From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vivek Goyal Subject: Re: [PATCH 0/5] IO-less dirty throttling v8 Date: Wed, 10 Aug 2011 14:40:52 -0400 Message-ID: <20110810184052.GE3396@redhat.com> References: <20110806084447.388624428@intel.com> <20110809020127.GA3700@redhat.com> <20110809055551.GP3162@dastard> <20110809140421.GB6482@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Cc: Minchan Kim , Wu Fengguang , Dave Chinner , Christoph Hellwig , LKML , Andrea Righi , Andrew Morton , linux-fsdevel@vger.kernel.org, linux-mm , Jan Kara , KAMEZAWA Hiroyuki To: Greg Thelen Return-path: Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Wed, Aug 10, 2011 at 12:41:00AM -0700, Greg Thelen wrote: [..] > > > However, before we have a "finished product", there is still anothe= r > > > piece of the puzzle to be put in place - memcg-aware buffered > > > writeback. That is, having a flusher thread do work on behalf of > > > memcg in the IO context of the memcg. Then the IO controller just > > > sees a stream of async writes in the context of the memcg the > > > buffered writes came from in the first place. The block layer > > > throttles them just like any other IO in the IO context of the > > > memcg... > > > > Yes that is still a piece remaining. I was hoping that Greg Thelen wi= ll > > be able to extend his patches to submit writes in the context of > > per cgroup flusher/worker threads and solve this problem. > > > > Thanks > > Vivek >=20 > Are you suggesting multiple flushers per bdi (one per cgroup)?=A0 I > thought the point of IO less was to one issue buffered writes from a > single thread. I think in one of the mail threads Dave Chinner mentioned this idea of using per cgroup worker/worqueue. Agreed that it leads back to the issue of multiple writers (but only if multiple cgroups are there). But at the same time it simplifies atleast two problems. - Worker could be migrated to the cgroup we are writting for and we don't need the IO tracking logic. blkio controller should will automatically account the IO to right group. - We don't have to worry about a single flusher thread sleeping on request queue because either queue or group is congested and this can lead other group's IO is not being submitted. Thanks Vivek -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter= .ca/ Don't email: email@kvack.org