From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <1504200711.666.27.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: Paolo Valente Cc: Mel Gorman , Jens Axboe , linux-block , Linux Kernel Mailing List , Ulf Hansson , broonie@kernel.org, lee.tibbert@gmail.com, oleksandr@natalenko.name Date: Thu, 31 Aug 2017 19:31:51 +0200 In-Reply-To: <970115C1-6336-458D-BBD5-3E5054C4553D@linaro.org> References: <20170831064631.2223-1-paolo.valente@linaro.org> <20170831144257.oa5nm6vzihpam6kw@techsingularity.net> <1504199166.666.11.camel@gmx.de> <970115C1-6336-458D-BBD5-3E5054C4553D@linaro.org> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 List-ID: On Thu, 2017-08-31 at 19:12 +0200, Paolo Valente wrote: > > Il giorno 31 ago 2017, alle ore 19:06, Mike Galbraith h= a scritto: > >=20 > > 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 = work > >> in progress. I should know in a few days how things stand. > >=20 > > 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. > > >=20 >=20 > Great! Actually, when I found these bugs, I thought also about the > issues you told me you experienced with updatedb running. But then I > forgot to tell you that these fixes might help. I'm going to actively test that, because that is every bit as infuriating as the evolution thing, only updatedb is nukable. =C2=A0In fact= , it infuriated me to the point that it no longer has a crontab entry, runs only when I decide to run it. =C2=A0At this point, I'll be pretty surprised if that rotten is still alive. -Mike