mirror of
https://github.com/golang/go
synced 2024-10-04 22:31:22 -06:00
6ee739d7e9
The issue was that scvg is assigned *after* the scavenger goroutine is started, so when the scavenger calls entersyscall() the g==scvg check can fail. Fixes #5025. R=golang-dev, iant CC=golang-dev https://golang.org/cl/7629045
536 lines
14 KiB
C
536 lines
14 KiB
C
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Page heap.
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//
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// See malloc.h for overview.
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//
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// When a MSpan is in the heap free list, state == MSpanFree
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// and heapmap(s->start) == span, heapmap(s->start+s->npages-1) == span.
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//
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// When a MSpan is allocated, state == MSpanInUse
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// and heapmap(i) == span for all s->start <= i < s->start+s->npages.
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#include "runtime.h"
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#include "arch_GOARCH.h"
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#include "malloc.h"
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static MSpan *MHeap_AllocLocked(MHeap*, uintptr, int32);
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static bool MHeap_Grow(MHeap*, uintptr);
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static void MHeap_FreeLocked(MHeap*, MSpan*);
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static MSpan *MHeap_AllocLarge(MHeap*, uintptr);
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static MSpan *BestFit(MSpan*, uintptr, MSpan*);
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static void
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RecordSpan(void *vh, byte *p)
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{
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MHeap *h;
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MSpan *s;
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MSpan **all;
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uint32 cap;
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h = vh;
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s = (MSpan*)p;
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if(h->nspan >= h->nspancap) {
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cap = 64*1024/sizeof(all[0]);
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if(cap < h->nspancap*3/2)
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cap = h->nspancap*3/2;
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all = (MSpan**)runtime·SysAlloc(cap*sizeof(all[0]));
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if(all == nil)
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runtime·throw("runtime: cannot allocate memory");
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if(h->allspans) {
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runtime·memmove(all, h->allspans, h->nspancap*sizeof(all[0]));
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runtime·SysFree(h->allspans, h->nspancap*sizeof(all[0]));
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}
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h->allspans = all;
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h->nspancap = cap;
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}
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h->allspans[h->nspan++] = s;
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}
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// Initialize the heap; fetch memory using alloc.
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void
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runtime·MHeap_Init(MHeap *h, void *(*alloc)(uintptr))
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{
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uint32 i;
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runtime·FixAlloc_Init(&h->spanalloc, sizeof(MSpan), alloc, RecordSpan, h);
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runtime·FixAlloc_Init(&h->cachealloc, sizeof(MCache), alloc, nil, nil);
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// h->mapcache needs no init
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for(i=0; i<nelem(h->free); i++)
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runtime·MSpanList_Init(&h->free[i]);
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runtime·MSpanList_Init(&h->large);
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for(i=0; i<nelem(h->central); i++)
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runtime·MCentral_Init(&h->central[i], i);
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}
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// Allocate a new span of npage pages from the heap
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// and record its size class in the HeapMap and HeapMapCache.
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MSpan*
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runtime·MHeap_Alloc(MHeap *h, uintptr npage, int32 sizeclass, int32 acct, int32 zeroed)
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{
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MSpan *s;
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runtime·lock(h);
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runtime·purgecachedstats(m->mcache);
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s = MHeap_AllocLocked(h, npage, sizeclass);
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if(s != nil) {
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mstats.heap_inuse += npage<<PageShift;
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if(acct) {
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mstats.heap_objects++;
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mstats.heap_alloc += npage<<PageShift;
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}
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}
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runtime·unlock(h);
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if(s != nil && *(uintptr*)(s->start<<PageShift) != 0 && zeroed)
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runtime·memclr((byte*)(s->start<<PageShift), s->npages<<PageShift);
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return s;
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}
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static MSpan*
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MHeap_AllocLocked(MHeap *h, uintptr npage, int32 sizeclass)
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{
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uintptr n;
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MSpan *s, *t;
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PageID p;
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// Try in fixed-size lists up to max.
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for(n=npage; n < nelem(h->free); n++) {
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if(!runtime·MSpanList_IsEmpty(&h->free[n])) {
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s = h->free[n].next;
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goto HaveSpan;
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}
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}
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// Best fit in list of large spans.
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if((s = MHeap_AllocLarge(h, npage)) == nil) {
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if(!MHeap_Grow(h, npage))
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return nil;
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if((s = MHeap_AllocLarge(h, npage)) == nil)
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return nil;
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}
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HaveSpan:
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// Mark span in use.
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if(s->state != MSpanFree)
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runtime·throw("MHeap_AllocLocked - MSpan not free");
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if(s->npages < npage)
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runtime·throw("MHeap_AllocLocked - bad npages");
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runtime·MSpanList_Remove(s);
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s->state = MSpanInUse;
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mstats.heap_idle -= s->npages<<PageShift;
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mstats.heap_released -= s->npreleased<<PageShift;
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s->npreleased = 0;
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if(s->npages > npage) {
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// Trim extra and put it back in the heap.
