From: Tejun Heo Date: Thu, 19 Apr 2012 23:29:24 +0000 (-0700) Subject: blkcg: use radix tree to index blkgs from blkcg X-Git-Tag: v3.5-rc1~42^2~3 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a637120e49021d197e9578cba545bbaa459cbb51;p=pandora-kernel.git blkcg: use radix tree to index blkgs from blkcg blkg lookup is currently performed by traversing linked list anchored at blkcg->blkg_list. This is very unscalable and with blk-throttle enabled and enough request queues on the system, this can get very ugly quickly (blk-throttle performs look up on every bio submission). This patch makes blkcg use radix tree to index blkgs combined with simple last-looked-up hint. This is mostly identical to how icqs are indexed from ioc. Note that because __blkg_lookup() may be invoked without holding queue lock, hint is only updated from __blkg_lookup_create(). Due to cfq's cfqq caching, this makes hint updates overly lazy. This will be improved with scheduled blkcg aware request allocation. Signed-off-by: Tejun Heo Cc: Vivek Goyal Signed-off-by: Jens Axboe --- Reading git-diff-tree failed