From: Vivek Goyal Subject: Re: [PATCH 2/6] blkcg: add blkg_[rw]stat->aux_cnt and replace cfq_group->dead_stats with it Date: Fri, 26 Jun 2015 09:45:25 -0400 Message-ID: <20150626134525.GB14803@redhat.com> References: <1435268337-1738-1-git-send-email-tj@kernel.org> <1435268337-1738-3-git-send-email-tj@kernel.org> <20150626132702.GA14803@redhat.com> <20150626133540.GA15805@mtj.duckdns.org> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <20150626133540.GA15805-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Tejun Heo Cc: axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, avanzini.arianna-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, kernel-team-b10kYP2dOMg@public.gmane.org On Fri, Jun 26, 2015 at 09:35:40AM -0400, Tejun Heo wrote: > On Fri, Jun 26, 2015 at 09:27:02AM -0400, Vivek Goyal wrote: > > On Thu, Jun 25, 2015 at 05:38:53PM -0400, Tejun Heo wrote: > > > > [..] > > > It's planned that the core stats will be moved to blkcg_gq, so we want > > > to move the mechanism for keeping track of the stats of dead children > > > from cfq to blkcg core. This patch adds blkg_[rw]stat->aux_cnt which > > > are atomic64_t's keeping track of auxiliary counts which are excluded > > > when reading local counts but included for recursive. > > > > Hi Tejun, > > > > So aux_cnt is atomic64_t as updation is not the hot path hence there is > > not much value in keeping it as per cpu? > > I'm not following. aux_cnt isn't per-cpu. I was just curious that why aux_cnt is different from rest of the stats. (It is atomic64_t while others are not). Thanks Vivek