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t = runtime·FixAlloc_Alloc(&h->spanalloc);
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mstats.mspan_inuse = h->spanalloc.inuse;
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mstats.mspan_sys = h->spanalloc.sys;
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runtime·MSpan_Init(t, s->start + npage, s->npages - npage);
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s->npages = npage;
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p = t->start;
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if(sizeof(void*) == 8)
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p -= ((uintptr)h->arena_start>>PageShift);
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if(p > 0)
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h->map[p-1] = s;
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h->map[p] = t;
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h->map[p+t->npages-1] = t;
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*(uintptr*)(t->start<<PageShift) = *(uintptr*)(s->start<<PageShift); // copy "needs zeroing" mark
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t->state = MSpanInUse;
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MHeap_FreeLocked(h, t);
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t->unusedsince = s->unusedsince; // preserve age
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}
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s->unusedsince = 0;
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// Record span info, because gc needs to be
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// able to map interior pointer to containing span.
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s->sizeclass = sizeclass;
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s->elemsize = (sizeclass==0 ? s->npages<<PageShift : runtime·class_to_size[sizeclass]);
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s->types.compression = MTypes_Empty;
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p = s->start;
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if(sizeof(void*) == 8)
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p -= ((uintptr)h->arena_start>>PageShift);
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for(n=0; n<npage; n++)
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h->map[p+n] = s;
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return s;
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}
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// Allocate a span of exactly npage pages from the list of large spans.
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static MSpan*
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MHeap_AllocLarge(MHeap *h, uintptr npage)
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{
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return BestFit(&h->large, npage, nil);
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}
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// Search list for smallest span with >= npage pages.
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// If there are multiple smallest spans, take the one
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// with the earliest starting address.
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static MSpan*
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BestFit(MSpan *list, uintptr npage, MSpan *best)
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{
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MSpan *s;
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for(s=list->next; s != list; s=s->next) {
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if(s->npages < npage)
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continue;
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if(best == nil
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|| s->npages < best->npages
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|| (s->npages == best->npages && s->start < best->start))
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best = s;
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}
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return best;
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}
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// Try to add at least npage pages of memory to the heap,
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// returning whether it worked.
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static bool
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MHeap_Grow(MHeap *h, uintptr npage)
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{
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uintptr ask;
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void *v;
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MSpan *s;
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PageID p;
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// Ask for a big chunk, to reduce the number of mappings
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// the operating system needs to track; also amortizes
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// the overhead of an operating system mapping.
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// Allocate a multiple of 64kB (16 pages).
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npage = (npage+15)&~15;
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ask = npage<<PageShift;
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if(ask < HeapAllocChunk)
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ask = HeapAllocChunk;
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v = runtime·MHeap_SysAlloc(h, ask);
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if(v == nil) {
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if(ask > (npage<<PageShift)) {
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ask = npage<<PageShift;
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v = runtime·MHeap_SysAlloc(h, ask);
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}
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if(v == nil) {
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runtime·printf("runtime: out of memory: cannot allocate %D-byte block (%D in use)\n", (uint64)ask, mstats.heap_sys);
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return false;
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}
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}
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mstats.heap_sys += ask;
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// Create a fake "in use" span and free it, so that the
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// right coalescing happens.
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s = runtime·FixAlloc_Alloc(&h->spanalloc);
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mstats.mspan_inuse = h->spanalloc.inuse;
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mstats.mspan_sys = h->spanalloc.sys;
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runtime·MSpan_Init(s, (uintptr)v>>PageShift, ask>>PageShift);
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p = s->start;
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if(sizeof(void*) == 8)
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p -= ((uintptr)h->arena_start>>PageShift);
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h->map[p] = s;
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h->map[p + s->npages - 1] = s;
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s->state = MSpanInUse;
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MHeap_FreeLocked(h, s);
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return true;
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}
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// Look up the span at the given address.
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// Address is guaranteed to be in map
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// and is guaranteed to be start or end of span.
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MSpan*
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runtime·MHeap_Lookup(MHeap *h, void *v)
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{
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uintptr p;
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p = (uintptr)v;
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if(sizeof(void*) == 8)
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p -= (uintptr)h->arena_start;
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return h->map[p >> PageShift];
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}
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// Look up the span at the given address.
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// Address is *not* guaranteed to be in map
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// and may be anywhere in the span.
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// Map entries for the middle of a span are only
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// valid for allocated spans. Free spans may have
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// other garbage in their middles, so we have to
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// check for that.
