime·unlock(&stackcachemu);
}
void*
runtime·stackalloc(uint32 n)
{
uint32 pos;
void *v;
// Stackalloc must be called on scheduler stack, so that we
// never try to grow the stack during the code that stackalloc runs.
// Doing so would cause a deadlock (issue 1547).
if(g != m->g0)
runtime·throw("stackalloc not on scheduler stack");
// Stacks are usually allocated with a fixed-size free-list allocator,
// but if we need a stack of non-standard size, we fall back on malloc
// (assuming that inside malloc and GC all the stack frames are small,
// so that we do not deadlock).
if(n == FixedStack || m->mallocing || m->gcing) {
if(n != FixedStack) {
runtime·printf("stackalloc: in malloc, size=%d want %d\n", FixedStack, n);
runtime·throw("stackalloc");
}
if(m->stackcachecnt == 0)
stackcacherefill();
pos = m->stackcachepos;
pos = (pos - 1) % StackCacheSize;
v = m->stackcache[pos];
m->stackcachepos = pos;
m->stackcachecnt--;
m->stackinuse++;
return v;
}
return runtime·mallocgc(n, 0, FlagNoProfiling|FlagNoGC|FlagNoZero|FlagNoInvokeGC);
}
void
runtime·stackfree(void *v, uintptr n)
{
uint32 pos;
if(n == FixedStack || m->mallocing || m->gcing) {
if(m->stackcachecnt == StackCacheSize)
stackcacherelease();
pos = m->stackcachepos;
m->stackcache[pos] = v;
m->stackcachepos = (pos + 1) % StackCacheSize;
m->stackcachecnt++;
m->stackinuse--;
return;
}
runtime·free(v);
}
// Called from runtime·lessstack when returning from a function which
// allocated a new stack segment. The function's return value is in
// m->cret.
void
runtime·oldstack(void)
{
Stktop *top;
uint32 argsize;
byte *sp, *old;
uintptr *src, *dst, *dstend;
G *gp;
int64 goid;
int32 oldstatus;
gp = m->curg;
top = (Stktop*)gp->stackbase;
old = (byte*)gp->stackguard - StackGuard;
sp = (byte*)top;
argsize = top->argsize;
if(StackDebug) {
runtime·printf("runtime: oldstack gobuf={pc:%p sp:%p lr:%p} cret=%p argsize=%p\n",
top->gobuf.pc, top->gobuf.sp, top->gobuf.lr, m->cret, (uintptr)argsize);
}
// gp->status is usually Grunning, but it could be Gsyscall if a stack split
// happens during a function call inside entersyscall.
oldstatus = gp->status;
gp->sched = top->gobuf;
gp->sched.ret = m->cret;
m->cret = 0; // drop reference
gp->status = Gwaiting;
gp->waitreason = "stack unsplit";
if(argsize > 0) {
sp -= argsize;
dst = (uintptr*)top->argp;
dstend = dst + argsize/sizeof(*dst);
src = (uintptr*)sp;
while(dst < dstend)
*dst++ = *src++;
}
goid = top->gobuf.g->goid; // fault if g is bad, before gogo
USED(goid);
gp->stackbase = top->stackbase;
gp->stackguard = top->stackguard;
gp->stackguard0 = gp->stackguard;
if(top->free != 0) {
gp->stacksize -= top->free;
runtime·stackfree(old, top->free);
}
gp->status = oldstatus;
runtime·gogo(&gp->sched);
}
uintptr runtime·maxstacksize = 1<<20; // enough until runtime.main sets it for real
// Called from runtime·newstackcall or from runtime·morestack when a new
// stack segment is needed. Allocate a new stack big enough for
// m->moreframesize bytes, copy m->moreargsize bytes to the new frame,
// and then act as though runtime·lessstack called the function at
// m->morepc.
void
runtime·newstack(void)
{
int32 framesize, argsize, oldstatus;
Stktop *top;
byte *stk;
uintptr sp;
uintptr *src, *dst, *dstend;
G *gp;
Gobuf label;
bool newstackcall;
uintptr free;
if(m->morebuf.g != m->curg) {
runtime·printf("runtime: newstack called from g=%p\n"
"\tm=%p m->curg=%p m->g0=%p m->gsignal=%p\n",
m->morebuf.g, m, m->curg, m->g0, m->gsignal);
runtime·throw("runtime: wrong goroutine in newstack");
}
// gp->status is usually Grunning, but it could be Gsyscall if a stack split
// happens during a function call inside entersyscall.
gp = m->curg;
oldstatus = gp->status;
framesize = m->moreframesize;
argsize = m->moreargsize;
gp->status = Gwaiting;
gp->waitreason = "stack split";
newstackcall = framesize==1;
if(newstackcall)
framesize = 0;
// For newstackcall the context already points to beginning of runtime·newstackcall.
if(!newstackcall)
runtime·rewindmorestack(&gp->sched);
sp = gp->sched.sp;
if(thechar == '6' || thechar == '8') {
// The call to morestack cost a word.
