diff options
| -rw-r--r-- | block/qcow2.h | 6 | ||||
| -rw-r--r-- | docs/qcow2-cache.txt | 15 | ||||
| -rw-r--r-- | qemu-options.hx | 6 |
3 files changed, 17 insertions, 10 deletions
diff --git a/block/qcow2.h b/block/qcow2.h index 2f8c1fd15c..0f0e3534bf 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -74,7 +74,11 @@ /* Must be at least 4 to cover all cases of refcount table growth */ #define MIN_REFCOUNT_CACHE_SIZE 4 /* clusters */ -#define DEFAULT_L2_CACHE_MAX_SIZE S_1MiB +#ifdef CONFIG_LINUX +#define DEFAULT_L2_CACHE_MAX_SIZE S_32MiB +#else +#define DEFAULT_L2_CACHE_MAX_SIZE S_8MiB +#endif #define DEFAULT_CLUSTER_SIZE S_64KiB diff --git a/docs/qcow2-cache.txt b/docs/qcow2-cache.txt index 750447ea4f..1fcc0658b2 100644 --- a/docs/qcow2-cache.txt +++ b/docs/qcow2-cache.txt @@ -125,12 +125,15 @@ 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 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 maximum L2 cache size is 32 MB by default on Linux platforms (enough + for full coverage of 256 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. + On non-Linux platforms the maximal value is smaller by default (8 MB) and + this difference stems from the fact that on Linux the cache can be cleared + periodically if needed, using the "cache-clean-interval" option (see below). + The minimal L2 cache size is 2 clusters (or 2 cache entries, see below). - The default (and minimum) refcount cache size is 4 clusters. diff --git a/qemu-options.hx b/qemu-options.hx index 6eef0f5651..14aee78c6c 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 specified - 1M; otherwise, as large as possible -within the cache-size, while permitting the requested or the minimal refcount -cache size) +(default: if cache-size is not specified - 32M on Linux platforms, and 8M on +non-Linux platforms; 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 |