From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750918AbdHaGlY (ORCPT ); Thu, 31 Aug 2017 02:41:24 -0400 Received: from vulcan.natalenko.name ([104.207.131.136]:13532 "EHLO vulcan.natalenko.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750732AbdHaGlX (ORCPT ); Thu, 31 Aug 2017 02:41:23 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 vulcan.natalenko.name 3D04323EC51 Authentication-Results: vulcan.natalenko.name; dmarc=fail (p=none dis=none) header.from=natalenko.name MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Thu, 31 Aug 2017 08:41:18 +0200 From: oleksandr@natalenko.name To: Paolo Valente Cc: Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, ulf.hansson@linaro.org, broonie@kernel.org, mgorman@techsingularity.net, lee.tibbert@gmail.com Subject: Re: [PATCH BUGFIX/IMPROVEMENT 0/3] three bfq fixes restoring service guarantees with random sync writes in bg In-Reply-To: <20170831061020.4426-1-paolo.valente@linaro.org> References: <20170831061020.4426-1-paolo.valente@linaro.org> Message-ID: <8b2ad38d79334a156f18904cc2dd3509@natalenko.name> User-Agent: Roundcube Webmail/1.3.0 ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=natalenko.name; s=arc-20170712; t=1504161679; h=from:subject:date:message-id:to:cc:mime-version:content-type:content-transfer-encoding:in-reply-to:references; bh=VUQvNpMxdFFO7VKfU/fc5uo+Ef0u0q5Y0kPdhP37uds=; b=O8z3sozw4r/Y9mgzb/5h/arjTEtKNmag625VNAsjB4HtZb/aO4Pe3Uxjup+wUQl2CBNTqR 1QqdV40eW5mKed3NvF1lkviMQ0l9RWuDwvxvc15bPb22CVJ5ilpcqpS1U6SZJh9ssyLbge FnenVmzJAjXhibEi+rr7SkD28zqSCUA= ARC-Seal: i=1; s=arc-20170712; d=natalenko.name; t=1504161679; a=rsa-sha256; cv=none; b=tLTuybjjsNw+aCh7U2YTHSbyx1YJvHS2OVIJY4MGob90+0/X/tpZmDes0up+BwT6wGeot8ufv6rpSdbC3GgTkTqDCmmDjugI4J3acPgkYc4APfpGbcflSRE1miqdSriMJ8TNHpfVxWBy0gpsM+7ClipuNx/0ZBzwcRgb4eXj7UE= ARC-Authentication-Results: i=1; auth=pass smtp.auth=oleksandr@natalenko.name smtp.mailfrom=oleksandr@natalenko.name Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Tested-by: Oleksander Natalenko I'm "Oleksandr" :). 31.08.2017 08:10, Paolo Valente wrote: > 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. > > The three patches in this series fix these bugs. These fixes restore > the usual BFQ service guarantees (and thus optimal responsiveness > too), against the above background workload and, probably, against > other similar workloads. > > Thanks, > Paolo > > [1] https://lkml.org/lkml/2017/8/9/957 > > Paolo Valente (3): > block, bfq: make lookup_next_entity push up vtime on expirations > block, bfq: remove direct switch to an entity in higher class > block, bfq: guarantee update_next_in_service always returns an > eligible entity > > block/bfq-iosched.c | 4 +-- > block/bfq-iosched.h | 4 +-- > block/bfq-wf2q.c | 91 > ++++++++++++++++++++++++++++++++--------------------- > 3 files changed, 60 insertions(+), 39 deletions(-) > > -- > 2.10.0