Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753734Ab0GITp1 (ORCPT ); Fri, 9 Jul 2010 15:45:27 -0400 Received: from mail-wy0-f174.google.com ([74.125.82.174]:41185 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753063Ab0GITpZ convert rfc822-to-8bit (ORCPT ); Fri, 9 Jul 2010 15:45:25 -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=WpAKyDJow6Nq/88SPKGIqvmvK3EpQz/NRSngplBAFUedP76l61Wha86J/jrOqzgqxW t1GJ9o3uMy0wZn5FMsv+cvwGHZqhNossa4nDfyimZEhVAj53X7trpQs55U4pcxryq6DR lx1S4k3UC49Oe9P1y0pPgc1JWHidzyeMfBFZU= MIME-Version: 1.0 In-Reply-To: References: Date: Fri, 9 Jul 2010 21:45:22 +0200 Message-ID: Subject: Re: [PATCH 0/2] cfq-iosched: fixing RQ_NOIDLE handling. From: Corrado Zoccolo To: Jeff Moyer Cc: Jens Axboe , Linux-Kernel , Vivek Goyal 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: 4099 Lines: 91 On Fri, Jul 9, 2010 at 4:07 PM, Jeff Moyer wrote: > Corrado Zoccolo writes: > >> On Wed, Jul 7, 2010 at 10:06 PM, Jeff Moyer wrote: >>> Corrado Zoccolo writes: >>> >>>> On Wed, Jul 7, 2010 at 7:03 PM, Jeff Moyer wrote: >>>>> Corrado Zoccolo writes: >>>>> >>>>>> Hi Jens, >>>>>> patch 8e55063 "cfq-iosched: fix corner cases in idling logic", is >>>>>> suspected for some regressions on high end hardware. >>>>>> The two patches from this series: >>>>>> - [PATCH 1/2] cfq-iosched: fix tree-wide handling of rq_noidle >>>>>> - [PATCH 2/2] cfq-iosched: RQ_NOIDLE enabled for SYNC_WORKLOAD >>>>>> fix two issues that I have identified, related to how RQ_NOIDLE is >>>>>> used by the upper layers. >>>>>> First patch makes sure that a RQ_NOIDLE coming after a sequence of >>>>>> possibly idling requests from the same queue on the no-idle tree will >>>>>> clear the noidle_tree_requires_idle flag. >>>>>> Second patch enables RQ_NOIDLE for queues in the idling tree, >>>>>> restoring the behaviour pre-8e55063 patch. >>>>> >>>>> Hi, Corrado, >>>>> >>>>> I ran your kernel through my tests.  Here are the results, up against >>>>> vanilla, deadline, and the blk_yield patch set: >>>>> >>>> Hi Jeff, >>>> can you also add cfq with 8e55063 reverted to the testing mix? >>> >>> Sure, the results now look like this: >>> >>>                 just    just >>>                fs_mark  fio        mixed >>> -------------------------------+-------------- >>> deadline        529.44   151.4 | 450.0    78.2 >>> vanilla cfq     107.88   164.4 |   6.6   137.2 >>> blk_yield cfq   530.82   158.7 | 113.2    78.6 >>> corrado cfq     110.16   220.6 |   7.0   159.8 >>> 8e55063 revert  559.66   198.9 |  16.1   153.3 >>> >>> I had accidentally run your patch set (corrado cfq) on ext3, so the >>> numbers were a bit off (everything else was run against ext4).  The >>> corrected numbers above reflect the performance on ext4, which is much >>> better for the sequential reader, but still not great for the fs_mark >>> run.  Reverting 8e55063 definitely gets us into better shape.  However, >>> if we care about the mixed workload, then it won't be enough. >> >> Wondering why deadline performs so well in the fs_mark workload. Is it >> because it doesn't distinguish between sync and async writes? > > It performs well because it doesn't do any idling. > >> Maybe we can achieve something similar by putting all sync writes >> (that are marked as REQ_NOIDLE) in the noidle tree? This, coupled with >> making jbd(2) perform sync writes, should make the yield automatic, >> since they all live in the same tree for which we don't idle between >> queues, and should be able to provide fairness compared to a >> sequential reader (that lives in the other tree). >> >> Can you test the attached patch, where I also added your changes to >> make jbd(2) to perform sync writes? > > I'm not sure what kernel you generated that patch against.  I'm working > with 2.6.35-rc3 or later, and your patch does not apply there. It's Jens' block/for-2.6.36 tree. > > Cheers, > Jeff > -- __________________________________________________________________________ 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/