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authorJoe Thornber <ejt@redhat.com>2013-12-09 13:53:05 +0100
committerMike Snitzer <snitzer@redhat.com>2014-01-07 16:14:33 +0100
commit78e03d69733c48312ae81fe4ac0790dbea412b9d (patch)
tree47ffaceb2c4c977ab639810d6812a356f364def4 /drivers/md/dm-snap-persistent.c
parentdm cache policy mq: use list_del_init instead of list_del + INIT_LIST_HEAD (diff)
downloadlinux-78e03d69733c48312ae81fe4ac0790dbea412b9d.tar.xz
linux-78e03d69733c48312ae81fe4ac0790dbea412b9d.zip
dm cache policy mq: introduce three promotion threshold tunables
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. This patch introduces three new tunables that allow you to tweak the promotion threshold by adding a small value. These adjustments depend on the io type: read_promote_adjustment: READ io, default 4 write_promote_adjustment: WRITE io, default 8 discard_promote_adjustment: READ/WRITE io to a discarded block, default 1 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. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/dm-snap-persistent.c')
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