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MSpan*
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runtime·MHeap_LookupMaybe(MHeap *h, void *v)
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{
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MSpan *s;
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PageID p, q;
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if((byte*)v < h->arena_start || (byte*)v >= h->arena_used)
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return nil;
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p = (uintptr)v>>PageShift;
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q = p;
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if(sizeof(void*) == 8)
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q -= (uintptr)h->arena_start >> PageShift;
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s = h->map[q];
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if(s == nil || p < s->start || p - s->start >= s->npages)
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return nil;
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if(s->state != MSpanInUse)
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return nil;
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return s;
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}
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// Free the span back into the heap.
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void
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runtime·MHeap_Free(MHeap *h, MSpan *s, int32 acct)
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{
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runtime·lock(h);
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runtime·purgecachedstats(m->mcache);
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mstats.heap_inuse -= s->npages<<PageShift;
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if(acct) {
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mstats.heap_alloc -= s->npages<<PageShift;
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mstats.heap_objects--;
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}
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MHeap_FreeLocked(h, s);
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runtime·unlock(h);
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}
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static void
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MHeap_FreeLocked(MHeap *h, MSpan *s)
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{
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uintptr *sp, *tp;
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MSpan *t;
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PageID p;
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if(s->types.sysalloc)
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runtime·settype_sysfree(s);
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s->types.compression = MTypes_Empty;
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if(s->state != MSpanInUse || s->ref != 0) {
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runtime·printf("MHeap_FreeLocked - span %p ptr %p state %d ref %d\n", s, s->start<<PageShift, s->state, s->ref);
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runtime·throw("MHeap_FreeLocked - invalid free");
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}
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mstats.heap_idle += s->npages<<PageShift;
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s->state = MSpanFree;
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runtime·MSpanList_Remove(s);
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sp = (uintptr*)(s->start<<PageShift);
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// Stamp newly unused spans. The scavenger will use that
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// info to potentially give back some pages to the OS.
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s->unusedsince = runtime·nanotime();
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s->npreleased = 0;
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// Coalesce with earlier, later spans.
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p = s->start;
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if(sizeof(void*) == 8)
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p -= (uintptr)h->arena_start >> PageShift;
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if(p > 0 && (t = h->map[p-1]) != nil && t->state != MSpanInUse) {
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tp = (uintptr*)(t->start<<PageShift);
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*tp |= *sp; // propagate "needs zeroing" mark
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s->start = t->start;
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s->npages += t->npages;
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s->npreleased = t->npreleased; // absorb released pages
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p -= t->npages;
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h->map[p] = s;
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runtime·MSpanList_Remove(t);
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t->state = MSpanDead;
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runtime·FixAlloc_Free(&h->spanalloc, t);
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mstats.mspan_inuse = h->spanalloc.inuse;
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mstats.mspan_sys = h->spanalloc.sys;
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}
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if(p+s->npages < nelem(h->map) && (t = h->map[p+s->npages]) != nil && t->state != MSpanInUse) {
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tp = (uintptr*)(t->start<<PageShift);
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*sp |= *tp; // propagate "needs zeroing" mark
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s->npages += t->npages;
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s->npreleased += t->npreleased;
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h->map[p + s->npages - 1] = s;
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runtime·MSpanList_Remove(t);
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t->state = MSpanDead;
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runtime·FixAlloc_Free(&h->spanalloc, t);
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mstats.mspan_inuse = h->spanalloc.inuse;
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mstats.mspan_sys = h->spanalloc.sys;
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}
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// Insert s into appropriate list.
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if(s->npages < nelem(h->free))
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runtime·MSpanList_Insert(&h->free[s->npages], s);
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else
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runtime·MSpanList_Insert(&h->large, s);
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}
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static void
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forcegchelper(Note *note)
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{
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runtime·gc(1);
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runtime·notewakeup(note);
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}
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static uintptr
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scavengelist(MSpan *list, uint64 now, uint64 limit)
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{
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uintptr released, sumreleased;
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MSpan *s;
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if(runtime·MSpanList_IsEmpty(list))
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return 0;
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sumreleased = 0;
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for(s=list->next; s != list; s=s->next) {
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if((now - s->unusedsince) > limit) {
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released = (s->npages - s->npreleased) << PageShift;
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mstats.heap_released += released;
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sumreleased += released;
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s->npreleased = s->npages;
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runtime·SysUnused((void*)(s->start << PageShift), s->npages << PageShift);
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}
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}
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return sumreleased;
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}
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static uintptr
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scavenge(uint64 now, uint64 limit)
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{
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uint32 i;
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uintptr sumreleased;
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MHeap *h;
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h = runtime·mheap;
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sumreleased = 0;
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for(i=0; i < nelem(h->free); i++)
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sumreleased += scavengelist(&h->free[i], now, limit);
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sumreleased += scavengelist(&h->large, now, limit);
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return sumreleased;
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}
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static FuncVal forcegchelperv = {(void(*)(void))forcegchelper};
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// Release (part of) unused memory to OS.
