From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752205Ab2DVOcT (ORCPT ); Sun, 22 Apr 2012 10:32:19 -0400 Received: from mga11.intel.com ([192.55.52.93]:44494 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751504Ab2DVOcQ (ORCPT ); Sun, 22 Apr 2012 10:32:16 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.71,315,1320652800"; d="scan'208";a="144581809" Date: Sun, 22 Apr 2012 22:26:48 +0800 From: Fengguang Wu To: Tejun Heo Cc: Vivek Goyal , Jan Kara , Jens Axboe , linux-mm@kvack.org, sjayaraman@suse.com, andrea@betterlinux.com, jmoyer@redhat.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, kamezawa.hiroyu@jp.fujitsu.com, lizefan@huawei.com, containers@lists.linux-foundation.org, cgroups@vger.kernel.org, ctalbott@google.com, rni@google.com, lsf@lists.linux-foundation.org Subject: Re: [RFC] writeback and cgroup Message-ID: <20120422142648.GA9530@localhost> References: <20120403183655.GA23106@dhcp-172-17-108-109.mtv.corp.google.com> <20120404175124.GA8931@localhost> <20120404193355.GD29686@dhcp-172-17-108-109.mtv.corp.google.com> <20120406095934.GA10465@localhost> <20120417223854.GG19975@google.com> <20120419142343.GA12684@localhost> <20120419183118.GM10216@redhat.com> <20120420124518.GA7133@localhost> <20120420192930.GR22419@redhat.com> <20120420213301.GA29134@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120420213301.GA29134@google.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 20, 2012 at 02:33:01PM -0700, Tejun Heo wrote: > On Fri, Apr 20, 2012 at 03:29:30PM -0400, Vivek Goyal wrote: > > I am personally is not too excited about the case of putting async IO > > in separate groups due to the reason that async IO of one group will > > start impacting latencies of sync IO of another group and in practice > > it might not be desirable. But there are others who have use cases for > > separate async IO queue. So as long as switch is there to change the > > behavior, I am not too worried. > > Why not just fix cfq so that it prefers groups w/ sync IOs? There may be a sync+async group in front, but when switch into it, it decides to give its async queue a run. That's not necessarily a bad decision, but we do lose some control here. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fengguang Wu Subject: Re: [RFC] writeback and cgroup Date: Sun, 22 Apr 2012 22:26:48 +0800 Message-ID: <20120422142648.GA9530@localhost> References: <20120403183655.GA23106@dhcp-172-17-108-109.mtv.corp.google.com> <20120404175124.GA8931@localhost> <20120404193355.GD29686@dhcp-172-17-108-109.mtv.corp.google.com> <20120406095934.GA10465@localhost> <20120417223854.GG19975@google.com> <20120419142343.GA12684@localhost> <20120419183118.GM10216@redhat.com> <20120420124518.GA7133@localhost> <20120420192930.GR22419@redhat.com> <20120420213301.GA29134@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Vivek Goyal , Jan Kara , Jens Axboe , linux-mm@kvack.org, sjayaraman@suse.com, andrea@betterlinux.com, jmoyer@redhat.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, kamezawa.hiroyu@jp.fujitsu.com, lizefan@huawei.com, containers@lists.linux-foundation.org, cgroups@vger.kernel.org, ctalbott@google.com, rni@google.com, lsf@lists.linux-foundation.org To: Tejun Heo Return-path: Content-Disposition: inline In-Reply-To: <20120420213301.GA29134@google.com> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Fri, Apr 20, 2012 at 02:33:01PM -0700, Tejun Heo wrote: > On Fri, Apr 20, 2012 at 03:29:30PM -0400, Vivek Goyal wrote: > > I am personally is not too excited about the case of putting async IO > > in separate groups due to the reason that async IO of one group will > > start impacting latencies of sync IO of another group and in practice > > it might not be desirable. But there are others who have use cases for > > separate async IO queue. So as long as switch is there to change the > > behavior, I am not too worried. > > Why not just fix cfq so that it prefers groups w/ sync IOs? There may be a sync+async group in front, but when switch into it, it decides to give its async queue a run. That's not necessarily a bad decision, but we do lose some control here. -- 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