diff options
Diffstat (limited to 'block/qcow2.c')
| -rw-r--r-- | block/qcow2.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/block/qcow2.c b/block/qcow2.c index 7fb2730f09..48d22f48d5 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -788,6 +788,7 @@ static void read_cache_sizes(BlockDriverState *bs, QemuOpts *opts, BDRVQcow2State *s = bs->opaque; uint64_t combined_cache_size, l2_cache_max_setting; bool l2_cache_size_set, refcount_cache_size_set, combined_cache_size_set; + bool l2_cache_entry_size_set; int min_refcount_cache = MIN_REFCOUNT_CACHE_SIZE * s->cluster_size; uint64_t virtual_disk_size = bs->total_sectors * BDRV_SECTOR_SIZE; uint64_t max_l2_cache = virtual_disk_size / (s->cluster_size / 8); @@ -795,6 +796,7 @@ static void read_cache_sizes(BlockDriverState *bs, QemuOpts *opts, combined_cache_size_set = qemu_opt_get(opts, QCOW2_OPT_CACHE_SIZE); l2_cache_size_set = qemu_opt_get(opts, QCOW2_OPT_L2_CACHE_SIZE); refcount_cache_size_set = qemu_opt_get(opts, QCOW2_OPT_REFCOUNT_CACHE_SIZE); + l2_cache_entry_size_set = qemu_opt_get(opts, QCOW2_OPT_L2_CACHE_ENTRY_SIZE); combined_cache_size = qemu_opt_get_size(opts, QCOW2_OPT_CACHE_SIZE, 0); l2_cache_max_setting = qemu_opt_get_size(opts, QCOW2_OPT_L2_CACHE_SIZE, @@ -841,6 +843,16 @@ static void read_cache_sizes(BlockDriverState *bs, QemuOpts *opts, } } } + + /* + * If the L2 cache is not enough to cover the whole disk then + * default to 4KB entries. Smaller entries reduce the cost of + * loads and evictions and increase I/O performance. + */ + if (*l2_cache_size < max_l2_cache && !l2_cache_entry_size_set) { + *l2_cache_entry_size = MIN(s->cluster_size, 4096); + } + /* l2_cache_size and refcount_cache_size are ensured to have at least * their minimum values in qcow2_update_options_prepare() */ |