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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.
// Per-P malloc cache for small objects.
//
// See malloc.h for an overview.
#include "runtime.h"
#include "arch.h"
#include "malloc.h"
extern volatile intgo runtime_MemProfileRate
__asm__ (GOSYM_PREFIX "runtime.MemProfileRate");
// dummy MSpan that contains no free objects.
static MSpan emptymspan;
MCache*
runtime_allocmcache(void)
{
intgo rate;
MCache *c;
int32 i;
runtime_lock(&runtime_mheap);
c = runtime_FixAlloc_Alloc(&runtime_mheap.cachealloc);
runtime_unlock(&runtime_mheap);
runtime_memclr((byte*)c, sizeof(*c));
for(i = 0; i < _NumSizeClasses; i++)
c->alloc[i] = &emptymspan;
// Set first allocation sample size.
rate = runtime_MemProfileRate;
if(rate > 0x3fffffff) // make 2*rate not overflow
rate = 0x3fffffff;
if(rate != 0)
c->next_sample = runtime_fastrand1() % (2*rate);
return c;
}
void
runtime_freemcache(MCache *c)
{
runtime_MCache_ReleaseAll(c);
runtime_lock(&runtime_mheap);
runtime_purgecachedstats(c);
runtime_FixAlloc_Free(&runtime_mheap.cachealloc, c);
runtime_unlock(&runtime_mheap);
}
// Gets a span that has a free object in it and assigns it
// to be the cached span for the given sizeclass. Returns this span.
MSpan*
runtime_MCache_Refill(MCache *c, int32 sizeclass)
{
MCacheList *l;
MSpan *s;
runtime_m()->locks++;
// Return the current cached span to the central lists.
s = c->alloc[sizeclass];
if(s->freelist != nil)
runtime_throw("refill on a nonempty span");
if(s != &emptymspan)
runtime_MCentral_UncacheSpan(&runtime_mheap.central[sizeclass], s);
// Push any explicitly freed objects to the central lists.
// Not required, but it seems like a good time to do it.
l = &c->free[sizeclass];
if(l->nlist > 0) {
runtime_MCentral_FreeList(&runtime_mheap.central[sizeclass], l->list);
l->list = nil;
l->nlist = 0;
}
// Get a new cached span from the central lists.
s = runtime_MCentral_CacheSpan(&runtime_mheap.central[sizeclass]);
if(s == nil)
runtime_throw("out of memory");
if(s->freelist == nil) {
runtime_printf("%d %d\n", s->ref, (int32)((s->npages << PageShift) / s->elemsize));
runtime_throw("empty span");
}
c->alloc[sizeclass] = s;
runtime_m()->locks--;
return s;
}
void
runtime_MCache_Free(MCache *c, MLink *p, int32 sizeclass, uintptr size)
{
MCacheList *l;
// Put on free list.
l = &c->free[sizeclass];
p->next = l->list;
l->list = p;
l->nlist++;
// We transfer a span at a time from MCentral to MCache,
// so we'll do the same in the other direction.
if(l->nlist >= (runtime_class_to_allocnpages[sizeclass]<<PageShift)/size) {
runtime_MCentral_FreeList(&runtime_mheap.central[sizeclass], l->list);
l->list = nil;
l->nlist = 0;
}
}
void
runtime_MCache_ReleaseAll(MCache *c)
{
int32 i;
MSpan *s;
MCacheList *l;
for(i=0; i<_NumSizeClasses; i++) {
s = c->alloc[i];
if(s != &emptymspan) {
runtime_MCentral_UncacheSpan(&runtime_mheap.central[i], s);
c->alloc[i] = &emptymspan;
}
l = &c->free[i];
if(l->nlist > 0) {
runtime_MCentral_FreeList(&runtime_mheap.central[i], l->list);
l->list = nil;
l->nlist = 0;
}
}
}
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