diff options
| -rw-r--r-- | block/qcow2-cache.c | 33 |
1 files changed, 15 insertions, 18 deletions
diff --git a/block/qcow2-cache.c b/block/qcow2-cache.c index 6e78c8ffba..3a318955e6 100644 --- a/block/qcow2-cache.c +++ b/block/qcow2-cache.c @@ -28,10 +28,10 @@ #include "trace.h" typedef struct Qcow2CachedTable { - int64_t offset; - bool dirty; - int cache_hits; - int ref; + int64_t offset; + bool dirty; + uint64_t lru_counter; + int ref; } Qcow2CachedTable; struct Qcow2Cache { @@ -40,6 +40,7 @@ struct Qcow2Cache { int size; bool depends_on_flush; void *table_array; + uint64_t lru_counter; }; static inline void *qcow2_cache_get_table_addr(BlockDriverState *bs, @@ -233,16 +234,18 @@ int qcow2_cache_empty(BlockDriverState *bs, Qcow2Cache *c) for (i = 0; i < c->size; i++) { assert(c->entries[i].ref == 0); c->entries[i].offset = 0; - c->entries[i].cache_hits = 0; + c->entries[i].lru_counter = 0; } + c->lru_counter = 0; + return 0; } static int qcow2_cache_find_entry_to_replace(Qcow2Cache *c) { int i; - int min_count = INT_MAX; + uint64_t min_lru_counter = UINT64_MAX; int min_index = -1; @@ -251,15 +254,9 @@ static int qcow2_cache_find_entry_to_replace(Qcow2Cache *c) continue; } - if (c->entries[i].cache_hits < min_count) { + if (c->entries[i].lru_counter < min_lru_counter) { min_index = i; - min_count = c->entries[i].cache_hits; - } - - /* Give newer hits priority */ - /* TODO Check how to optimize the replacement strategy */ - if (c->entries[i].cache_hits > 1) { - c->entries[i].cache_hits /= 2; + min_lru_counter = c->entries[i].lru_counter; } } @@ -316,14 +313,10 @@ static int qcow2_cache_do_get(BlockDriverState *bs, Qcow2Cache *c, } } - /* Give the table some hits for the start so that it won't be replaced - * immediately. The number 32 is completely arbitrary. */ - c->entries[i].cache_hits = 32; c->entries[i].offset = offset; /* And return the right table */ found: - c->entries[i].cache_hits++; c->entries[i].ref++; *table = qcow2_cache_get_table_addr(bs, c, i); @@ -356,6 +349,10 @@ int qcow2_cache_put(BlockDriverState *bs, Qcow2Cache *c, void **table) c->entries[i].ref--; *table = NULL; + if (c->entries[i].ref == 0) { + c->entries[i].lru_counter = ++c->lru_counter; + } + assert(c->entries[i].ref >= 0); return 0; } |