sp -= sizeof(uintptr);
}
if(StackDebug || sp < gp->stackguard - StackGuard) {
runtime·printf("runtime: newstack framesize=%p argsize=%p sp=%p stack=[%p, %p]\n"
"\tmorebuf={pc:%p sp:%p lr:%p}\n"
"\tsched={pc:%p sp:%p lr:%p ctxt:%p}\n",
(uintptr)framesize, (uintptr)argsize, sp, gp->stackguard - StackGuard, gp->stackbase,
m->morebuf.pc, m->morebuf.sp, m->morebuf.lr,
gp->sched.pc, gp->sched.sp, gp->sched.lr, gp->sched.ctxt);
}
if(sp < gp->stackguard - StackGuard) {
runtime·printf("runtime: split stack overflow: %p < %p\n", sp, gp->stackguard - StackGuard);
runtime·throw("runtime: split stack overflow");
}
if(argsize % sizeof(uintptr) != 0) {
runtime·printf("runtime: stack split with misaligned argsize %d\n", argsize);
runtime·throw("runtime: stack split argsize");
}
if(gp->stackguard0 == (uintptr)StackPreempt) {
if(gp == m->g0)
runtime·throw("runtime: preempt g0");
if(oldstatus == Grunning && m->p == nil)
runtime·throw("runtime: g is running but p is not");
if(oldstatus == Gsyscall && m->locks == 0)
runtime·throw("runtime: stack split during syscall");
// Be conservative about where we preempt.
// We are interested in preempting user Go code, not runtime code.
if(oldstatus != Grunning || m->locks || m->mallocing || m->gcing || m->p->status != Prunning) {
// Let the goroutine keep running for now.
// gp->preempt is set, so it will be preempted next time.
gp->stackguard0 = gp->stackguard;
gp->status = oldstatus;
runtime·gogo(&gp->sched); // never return
}
// Act like goroutine called runtime.Gosched.
gp->status = oldstatus;
runtime·gosched0(gp); // never return
}
if(newstackcall && m->morebuf.sp - sizeof(Stktop) - argsize - 32 > gp->stackguard) {
// special case: called from runtime.newstackcall (framesize==1)
// to call code with an arbitrary argument size,
// and we have enough space on the current stack.
// the new Stktop* is necessary to unwind, but
// we don't need to create a new segment.
top = (Stktop*)(m->morebuf.sp - sizeof(*top));
stk = (byte*)gp->stackguard - StackGuard;
free = 0;
} else {
// allocate new segment.
framesize += argsize;
framesize += StackExtra; // room for more functions, Stktop.
if(framesize < StackMin)
framesize = StackMin;
framesize += StackSystem;
gp->stacksize += framesize;
if(gp->stacksize > runtime·maxstacksize) {
runtime·printf("runtime: goroutine stack exceeds %D-byte limit\n", (uint64)runtime·maxstacksize);
runtime·throw("stack overflow");
}
stk = runtime·stackalloc(framesize);
top = (Stktop*)(stk+framesize-sizeof(*top));
free = framesize;
}
if(StackDebug) {
runtime·printf("\t-> new stack [%p, %p]\n", stk, top);
}
top->stackbase = gp->stackbase;
top->stackguard = gp->stackguard;
top->gobuf = m->morebuf;
top->argp = m->moreargp;
top->argsize = argsize;
top->free = free;
m->moreargp = nil;
m->morebuf.pc = (uintptr)nil;
m->morebuf.lr = (uintptr)nil;
m->morebuf.sp = (uintptr)nil;
// copy flag from panic
top->panic = gp->ispanic;
gp->ispanic = false;
gp->stackbase = (uintptr)top;
gp->stackguard = (uintptr)stk + StackGuard;
gp->stackguard0 = gp->stackguard;
sp = (uintptr)top;
if(argsize > 0) {
sp -= argsize;
dst = (uintptr*)sp;
dstend = dst + argsize/sizeof(*dst);
src = (uintptr*)top->argp;
while(dst < dstend)
*dst++ = *src++;
}
if(thechar == '5') {
// caller would have saved its LR below args.
sp -= sizeof(void*);
*(void**)sp = nil;
}
// Continue as if lessstack had just called m->morepc
// (the PC that decided to grow the stack).
runtime·memclr((byte*)&label, sizeof label);
label.sp = sp;
label.pc = (uintptr)runtime·lessstack;
label.g = m->curg;
if(newstackcall)
runtime·gostartcallfn(&label, (FuncVal*)m->cret);
else {
runtime·gostartcall(&label, (void(*)(void))gp->sched.pc, gp->sched.ctxt);
gp->sched.ctxt = nil;
}
gp->status = oldstatus;
runtime·gogo(&label);
*(int32*)345 = 123; // never return
}
// adjust Gobuf as if it executed a call to fn
// and then did an immediate gosave.
void
runtime·gostartcallfn(Gobuf *gobuf, FuncVal *fv)
{
runtime·gostartcall(gobuf, fv->fn, fv);
}
void
runtimedebug·setMaxStack(intgo in, intgo out)
{
out = runtime·maxstacksize;
runtime·maxstacksize = in;
FLUSH(&out);
}