From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <1504199166.666.11.camel@gmx.de> Subject: Re: [PATCH BUGFIX/IMPROVEMENT V2 0/3] three bfq fixes restoring service guarantees with random sync writes in bg From: Mike Galbraith To: Mel Gorman , Paolo Valente Cc: Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, ulf.hansson@linaro.org, broonie@kernel.org, lee.tibbert@gmail.com, oleksandr@natalenko.name Date: Thu, 31 Aug 2017 19:06:06 +0200 In-Reply-To: <20170831144257.oa5nm6vzihpam6kw@techsingularity.net> References: <20170831064631.2223-1-paolo.valente@linaro.org> <20170831144257.oa5nm6vzihpam6kw@techsingularity.net> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 List-ID: On Thu, 2017-08-31 at 15:42 +0100, Mel Gorman wrote: > On Thu, Aug 31, 2017 at 08:46:28AM +0200, Paolo Valente wrote: > > [SECOND TAKE, with just the name of one of the tester fixed] > >=20 > > Hi, > > while testing the read-write unfairness issues reported by Mel, I > > found BFQ failing to guarantee good responsiveness against heavy > > random sync writes in the background, i.e., multiple writers doing > > random writes and systematic fdatasync [1]. The failure was caused by > > three related bugs, because of which BFQ failed to guarantee to > > high-weight processes the expected fraction of the throughput. > >=20 >=20 > Queued on top of Ming's most recent series even though that's still a wor= k > in progress. I should know in a few days how things stand. It seems to have cured an interactivity issue I regularly meet during kbuild final link/depmod phase of fat kernel kbuild, especially bad with evolution mail usage during that on spinning rust. =C2=A0Can't really say for sure given this is not based on measurement. -Mike=C2=A0 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751979AbdHaRG2 convert rfc822-to-8bit (ORCPT ); Thu, 31 Aug 2017 13:06:28 -0400 Received: from mout.gmx.net ([212.227.15.19]:65521 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750955AbdHaRG0 (ORCPT ); Thu, 31 Aug 2017 13:06:26 -0400 Message-ID: <1504199166.666.11.camel@gmx.de> Subject: Re: [PATCH BUGFIX/IMPROVEMENT V2 0/3] three bfq fixes restoring service guarantees with random sync writes in bg From: Mike Galbraith To: Mel Gorman , Paolo Valente Cc: Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, ulf.hansson@linaro.org, broonie@kernel.org, lee.tibbert@gmail.com, oleksandr@natalenko.name Date: Thu, 31 Aug 2017 19:06:06 +0200 In-Reply-To: <20170831144257.oa5nm6vzihpam6kw@techsingularity.net> References: <20170831064631.2223-1-paolo.valente@linaro.org> <20170831144257.oa5nm6vzihpam6kw@techsingularity.net> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.20.5 Mime-Version: 1.0 Content-Transfer-Encoding: 8BIT X-Provags-ID: V03:K0:sAClkstj7ZzFRLQSwoVP7xqAY+HdWN2r85J3Huy+3QhRZ0vwB1y /Uos7+M1645GBhMXKPb6MilB3bzqySw7ahV4kXGAf4Bw9XgT3iLkGQmTcWzpg/81e/Hu0Ve C+elTWgmu62fGU3pNEYswIkY/F7lZ67SbydvmUaABDSMxJC18Q5CwOo3WgCzwwXGF90yK/V iCK5n1Zm7mJmThRSsDOSA== X-UI-Out-Filterresults: notjunk:1;V01:K0:tCspr2k2KZ4=:3f5vRIJcL57ig+J3TUNqPN rRp6tQ4pXgrvjz+GAloyvBchvakqMgvOl03WylDG9y1CeeQKs0i+HHiJYKcQEEXkbaRZZ4NIk uLphLKitHsqdximvS41U01fq7WRWrBAJassuPbOBRF8WYqDg1r6r2f6FE9Z+92hY2jEY4f6Ja BRsjWOMEbhwpVmrJOn18/nwEpWQpgSK2DmU9RUIfMZazi9nXIQIMulLtSfvxHq9Onk9NbaL/x 5ma5BFKrjWUq/dMlaguCfhAOWP4Pq8KsBQdNRX1x1SSjp1rRiA4HhIXiF5FWKwq00ECGW0s/F KkIzy3umWmq94kv5GGpizQfOCUYxLSOPz9lY5UPdaQRotf8M1f5AY3hpQyXiH7KVcTrnN5j3Q j7btD+EYLIXFho1+b/xm662Mi6dZWkv7j4B+VJmzNj/eMb/i3+L9kHG5oDzH45OoqpgIuaSl5 sdO+hem5EE0ptXDtb8/oJMkzrwUR8S2Zu6lGRpDZbBcodU/7EEHKy0o61Qw0VpgBAbofnCQvx G8d+5GaglTOncnKsqbQJY/nrPF8znvYV1NOz1L/lWaFhOHlbYLpmUkDTf7jgcviaBfYEHJStj pr9sY8O/uNV3MxDQON7fu1KhiDULLrUs1r5WNHdxCdLP2+oW5qWPTT9UaEgn72wtojBnR1lht nrSEdGBLDczIKKybtiPQssPnFtVCKU6Xy2roGlE83fPYwy7r2TtsidMUojj5fomIyV4mzSYAQ wkh/yQNmav7zm7cFOX3wfmlvLzju9I6wlVOoP1pMepYnuNOiHv0PUCh3qaqYxIJoRo5U5YIPP 3RoK7n0O+NhFycp8Sa8k8jzE4e4ZqWKyhCnOp/0OjsAVfKiNyQ= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2017-08-31 at 15:42 +0100, Mel Gorman wrote: > On Thu, Aug 31, 2017 at 08:46:28AM +0200, Paolo Valente wrote: > > [SECOND TAKE, with just the name of one of the tester fixed] > > > > Hi, > > while testing the read-write unfairness issues reported by Mel, I > > found BFQ failing to guarantee good responsiveness against heavy > > random sync writes in the background, i.e., multiple writers doing > > random writes and systematic fdatasync [1]. The failure was caused by > > three related bugs, because of which BFQ failed to guarantee to > > high-weight processes the expected fraction of the throughput. > > > > Queued on top of Ming's most recent series even though that's still a work > in progress. I should know in a few days how things stand. It seems to have cured an interactivity issue I regularly meet during kbuild final link/depmod phase of fat kernel kbuild, especially bad with evolution mail usage during that on spinning rust.  Can't really say for sure given this is not based on measurement. -Mike