shithub: neoventi

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cache: remove free list

--- a/cache.c

+++ b/cache.c

@@ -16,8 +16,7 @@

 static char *data;

 static bucket_t *buckets, *bucketend;

-static u32int *freelist;

-static u32int freelen;

+static u32int freebufs;

 static Lock freelock;

 enum {

@@ -40,8 +39,8 @@

 	// when selecting the portion of the fibonacci hash to use, so it's

 	// not strictly Fibonacci hashing that requires power-of-two bucket sizes

 	// so much as our high-performance implementation thereof).

-	REQUIREDENTRIES = CACHESIZE / ENTRYSIZE,

-	ENTRIES = REQUIREDENTRIES * TARGETDIVISOR,

+	REQENTRIES = CACHESIZE / ENTRYSIZE,

+	ENTRIES = REQENTRIES * TARGETDIVISOR,

 	BUCKETS = ENTRIES / BUCKETSIZE,

 	// CACHEBITS needs to be computed by hand because no logarithms in

 	// macros. 2^(CACHEBITS) = BUCKETS.

@@ -64,7 +63,6 @@

 	if(data == (void*)-1)

 		sysfatal("failed to allocate cache space of %llux", (usize)ENTRYSIZE*ENTRIES);

 	buckets = sbrk(64 + 64*BUCKETS);

-	freelist = sbrk(sizeof(u32int) * ENTRIES);

 	displacement = ((usize)buckets & 0b111111);

 	if(displacement != 0){

 		displacement = 64 - displacement;

@@ -73,10 +71,7 @@

 	// alignment

 	assert(((usize)buckets&0b111111) == 0);

 	bucketend = buckets + BUCKETS;

-	freelen = ENTRIES / TARGETDIVISOR;

-	for(u32int i = 0; i < freelen; i += 1){

-		freelist[i] = i;

-	}

+	freebufs = REQENTRIES;

 }

 // For now: random eviction.

@@ -110,11 +105,11 @@

 {

 	u32int result;

 	lock(&freelock);

-	if(freelen == 0){

+	if(freebufs == 0){

 		result = evict();

 	} else {

-		freelen -= 1;

-		result = freelist[freelen];

+		result = REQENTRIES - freebufs;

+		freebufs -= 1;

 	}

 	unlock(&freelock);

 	return result;