diff options
| author | Ingo Molnar <mingo@kernel.org> | 2014-03-11 11:53:50 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2014-03-11 11:53:50 +0100 |
| commit | 0066f3b93e144762b409940fa37bb1cd36c1baf7 (patch) | |
| tree | 0c99b2754fb16c2a787bc1d086bd6fb268b12b1a /Documentation/device-mapper/cache.txt | |
| parent | e65312fe868da53077780de618e213a53dc90d00 (diff) | |
| parent | b8ad0f912b93c23c34dfedc615a0eeba6ca29463 (diff) | |
Merge branch 'perf/urgent' into perf/core
Merge the latest fixes.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'Documentation/device-mapper/cache.txt')
| -rw-r--r-- | Documentation/device-mapper/cache.txt | 11 |
1 files changed, 5 insertions, 6 deletions
diff --git a/Documentation/device-mapper/cache.txt b/Documentation/device-mapper/cache.txt index e6b72d355151..68c0f517c60e 100644 --- a/Documentation/device-mapper/cache.txt +++ b/Documentation/device-mapper/cache.txt @@ -124,12 +124,11 @@ the default being 204800 sectors (or 100MB). Updating on-disk metadata ------------------------- -On-disk metadata is committed every time a REQ_SYNC or REQ_FUA bio is -written. If no such requests are made then commits will occur every -second. This means the cache behaves like a physical disk that has a -write cache (the same is true of the thin-provisioning target). If -power is lost you may lose some recent writes. The metadata should -always be consistent in spite of any crash. +On-disk metadata is committed every time a FLUSH or FUA bio is written. +If no such requests are made then commits will occur every second. This +means the cache behaves like a physical disk that has a volatile write +cache. If power is lost you may lose some recent writes. The metadata +should always be consistent in spite of any crash. The 'dirty' state for a cache block changes far too frequently for us to keep updating it on the fly. So we treat it as a hint. In normal |