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| author | Sean Paul <seanpaul@chromium.org> | 2018-02-16 23:47:43 +0300 |
|---|---|---|
| committer | Sean Paul <seanpaul@chromium.org> | 2018-02-16 23:47:43 +0300 |
| commit | d4da404f36b24b089d20db1fb27d8f99cb66f409 (patch) | |
| tree | 349c4b792281826652eb9e6d7a46ed6622dc90de /Documentation/device-mapper/cache.txt | |
| parent | fa4127c5eb8def998fd8a471d51a4f2560dea0a2 (diff) | |
| parent | 933519a5a269d8460450545adefcb5caec622cac (diff) | |
| download | linux-d4da404f36b24b089d20db1fb27d8f99cb66f409.tar.xz | |
Merge airlied/drm-next into drm-misc-next
Backmerge 4.15 and hdcp topic branch
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Diffstat (limited to 'Documentation/device-mapper/cache.txt')
| -rw-r--r-- | Documentation/device-mapper/cache.txt | 9 |
1 files changed, 2 insertions, 7 deletions
diff --git a/Documentation/device-mapper/cache.txt b/Documentation/device-mapper/cache.txt index cdfd0feb294e..ff0841711fd5 100644 --- a/Documentation/device-mapper/cache.txt +++ b/Documentation/device-mapper/cache.txt @@ -59,7 +59,7 @@ Fixed block size The origin is divided up into blocks of a fixed size. This block size is configurable when you first create the cache. Typically we've been using block sizes of 256KB - 1024KB. The block size must be between 64 -(32KB) and 2097152 (1GB) and a multiple of 64 (32KB). +sectors (32KB) and 2097152 sectors (1GB) and a multiple of 64 sectors (32KB). Having a fixed block size simplifies the target a lot. But it is something of a compromise. For instance, a small part of a block may be @@ -119,7 +119,7 @@ doing here to avoid migrating during those peak io moments. For the time being, a message "migration_threshold <#sectors>" can be used to set the maximum number of sectors being migrated, -the default being 204800 sectors (or 100MB). +the default being 2048 sectors (1MB). Updating on-disk metadata ------------------------- @@ -143,11 +143,6 @@ the policy how big this chunk is, but it should be kept small. Like the dirty flags this data is lost if there's a crash so a safe fallback value should always be possible. -For instance, the 'mq' policy, which is currently the default policy, -uses this facility to store the hit count of the cache blocks. If -there's a crash this information will be lost, which means the cache -may be less efficient until those hit counts are regenerated. - Policy hints affect performance, not correctness. Policy messaging |