From: Tejun Heo Date: Tue, 18 Aug 2015 21:55:18 +0000 (-0700) Subject: blkcg: move root blkg lookup optimization from throtl_lookup_tg() to __blkg_lookup() X-Git-Tag: firefly_0821_release~176^2~1084^2~18 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=85b6bc9db6d5ab6980b43c38b5cbd11d24414ce4;p=firefly-linux-kernel-4.4.55.git blkcg: move root blkg lookup optimization from throtl_lookup_tg() to __blkg_lookup() Currently, both throttle and cfq policies implement their own root blkg (blkcg_gq) lookup fast path. This patch moves root blkg optimization from throtl_lookup_tg() to __blkg_lookup(). cfq-iosched currently doesn't use blkg_lookup() but will be converted and drop the optimization too. Signed-off-by: Tejun Heo Cc: Vivek Goyal Cc: Arianna Avanzini Signed-off-by: Jens Axboe --- diff --git a/block/blk-throttle.c b/block/blk-throttle.c index c2c75477a6b2..1f63fc834dc3 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -452,13 +452,6 @@ static void throtl_pd_reset_stats(struct blkg_policy_data *pd) static struct throtl_grp *throtl_lookup_tg(struct throtl_data *td, struct blkcg *blkcg) { - /* - * This is the common case when there are no blkcgs. Avoid lookup - * in this case - */ - if (blkcg == &blkcg_root) - return td_root_tg(td); - return blkg_to_tg(blkg_lookup(blkcg, td->queue)); } diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h index d5b54aa50582..0609bce69f68 100644 --- a/include/linux/blk-cgroup.h +++ b/include/linux/blk-cgroup.h @@ -249,6 +249,9 @@ static inline struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, { struct blkcg_gq *blkg; + if (blkcg == &blkcg_root) + return q->root_blkg; + blkg = rcu_dereference(blkcg->blkg_hint); if (blkg && blkg->q == q) return blkg;