shithub: gefs

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blk: shard block locks by block address to reduce contention

--- a/blk.c

+++ b/blk.c

@@ -695,7 +695,6 @@

 	assert(b->type == Tsuper);

 	p = b->data;

-	setflag(b, Bdirty);

 	memcpy(p, "gefs0001", 8); p += 8;

 	PBIT32(p, Blksz); p += 4;

 	PBIT32(p, Bufspc); p += 4;

@@ -753,20 +752,22 @@

 Blk*

 getblk(Bptr bp, int flg)

 {

-	Blk *b;

 	uvlong h;

+	Blk *b;

+	int i;

 	if((b = lookupblk(bp.addr)) != nil)

 		return cacheblk(b);

-	qlock(&fs->blklk);

+	i = ihash(bp.addr) % nelem(fs->blklk);

+	qlock(&fs->blklk[i]);

 	if((b = lookupblk(bp.addr)) != nil){

 		cacheblk(b);

-		qunlock(&fs->blklk);

+		qunlock(&fs->blklk[i]);

 		return b;

 	}

 	if((b = readblk(bp.addr, flg)) == nil){

-		qunlock(&fs->blklk);

+		qunlock(&fs->blklk[i]);

 		return nil;

 	}else

 		setmalloctag(b, getcallerpc(&bp));

@@ -773,7 +774,7 @@

 	h = blkhash(b);

 	if((flg&GBnochk) == 0 && h != bp.hash){

 		fprint(2, "corrupt block %B: %llx != %llx\n", bp, blkhash(b), bp.hash);

-		qunlock(&fs->blklk);

+		qunlock(&fs->blklk[i]);

 		abort();

 		return nil;

 	}

@@ -780,7 +781,7 @@

 	b->bp.hash = h;

 	b->bp.gen = bp.gen;

 	cacheblk(b);

-	qunlock(&fs->blklk);

+	qunlock(&fs->blklk[i]);

 	return b;

 }

--- a/dat.h

+++ b/dat.h

@@ -451,7 +451,7 @@

 	Dent	*dtab[Ndtab];

 	/* slow block io */

-	QLock	blklk;

+	QLock	blklk[32];

 	/* protected by lrulk */

 	Lock	lrulk;