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| author | Stephen Rothwell <sfr@canb.auug.org.au> | 2014-01-10 13:05:27 +1100 |
|---|---|---|
| committer | Stephen Rothwell <sfr@canb.auug.org.au> | 2014-01-10 13:05:27 +1100 |
| commit | 76cdadb43fa16b0af6eaf029ec7fdcb81a4d012d (patch) | |
| tree | 9b78d019b04fc697c81933714f9631e606611977 /Documentation | |
| parent | 9fb7add1ea88b6cd87bd72af99c5a2fd4ab849a9 (diff) | |
| parent | 7e664b3dec431eebf0c5df5ff704d6197634cf35 (diff) | |
Merge remote-tracking branch 'device-mapper/for-next'
Conflicts:
drivers/md/dm-thin.c
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/device-mapper/cache-policies.txt | 16 | ||||
| -rw-r--r-- | Documentation/device-mapper/thin-provisioning.txt | 7 |
2 files changed, 21 insertions, 2 deletions
diff --git a/Documentation/device-mapper/cache-policies.txt b/Documentation/device-mapper/cache-policies.txt index df52a849957f..66c2774c0c64 100644 --- a/Documentation/device-mapper/cache-policies.txt +++ b/Documentation/device-mapper/cache-policies.txt @@ -40,8 +40,11 @@ on hit count on entry. The policy aims to take different cache miss costs into account and to adjust to varying load patterns automatically. Message and constructor argument pairs are: - 'sequential_threshold <#nr_sequential_ios>' and - 'random_threshold <#nr_random_ios>'. + 'sequential_threshold <#nr_sequential_ios>' + 'random_threshold <#nr_random_ios>' + 'read_promote_adjustment <value>' + 'write_promote_adjustment <value>' + 'discard_promote_adjustment <value>' The sequential threshold indicates the number of contiguous I/Os required before a stream is treated as sequential. The random threshold @@ -55,6 +58,15 @@ since spindles tend to have good bandwidth. The io_tracker counts contiguous I/Os to try to spot when the io is in one of these sequential modes. +Internally the mq policy maintains a promotion threshold variable. If +the hit count of a block not in the cache goes above this threshold it +gets promoted to the cache. The read, write and discard promote adjustment +tunables allow you to tweak the promotion threshold by adding a small +value based on the io type. They default to 4, 8 and 1 respectively. +If you're trying to quickly warm a new cache device you may wish to +reduce these to encourage promotion. Remember to switch them back to +their defaults after the cache fills though. + cleaner ------- diff --git a/Documentation/device-mapper/thin-provisioning.txt b/Documentation/device-mapper/thin-provisioning.txt index 50c44cf79b0e..8a7a3d46e0da 100644 --- a/Documentation/device-mapper/thin-provisioning.txt +++ b/Documentation/device-mapper/thin-provisioning.txt @@ -235,6 +235,8 @@ i) Constructor read_only: Don't allow any changes to be made to the pool metadata. + error_if_no_space: Error IOs, instead of queueing, if no space. + Data block size must be between 64KB (128 sectors) and 1GB (2097152 sectors) inclusive. @@ -276,6 +278,11 @@ ii) Status contain the string 'Fail'. The userspace recovery tools should then be used. + error_if_no_space|queue_if_no_space + If the pool runs out of data or metadata space, the pool will + either queue or error the IO destined to the data device. The + default is to queue the IO until more space is added. + iii) Messages create_thin <dev id> |