diff options
| -rw-r--r-- | block/qcow2.c | 21 | ||||
| -rw-r--r-- | block/qcow2.h | 4 | ||||
| -rw-r--r-- | docs/qcow2-cache.txt | 15 | ||||
| -rw-r--r-- | qemu-options.hx | 6 | ||||
| -rwxr-xr-x | tests/qemu-iotests/137 | 8 | ||||
| -rw-r--r-- | tests/qemu-iotests/137.out | 4 |
6 files changed, 33 insertions, 25 deletions
diff --git a/block/qcow2.c b/block/qcow2.c index cd0053b6ee..589f6c1b1c 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -777,29 +777,35 @@ static void read_cache_sizes(BlockDriverState *bs, QemuOpts *opts, uint64_t *refcount_cache_size, Error **errp) { BDRVQcow2State *s = bs->opaque; - uint64_t combined_cache_size; + uint64_t combined_cache_size, l2_cache_max_setting; bool l2_cache_size_set, refcount_cache_size_set, combined_cache_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); 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); combined_cache_size = qemu_opt_get_size(opts, QCOW2_OPT_CACHE_SIZE, 0); - *l2_cache_size = qemu_opt_get_size(opts, QCOW2_OPT_L2_CACHE_SIZE, 0); + l2_cache_max_setting = qemu_opt_get_size(opts, QCOW2_OPT_L2_CACHE_SIZE, + DEFAULT_L2_CACHE_MAX_SIZE); *refcount_cache_size = qemu_opt_get_size(opts, QCOW2_OPT_REFCOUNT_CACHE_SIZE, 0); *l2_cache_entry_size = qemu_opt_get_size( opts, QCOW2_OPT_L2_CACHE_ENTRY_SIZE, s->cluster_size); + *l2_cache_size = MIN(max_l2_cache, l2_cache_max_setting); + if (combined_cache_size_set) { if (l2_cache_size_set && refcount_cache_size_set) { error_setg(errp, QCOW2_OPT_CACHE_SIZE ", " QCOW2_OPT_L2_CACHE_SIZE " and " QCOW2_OPT_REFCOUNT_CACHE_SIZE " may not be set " "at the same time"); return; - } else if (*l2_cache_size > combined_cache_size) { + } else if (l2_cache_size_set && + (l2_cache_max_setting > combined_cache_size)) { error_setg(errp, QCOW2_OPT_L2_CACHE_SIZE " may not exceed " QCOW2_OPT_CACHE_SIZE); return; @@ -814,9 +820,6 @@ static void read_cache_sizes(BlockDriverState *bs, QemuOpts *opts, } else if (refcount_cache_size_set) { *l2_cache_size = combined_cache_size - *refcount_cache_size; } else { - uint64_t virtual_disk_size = bs->total_sectors * BDRV_SECTOR_SIZE; - uint64_t max_l2_cache = virtual_disk_size / (s->cluster_size / 8); - /* Assign as much memory as possible to the L2 cache, and * use the remainder for the refcount cache */ if (combined_cache_size >= max_l2_cache + min_refcount_cache) { @@ -828,12 +831,6 @@ static void read_cache_sizes(BlockDriverState *bs, QemuOpts *opts, *l2_cache_size = combined_cache_size - *refcount_cache_size; } } - } else { - if (!l2_cache_size_set) { - *l2_cache_size = MAX(DEFAULT_L2_CACHE_SIZE, - (uint64_t)DEFAULT_L2_CACHE_CLUSTERS - * s->cluster_size); - } } /* l2_cache_size and refcount_cache_size are ensured to have at least * their minimum values in qcow2_update_options_prepare() */ diff --git a/block/qcow2.h b/block/qcow2.h index a8d6f757b1..2f8c1fd15c 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -74,9 +74,7 @@ /* 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_SIZE S_1MiB +#define DEFAULT_L2_CACHE_MAX_SIZE S_1MiB #define DEFAULT_CLUSTER_SIZE S_64KiB diff --git a/docs/qcow2-cache.txt b/docs/qcow2-cache.txt index 7e28b41bd3..750447ea4f 100644 --- a/docs/qcow2-cache.txt +++ b/docs/qcow2-cache.txt @@ -125,8 +125,12 @@ There are a few things that need to be taken into account: - Both caches must have a size that is a multiple of the cluster size (or the cache entry size: see "Using smaller cache sizes" below). - - The default L2 cache size is 8 clusters or 1MB (whichever is more), - and the minimum is 2 clusters (or 2 cache entries, see below). + - The maximum L2 cache size is 1 MB by default (enough for full coverage + of 8 GB images, with the default cluster size). This value can be + modified