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[146.241.2.120]) by smtp.gmail.com with ESMTPSA id e19sm12792365wrc.25.2018.11.30.10.53.07 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 30 Nov 2018 10:53:08 -0800 (PST) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 12.0 \(3445.100.39\)) Subject: Re: [PATCH V2 00/10] unify the interface of the proportional-share policy in blkio/io From: Paolo Valente In-Reply-To: <20181130184256.GI2509588@devbig004.ftw2.facebook.com> Date: Fri, 30 Nov 2018 19:53:07 +0100 Cc: Jens Axboe , Greg Kroah-Hartman , Li Zefan , Angelo Ruocco , Dennis Zhou , Josef Bacik , Liu Bo , Bart Van Assche , Johannes Weiner , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, ulf.hansson@linaro.org, linus.walleij@linaro.org, broonie@kernel.org, oleksandr@natalenko.name, cgroups@vger.kernel.org, linux-doc@vger.kernel.org, Jonathan Corbet Content-Transfer-Encoding: quoted-printable Message-Id: <5534B7D4-A5D9-4F44-9620-970A7F9EC140@linaro.org> References: <20181119103424.3853-1-paolo.valente@linaro.org> <20181120162816.GV2509588@devbig004.ftw2.facebook.com> <25296DAE-73EC-46CC-9A98-A8B7E9017BB7@linaro.org> <7D7FAB43-5F62-4402-A9B3-E7C2E30AE680@linaro.org> <20181130184256.GI2509588@devbig004.ftw2.facebook.com> To: 'Paolo Valente' via bfq-iosched X-Mailer: Apple Mail (2.3445.100.39) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Il giorno 30 nov 2018, alle ore 19:42, Tejun Heo ha = scritto: >=20 > Hello, Paolo. >=20 > On Fri, Nov 30, 2018 at 07:23:24PM +0100, Paolo Valente wrote: >>> Then we understood that exactly the same happens with throttling, in >>> case the latter is activated on different devices w.r.t. bfq. >>>=20 >>> In addition, the same may happen, in the near future, with the >>> bandwidth controller Josef is working on. If the controller can be >>> configured per device, as with throttling, then statistics may = differ, >>> for the same interface files, between bfq, throttling and that >>> controller. >=20 > So, regardless of how all these are implemented, what's presented to > user should be consistent and clear. There's no other way around it. > Only what's relevant should be visible to userspace. >=20 >> have you had time to look into this? Any improvement to this >> interface is ok for us. We are only interested in finally solving = this >> interface issue, as, for what concerns us directly, it has been >> preventing legacy code to use bfq for years. >=20 > Unfortunately, I don't have any implementation proposal, but we can't > show things this way to userspace. >=20 Well, this is not very helpful to move forward :) Let me try to repeat the problem, to try to help you help us unblock the situation. If we have multiple entities attached to the same interface output file, you don't find it clear that each entity shows the number it wants to show. But you have no idea either of how that differentiated information should be shown. Is this the situation, or is the problem somewhere 'above' this level? If the problem is as I described it, here are some proposal attempts: 1) Do you want file sharing to be allowed only if all entities will output the same number? (this seems excessive, but maybe it makes sense) 2) Do you want only one number to be shown, equal to the sum of the numbers of each entity? (in some cases, this may make sense) 3) Do you prefer an average? 4) Do you have any other idea, even if just germinal? Looking forward to your feedback, Paolo=20 > Thanks. >=20 > --=20 > tejun >=20 > --=20 > You received this message because you are subscribed to the Google = Groups "bfq-iosched" group. > To unsubscribe from this group and stop receiving emails from it, send = an email to bfq-iosched+unsubscribe@googlegroups.com. > For more options, visit https://groups.google.com/d/optout.