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runtime: replace lock() with casp() in the GC

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Note: BitTarget will be removed by a forthcoming changeset.

R=golang-dev, dvyukov
CC=golang-dev, rsc
https://golang.org/cl/7837044
This commit is contained in:
Jan Ziak 2013-03-15 09:02:36 +01:00
parent 175c401523
commit 2924638d26
1 changed files with 29 additions and 31 deletions
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60
src/pkg/runtime/mgc0.c
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@ -191,7 +191,7 @@ static struct {
// markonly marks an object. It returns true if the object
// has been marked by this function, false otherwise.
// This function isn't thread-safe and doesn't append the object to any buffer.
// This function doesn't append the object to any buffer.
static bool
markonly(void *obj)
{
@ -254,7 +254,17 @@ found:
// Only care about allocated and not marked.
if((bits & (bitAllocated|bitMarked)) != bitAllocated)
return false;
*bitp |= bitMarked<<shift;
if(work.nproc == 1)
*bitp |= bitMarked<<shift;
else {
for(;;) {
x = *bitp;
if(x & (bitMarked<<shift))
return false;
if(runtime·casp((void**)bitp, (void*)x, (void*)(x|(bitMarked<<shift))))
break;
}
}
// The object is now marked
return true;
@ -325,7 +335,6 @@ flushptrbuf(PtrTarget *ptrbuf, PtrTarget **ptrbufpos, Obj **_wp, Workbuf **_wbuf
Obj *wp;
Workbuf *wbuf;
PtrTarget *ptrbuf_end;
BitTarget *bitbufpos, *bt;
arena_start = runtime·mheap->arena_start;
@ -359,8 +368,6 @@ flushptrbuf(PtrTarget *ptrbuf, PtrTarget **ptrbufpos, Obj **_wp, Workbuf **_wbuf
{
// Multi-threaded version.
bitbufpos = bitbuf;
while(ptrbuf < ptrbuf_end) {
obj = ptrbuf->p;
ti = ptrbuf->ti;
@ -438,26 +445,22 @@ flushptrbuf(PtrTarget *ptrbuf, PtrTarget **ptrbufpos, Obj **_wp, Workbuf **_wbuf
// Only care about allocated and not marked.
if((bits & (bitAllocated|bitMarked)) != bitAllocated)
continue;
*bitbufpos++ = (BitTarget){obj, ti, bitp, shift};
}
runtime·lock(&lock);
for(bt=bitbuf; bt<bitbufpos; bt++){
xbits = *bt->bitp;
bits = xbits >> bt->shift;
if((bits & bitMarked) != 0)
continue;
// Mark the block
*bt->bitp = xbits | (bitMarked << bt->shift);
if(work.nproc == 1)
*bitp |= bitMarked<<shift;
else {
for(;;) {
x = *bitp;
if(x & (bitMarked<<shift))
goto continue_obj;
if(runtime·casp((void**)bitp, (void*)x, (void*)(x|(bitMarked<<shift))))
break;
}
}
// If object has no pointers, don't need to scan further.
if((bits & bitNoPointers) != 0)
continue;
obj = bt->p;
// Ask span about size class.
// (Manually inlined copy of MHeap_Lookup.)
x = (uintptr)obj >> PageShift;
@ -467,11 +470,11 @@ flushptrbuf(PtrTarget *ptrbuf, PtrTarget **ptrbufpos, Obj **_wp, Workbuf **_wbuf
PREFETCH(obj);
*wp = (Obj){obj, s->elemsize, bt->ti};
*wp = (Obj){obj, s->elemsize, ti};
wp++;
nobj++;
continue_obj:;
}
runtime·unlock(&lock);
// If another proc wants a pointer, give it some.
if(work.nwait > 0 && nobj > handoffThreshold && work.full == 0) {
@ -588,7 +591,7 @@ scanblock(Workbuf *wbuf, Obj *wp, uintptr nobj, bool keepworking)
Iface *iface;
Hmap *hmap;
MapType *maptype;
bool didmark, mapkey_kind, mapval_kind;
bool mapkey_kind, mapval_kind;
struct hash_gciter map_iter;
struct hash_gciter_data d;
Hchan *chan;
@ -894,10 +897,7 @@ scanblock(Workbuf *wbuf, Obj *wp, uintptr nobj, bool keepworking)
pc += 3;
continue;
}
runtime·lock(&lock);
didmark = markonly(hmap);
runtime·unlock(&lock);
if(didmark) {
if(markonly(hmap)) {
maptype = (MapType*)pc[2];
if(hash_gciter_init(hmap, &map_iter)) {
mapkey_size = maptype->key->size;
@ -927,11 +927,9 @@ scanblock(Workbuf *wbuf, Obj *wp, uintptr nobj, bool keepworking)
if(objbufpos+2 >= objbuf_end)
flushobjbuf(objbuf, &objbufpos, &wp, &wbuf, &nobj);
if(d.st != nil) {
runtime·lock(&lock);
if(d.st != nil)
markonly(d.st);
runtime·unlock(&lock);
}
if(d.key_data != nil) {
if(!(mapkey_kind & KindNoPointers) || d.indirectkey) {
if(!d.indirectkey)