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Date: Fri, 20 Apr 2012 13:26:39 -0400 From: Vivek Goyal <vgoyal@...hat.com> To: Tejun Heo <tj@...nel.org> Cc: axboe@...nel.dk, ctalbott@...gle.com, rni@...gle.com, cgroups@...r.kernel.org, containers@...ts.linux-foundation.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH 4/4] blkcg: use radix tree to index blkgs from blkcg On Thu, Apr 19, 2012 at 04:29:24PM -0700, Tejun Heo wrote: > 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 <tj@...nel.org> > Cc: Vivek Goyal <vgoyal@...hat.com> Nice to see radix tree lookup and caching hint. Helps with scalability. Acked-by: Vivek Goyal <vgoyal@...hat.com> Vivek -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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