diff options
| author | Leonid Bloch <lbloch@janustech.com> | 2018-09-26 19:04:44 +0300 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2018-10-01 12:51:12 +0200 |
| commit | 80668d0fb735f0839a46278a7d42116089b82816 (patch) | |
| tree | 5a445e1c51c49d5846829c2c5f8043a3741bd556 /docs/qcow2-cache.txt | |
| parent | b749562d9822d14ef69c9eaa5f85903010b86c30 (diff) | |
qcow2: Increase the default upper limit on the L2 cache size
The upper limit on the L2 cache size is increased from 1 MB to 32 MB
on Linux platforms, and to 8 MB on other platforms (this difference is
caused by the ability to set intervals for cache cleaning on Linux
platforms only).
This is done in order to allow default full coverage with the L2 cache
for images of up to 256 GB in size (was 8 GB). Note, that only the
needed amount to cover the full image is allocated. The value which is
changed here is just the upper limit on the L2 cache size, beyond which
it will not grow, even if the size of the image will require it to.
Signed-off-by: Leonid Bloch <lbloch@janustech.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'docs/qcow2-cache.txt')
| -rw-r--r-- | docs/qcow2-cache.txt | 15 |
1 files changed, 9 insertions, 6 deletions
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. |