From bc85ef265a0118d044ff62ae217c186cb08e0866 Mon Sep 17 00:00:00 2001 From: Max Reitz Date: Mon, 1 Jun 2015 18:09:19 +0200 Subject: [PATCH] qcow2: Add DEFAULT_L2_CACHE_CLUSTERS If a relatively large cluster size is chosen, the default of 1 MB L2 cache is not really appropriate. In this case, unless overridden by the user, the default cache size should not be determined by its size in bytes but by the number of L2 tables (clusters) it is supposed to contain. Note that without this patch, MIN_L2_CACHE_SIZE will effectively take over the same role. However, providing space for just two L2 tables is not enough to be the default. Signed-off-by: Max Reitz Reviewed-by: Alberto Garcia Signed-off-by: Kevin Wolf --- block/qcow2.c | 11 ++++++++--- block/qcow2.h | 2 ++ 2 files changed, 10 insertions(+), 3 deletions(-) diff --git a/block/qcow2.c b/block/qcow2.c index f7b4cc6a32..c4f6938a36 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -483,9 +483,11 @@ static const char *overlap_bool_option_names[QCOW2_OL_MAX_BITNR] = { [QCOW2_OL_INACTIVE_L2_BITNR] = QCOW2_OPT_OVERLAP_INACTIVE_L2, }; -static void read_cache_sizes(QemuOpts *opts, uint64_t *l2_cache_size, +static void read_cache_sizes(BlockDriverState *bs, QemuOpts *opts, + uint64_t *l2_cache_size, uint64_t *refcount_cache_size, Error **errp) { + BDRVQcowState *s = bs->opaque; uint64_t combined_cache_size; bool l2_cache_size_set, refcount_cache_size_set, combined_cache_size_set; @@ -525,7 +527,9 @@ static void read_cache_sizes(QemuOpts *opts, uint64_t *l2_cache_size, } } else { if (!l2_cache_size_set && !refcount_cache_size_set) { - *l2_cache_size = DEFAULT_L2_CACHE_BYTE_SIZE; + *l2_cache_size = MAX(DEFAULT_L2_CACHE_BYTE_SIZE, + (uint64_t)DEFAULT_L2_CACHE_CLUSTERS + * s->cluster_size); *refcount_cache_size = *l2_cache_size / DEFAULT_L2_REFCOUNT_SIZE_RATIO; } else if (!l2_cache_size_set) { @@ -803,7 +807,8 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags, goto fail; } - read_cache_sizes(opts, &l2_cache_size, &refcount_cache_size, &local_err); + read_cache_sizes(bs, opts, &l2_cache_size, &refcount_cache_size, + &local_err); if (local_err) { error_propagate(errp, local_err); ret = -EINVAL; diff --git a/block/qcow2.h b/block/qcow2.h index aa200223ce..5936d299a3 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -68,6 +68,8 @@ /* Must be at least 4 to cover all cases of refcount table growth */ #define MIN_REFCOUNT_CACHE_SIZE 4 /* clusters */ +/* Whichever is more */ +#define DEFAULT_L2_CACHE_CLUSTERS 8 /* clusters */ #define DEFAULT_L2_CACHE_BYTE_SIZE 1048576 /* bytes */ /* The refblock cache needs only a fourth of the L2 cache size to cover as many