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// Goroutine created at startup.
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// Loop forever.
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void
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runtime·MHeap_Scavenger(void)
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{
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MHeap *h;
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uint64 tick, now, forcegc, limit;
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uint32 k;
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uintptr sumreleased;
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byte *env;
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bool trace;
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Note note, *notep;
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g->issystem = true;
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g->isbackground = true;
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// If we go two minutes without a garbage collection, force one to run.
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forcegc = 2*60*1e9;
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// If a span goes unused for 5 minutes after a garbage collection,
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// we hand it back to the operating system.
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limit = 5*60*1e9;
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// Make wake-up period small enough for the sampling to be correct.
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if(forcegc < limit)
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tick = forcegc/2;
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else
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tick = limit/2;
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trace = false;
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env = runtime·getenv("GOGCTRACE");
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if(env != nil)
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trace = runtime·atoi(env) > 0;
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h = runtime·mheap;
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for(k=0;; k++) {
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runtime·noteclear(¬e);
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runtime·entersyscallblock();
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runtime·notetsleep(¬e, tick);
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runtime·exitsyscall();
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runtime·lock(h);
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now = runtime·nanotime();
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if(now - mstats.last_gc > forcegc) {
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runtime·unlock(h);
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// The scavenger can not block other goroutines,
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// otherwise deadlock detector can fire spuriously.
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// GC blocks other goroutines via the runtime·worldsema.
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runtime·noteclear(¬e);
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notep = ¬e;
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runtime·newproc1(&forcegchelperv, (byte*)¬ep, sizeof(notep), 0, runtime·MHeap_Scavenger);
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runtime·entersyscallblock();
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runtime·notesleep(¬e);
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runtime·exitsyscall();
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if(trace)
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runtime·printf("scvg%d: GC forced\n", k);
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runtime·lock(h);
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now = runtime·nanotime();
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}
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sumreleased = scavenge(now, limit);
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runtime·unlock(h);
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if(trace) {
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if(sumreleased > 0)
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runtime·printf("scvg%d: %p MB released\n", k, sumreleased>>20);
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runtime·printf("scvg%d: inuse: %D, idle: %D, sys: %D, released: %D, consumed: %D (MB)\n",
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k, mstats.heap_inuse>>20, mstats.heap_idle>>20, mstats.heap_sys>>20,
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mstats.heap_released>>20, (mstats.heap_sys - mstats.heap_released)>>20);
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}
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}
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}
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void
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runtime∕debug·freeOSMemory(void)
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{
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runtime·gc(1);
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runtime·lock(runtime·mheap);
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scavenge(~(uintptr)0, 0);
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runtime·unlock(runtime·mheap);
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}
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// Initialize a new span with the given start and npages.
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void
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runtime·MSpan_Init(MSpan *span, PageID start, uintptr npages)
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{
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span->next = nil;
|
||
span->prev = nil;
|
||
span->start = start;
|
||
span->npages = npages;
|
||
span->freelist = nil;
|
||
span->ref = 0;
|
||
span->sizeclass = 0;
|
||
span->elemsize = 0;
|
||
span->state = 0;
|
||
span->unusedsince = 0;
|
||
span->npreleased = 0;
|
||
span->types.compression = MTypes_Empty;
|
||
}
|
||
|
||
// Initialize an empty doubly-linked list.
|
||
void
|
||
runtime·MSpanList_Init(MSpan *list)
|
||
{
|
||
list->state = MSpanListHead;
|
||
list->next = list;
|
||
list->prev = list;
|
||
}
|
||
|
||
void
|
||
runtime·MSpanList_Remove(MSpan *span)
|
||
{
|
||
if(span->prev == nil && span->next == nil)
|
||
return;
|
||
span->prev->next = span->next;
|
||
span->next->prev = span->prev;
|
||
span->prev = nil;
|
||
span->next = nil;
|
||
}
|
||
|
||
bool
|
||
runtime·MSpanList_IsEmpty(MSpan *list)
|
||
{
|
||
return list->next == list;
|
||
}
|
||
|
||
void
|
||
runtime·MSpanList_Insert(MSpan *list, MSpan *span)
|
||
{
|
||
if(span->next != nil || span->prev != nil) {
|
||
runtime·printf("failed MSpanList_Insert %p %p %p\n", span, span->next, span->prev);
|
||
runtime·throw("MSpanList_Insert");
|
||
}
|
||
span->next = list->next;
|
||
span->prev = list;
|
||
span->next->prev = span;
|
||
span->prev->next = span;
|
||
}
|
||
|
||
|