using the "l2-cache-size" option. QEMU will not use more memory + than needed to hold all of the image's L2 tables, regardless of this max. + value. The minimal L2 cache size is 2 clusters (or 2 cache entries, see + below). - The default (and minimum) refcount cache size is 4 clusters. @@ -184,9 +188,10 @@ Some things to take into account: always uses the cluster size as the entry size. - If the L2 cache is big enough to hold all of the image's L2 tables - (as explained in the "Choosing the right cache sizes" section - earlier in this document) then none of this is necessary and you - can omit the "l2-cache-entry-size" parameter altogether. + (as explained in the "Choosing the right cache sizes" and "How to + configure the cache sizes" sections in this document) then none of + this is necessary and you can omit the "l2-cache-entry-size" + parameter altogether. Reducing the memory usage diff --git a/qemu-options.hx b/qemu-options.hx index 2db6247eff..6eef0f5651 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -736,9 +736,9 @@ The maximum total size of the L2 table and refcount block caches in bytes @item l2-cache-size The maximum size of the L2 table cache in bytes -(default: if cache-size is not defined - 1048576 bytes or 8 clusters, whichever -is larger; otherwise, as large as possible or needed within the cache-size, -while permitting the requested or the minimal refcount cache size) +(default: if cache-size is not specified - 1M; otherwise, as large as possible +within the cache-size, while permitting the requested or the minimal refcount +cache size) @item refcount-cache-size The maximum size of the refcount block cache in bytes diff --git a/tests/qemu-iotests/137 b/tests/qemu-iotests/137 index 87965625d8..19e8597306 100755 --- a/tests/qemu-iotests/137 +++ b/tests/qemu-iotests/137 @@ -109,7 +109,6 @@ $QEMU_IO \ -c "reopen -o cache-size=1M,l2-cache-size=64k,refcount-cache-size=64k" \ -c "reopen -o cache-size=1M,l2-cache-size=2M" \ -c "reopen -o cache-size=1M,refcount-cache-size=2M" \ - -c "reopen -o l2-cache-size=256T" \ -c "reopen -o l2-cache-entry-size=33k" \ -c "reopen -o l2-cache-entry-size=128k" \ -c "reopen -o refcount-cache-size=256T" \ @@ -119,6 +118,13 @@ $QEMU_IO \ -c "reopen -o cache-clean-interval=-1" \ "$TEST_IMG" | _filter_qemu_io +IMGOPTS="cluster_size=256k" _make_test_img 32P +$QEMU_IO \ + -c "reopen -o l2-cache-entry-size=512,l2-cache-size=1T" \ + "$TEST_IMG" | _filter_qemu_io + +_make_test_img 64M + echo echo === Test transaction semantics === echo diff --git a/tests/qemu-iotests/137.out b/tests/qemu-iotests/137.out index 6a2ffc71fd..2c080b72f3 100644 --- a/tests/qemu-iotests/137.out +++ b/tests/qemu-iotests/137.out @@ -19,7 +19,6 @@ Parameter 'lazy-refcounts' expects 'on' or 'off' cache-size, l2-cache-size and refcount-cache-size may not be set at the same time l2-cache-size may not exceed cache-size refcount-cache-size may not exceed cache-size -L2 cache size too big L2 cache entry size must be a power of two between 512 and the cluster size (65536) L2 cache entry size must be a power of two between 512 and the cluster size (65536) Refcount cache size too big @@ -27,6 +26,9 @@ Conflicting values for qcow2 options 'overlap-check' ('constant') and 'overlap-c Unsupported value 'blubb' for qcow2 option 'overlap-check'. Allowed are any of the following: none, constant, cached, all Unsupported value 'blubb' for qcow2 option 'overlap-check'. Allowed are any of the following: none, constant, cached, all Cache clean interval too big +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=36028797018963968 +L2 cache size too big +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 === Test transaction semantics === |