Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754217Ab0GXJHM (ORCPT ); Sat, 24 Jul 2010 05:07:12 -0400 Received: from mail-ww0-f44.google.com ([74.125.82.44]:46838 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753685Ab0GXJHJ convert rfc822-to-8bit (ORCPT ); Sat, 24 Jul 2010 05:07:09 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=hhvBr+BVLxvoRmrFhDHjvLbHDW3lhV91Vx9DLcmnXzI7ljJo9+jlAcaccM1iZ1mMTs hOFvYWE/z/yvSqUZE354joD/h97vCTr21XsHD7wBuX6T8gTTt3dcsGdOVY/XrBLFNQkw 0ou2b9+ICR7KCI+UfWeuFt81NW+SHolbu6q9E= MIME-Version: 1.0 In-Reply-To: <20100724085135.GB32006@infradead.org> References: <1279739181-24482-1-git-send-email-vgoyal@redhat.com> <20100722055602.GA18566@infradead.org> <20100722140044.GA28684@redhat.com> <20100724085135.GB32006@infradead.org> Date: Sat, 24 Jul 2010 11:07:07 +0200 Message-ID: Subject: Re: [RFC PATCH] cfq-iosced: Implement IOPS mode and group_idle tunable V3 From: Corrado Zoccolo To: Christoph Hellwig Cc: Vivek Goyal , linux-kernel@vger.kernel.org, axboe@kernel.dk, nauman@google.com, dpshah@google.com, guijianfeng@cn.fujitsu.com, jmoyer@redhat.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1964 Lines: 39 On Sat, Jul 24, 2010 at 10:51 AM, Christoph Hellwig wrote: > To me this sounds like slice_idle=0 is the right default then, as it > gives useful behaviour for all systems linux runs on. No, it will give bad performance on single disks, possibly worse than deadline (deadline at least sorts the requests between different queues, while CFQ with slice_idle=0 doesn't even do this for readers). Setting slice_idle to 0 should be considered only when a single sequential reader cannot saturate the disk bandwidth, and this happens only on smart enough hardware with large number of spindles. >  Setups with > more than a few spindles are for sure more common than setups making > use of cgroups.  Especially given that cgroups are more of a high end > feature you'd rarely use on a single SATA spindle anyway.  So setting > a paramter to make this useful sounds like the much better option. > > Especially given that the block cgroup code doesn't work particularly > well in presence of barriers, which are on for any kind of real life > production setup anyway. > > -- __________________________________________________________________________ dott. Corrado Zoccolo                          mailto:czoccolo@gmail.com PhD - Department of Computer Science - University of Pisa, Italy -------------------------------------------------------------------------- The self-confidence of a warrior is not the self-confidence of the average man. The average man seeks certainty in the eyes of the onlooker and calls that self-confidence. The warrior seeks impeccability in his own eyes and calls that humbleness.                                Tales of Power - C. Castaneda -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/