From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753615Ab2LKO1u (ORCPT ); Tue, 11 Dec 2012 09:27:50 -0500 Received: from mail-pa0-f46.google.com ([209.85.220.46]:41274 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753114Ab2LKO1s (ORCPT ); Tue, 11 Dec 2012 09:27:48 -0500 Date: Tue, 11 Dec 2012 06:27:42 -0800 From: Tejun Heo To: Vivek Goyal Cc: Zhao Shuai , axboe@kernel.dk, ctalbott@google.com, rni@google.com, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, containers@lists.linux-foundation.org Subject: Re: performance drop after using blkcg Message-ID: <20121211142742.GE7084@htj.dyndns.org> References: <20121211142518.GA5580@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121211142518.GA5580@redhat.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 Tue, Dec 11, 2012 at 09:25:18AM -0500, Vivek Goyal wrote: > In general, do not use blkcg on faster storage. In current form it > is at best suitable for single rotational SATA/SAS disk. I have not > been able to figure out how to provide fairness without group idling. I think cfq is just the wrong approach for faster non-rotational devices. We should be allocating iops instead of time slices. Thanks. -- tejun