From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [RFC] writeback and cgroup Date: Thu, 5 Apr 2012 09:38:54 -0700 Message-ID: <20120405163854.GE12854@google.com> References: <20120403183655.GA23106@dhcp-172-17-108-109.mtv.corp.google.com> <20120404145134.GC12676@redhat.com> <20120404184909.GB29686@dhcp-172-17-108-109.mtv.corp.google.com> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; bh=1cjqeiAwSjsZD7Ed1MKpCi8Fi9f6PTQPeT8VKwxSv6g=; b=y5TZBXFwxK/sFAU20wCgiq5EVEeqZuM6aRPTsW3j49rIRemySnJP++J8D+EXg2sUp3 GLzLWu7oT/8cxTj2YkCq7biLL1p7nM96vnN68mNs5m/nXsvCOwljtm5ZNkjV5R/EKVFX POJORwthEMlqktChFcbz06u7uyfW551TPFeZ+NSQFi3q2oUfCFTr9bluveqpdloRGB9h sJE/C+W4cAYS7D2Phaq7ESKt63fvxX0wvuU7NmbOho67ZVZncQ6Lu40y6c7CibCD28g9 jf+bdYZiklRk68w7nuRLrLAaRTsfuzX78bHqrWDEJZQkHZt/oH5j2SWrsBMeEy8zqpEh h1hw== Content-Disposition: inline In-Reply-To: <20120404184909.GB29686-RcKxWJ4Cfj1J2suj2OqeGauc2jM2gXBXkQQo+JxHRPFibQn6LdNjmg@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Vivek Goyal Cc: Fengguang Wu , Jan Kara , Jens Axboe , linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, sjayaraman-IBi9RG/b67k@public.gmane.org, andrea-oIIqvOZpAevzfdHfmsDf5w@public.gmane.org, jmoyer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org, lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, ctalbott-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, rni-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, lsf-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Hey, Vivek. On Wed, Apr 04, 2012 at 11:49:09AM -0700, Tejun Heo wrote: > > I am not sure what are you trying to say here. But primarily blk-throttle > > will throttle read and direct IO. Buffered writes will go to root cgroup > > which is typically unthrottled. > > Ooh, my bad then. Anyways, then the same applies to blk-throttle. > Our current implementation essentially collapses at the face of > write-heavy workload. I went through the code and couldn't find where blk-throttle is discriminating async IOs. Were you saying that blk-throttle currently doesn't throttle because those IOs aren't associated with the dirtying task? If so, note that it's different from cfq which explicitly assigns all async IOs when choosing cfqq even if we fix tagging. Thanks. -- tejun