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[155.185.122.167]) by smtp.gmail.com with ESMTPSA id h125sm2539418wmf.31.2019.09.11.01.18.55 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 11 Sep 2019 01:18:56 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.8\)) Subject: Re: [PATCH 08/10] blkcg: implement blk-iocost From: Paolo Valente In-Reply-To: <20190910160855.GS2263813@devbig004.ftw2.facebook.com> Date: Wed, 11 Sep 2019 10:18:53 +0200 Cc: =?utf-8?Q?Michal_Koutn=C3=BD?= , Johannes Weiner , clm@fb.com, dennisz@fb.com, newella@fb.com, Li Zefan , Jens Axboe , Josef Bacik , Josef Bacik , kernel-team@fb.com, Rik van Riel , cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: References: <20190828220600.2527417-1-tj@kernel.org> <20190828220600.2527417-9-tj@kernel.org> <20190910125513.GA6399@blackbody.suse.cz> <20190910160855.GS2263813@devbig004.ftw2.facebook.com> To: Tejun Heo X-Mailer: Apple Mail (2.3445.104.8) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org > Il giorno 10 set 2019, alle ore 18:08, Tejun Heo ha = scritto: >=20 > Hello, Michal. >=20 > On Tue, Sep 10, 2019 at 02:55:14PM +0200, Michal Koutn=C3=BD wrote: >> This adds the generic io.weight attribute. How will this compose with >> the weight from IO schedulers? (AFAIK, only BFQ allows proportional >> control as of now. +CC Paolo.) >=20 > The two being enabled at the same time doesn't make sense, so we can > just switch over to bfq when bfq is selected as the iosched. I asked > what Paolo wanted to do in terms of interface a couple times now but > didn't get an answer and he posted a patch which makes the two > controllers conflict, so.... Paolo, so it looks like you want to > rename all bfq files to drop the bfq prefix, right? Yep, mainly because ... this is the solution you voted and you yourself proposed [1] :) [1] https://patchwork.kernel.org/patch/10988261/ > I can implement > the switching if so. >=20 That would be perfect. Thanks, Paolo >> I see this attributes are effectively per-cgroup per-device. = Apparently, >> one device should have only one weight across hierarchy. Would it = make >> sense to have io.bfq.weight and io.cost.weight with disjunctive = devices? >=20 > It never makes sense to have both enabled, so I don't think that > interface makes sense. >=20 >>> + .name =3D "cost.qos", >>> + .flags =3D CFTYPE_ONLY_ON_ROOT, >>> [...] >>> + .name =3D "cost.model", >>> + .flags =3D CFTYPE_ONLY_ON_ROOT, >> I'm concerned that these aren't true cgroup attributes. The root = cgroup >> would act as container for global configuration options. Wouldn't = these >> values better fit as (configurable) attributes of the respective >> devices? >=20 > Initially, I put them under block device sysfs but it was too clumsy > with different config file formats and all. I think it's better to > have global controller configs at the root cgroup. >=20 >> Secondly, how is CFTYPE_ONLY_ON_ROOT supposed to be presented in = cgroup >> namespaces? >=20 > Not at all. These are system-wide configs. cgroup namespaces > shouldn't have anything which aren't in non-root cgroups. >=20 > Thanks. >=20 > --=20 > tejun