From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH BUGFIX/IMPROVEMENT V2 0/3] three bfq fixes restoring service guarantees with random sync writes in bg To: Paolo Valente Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, ulf.hansson@linaro.org, broonie@kernel.org, mgorman@techsingularity.net, lee.tibbert@gmail.com, oleksandr@natalenko.name References: <20170831064631.2223-1-paolo.valente@linaro.org> From: Jens Axboe Message-ID: Date: Thu, 31 Aug 2017 08:21:00 -0600 MIME-Version: 1.0 In-Reply-To: <20170831064631.2223-1-paolo.valente@linaro.org> Content-Type: text/plain; charset=utf-8 List-ID: On 08/31/2017 12:46 AM, 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. > > 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. Applied for 4.14, thanks Paolo. -- Jens Axboe