From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5695DC2BA19 for ; Thu, 16 Apr 2020 00:02:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2DD862078B for ; Thu, 16 Apr 2020 00:02:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="wlTvb45C" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391003AbgDPACq (ORCPT ); Wed, 15 Apr 2020 20:02:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43280 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1730983AbgDPACm (ORCPT ); Wed, 15 Apr 2020 20:02:42 -0400 Received: from mail-qk1-x744.google.com (mail-qk1-x744.google.com [IPv6:2607:f8b0:4864:20::744]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E5876C061A0C for ; Wed, 15 Apr 2020 17:02:38 -0700 (PDT) Received: by mail-qk1-x744.google.com with SMTP id l78so3880117qke.7 for ; Wed, 15 Apr 2020 17:02:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=X6Mgw1nun/Uy4a+IPSrxBx2LY1+xrpHKaA4zi6L+JLQ=; b=wlTvb45CffggOZUiA2YX0BJzHY0Y+vT7fwA78EoFTbc+3f3+3rLQ2AY2kK4MYR8RyD UmqAsBbarIU+pg4GnT71VBsriKivmOVDIEKHlMC0mbvNIR7SLexkeg+kBIkULlDxAJTr ghuksWcv8gH4N/nKbtuy1gLDp2Qf0MCNRQy4o= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=X6Mgw1nun/Uy4a+IPSrxBx2LY1+xrpHKaA4zi6L+JLQ=; b=QMDwR/NsKsa1ehrrUWXsGUT4i6faf7YzEnOc0qSPe7izmxbGvBhV1fwAeLzqdgBQX0 Zh91GXrzo/fxkk5qS5Fj4u/i1+TyKMRJACzkw+TWD/CAF6p3bGx0jIVjuQ8hSeGwoLZy wTB/OyykXwxkl4Cv3z6UIoA8Pgsg3jE9wtga8heyRUERL0PbFxjeHObZ1Ub9Mxqh8fLt 6jK37l7hY2ILwQ+dlhPxHGCFKZUpSvwJT25e0d8BOUmWaenVI2I8afDi/WGJQAiBwZzP aZDLIUsrWhAy6XRN2ASq2G3Ew9PzSj73JjOvvYhHdb7fvQn3wkkTaRWbFL11JxNKpskg cmoQ== X-Gm-Message-State: AGi0PuY3XQyQ9f8m5buC71XtUHy00NJTo3+4DQ6xR22mpLIkFftrbjZX IwNiDijrAXicK7YjMvDC8pxyBA== X-Google-Smtp-Source: APiQypIbxc8jo4K13VEY2oIrO9aS6ndUQFg674L5mw7lqTQJWvJmBKuHi5gEAokl3owq+1tfBgo7Jw== X-Received: by 2002:a37:5004:: with SMTP id e4mr28829285qkb.18.1586995357890; Wed, 15 Apr 2020 17:02:37 -0700 (PDT) Received: from localhost ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id x55sm4705228qtk.3.2020.04.15.17.02.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Apr 2020 17:02:36 -0700 (PDT) Date: Wed, 15 Apr 2020 20:02:35 -0400 From: Joel Fernandes To: Qais Yousef Cc: Peter Zijlstra , Patrick Bellasi , Subhra Mazumdar , linux-kernel@vger.kernel.org, mingo@redhat.com, tglx@linutronix.de, steven.sistare@oracle.com, dhaval.giani@oracle.com, daniel.lezcano@linaro.org, vincent.guittot@linaro.org, viresh.kumar@linaro.org, tim.c.chen@linux.intel.com, mgorman@techsingularity.net, parth@linux.ibm.com Subject: Re: [RFC PATCH 1/9] sched,cgroup: Add interface for latency-nice Message-ID: <20200416000235.GA211099@google.com> References: <20190830174944.21741-1-subhra.mazumdar@oracle.com> <20190830174944.21741-2-subhra.mazumdar@oracle.com> <20190905083127.GA2332@hirez.programming.kicks-ass.net> <87r24v2i14.fsf@arm.com> <20190905104616.GD2332@hirez.programming.kicks-ass.net> <20190905111346.2w6kuqrdvaqvgilu@e107158-lin.cambridge.arm.com> <20190905113002.GK2349@hirez.programming.kicks-ass.net> <20190905114725.ehi5ea6qg3rychlz@e107158-lin.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190905114725.ehi5ea6qg3rychlz@e107158-lin.cambridge.arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 05, 2019 at 12:47:26PM +0100, Qais Yousef wrote: > On 09/05/19 13:30, Peter Zijlstra wrote: > > On Thu, Sep 05, 2019 at 12:13:47PM +0100, Qais Yousef wrote: > > > On 09/05/19 12:46, Peter Zijlstra wrote: > > > > > > This is important because we want to be able to bias towards less > > > > importance to (tail) latency as well as more importantance to (tail) > > > > latency. > > > > > > > > Specifically, Oracle wants to sacrifice (some) latency for throughput. > > > > Facebook OTOH seems to want to sacrifice (some) throughput for latency. > > > > > > Another use case I'm considering is using latency-nice to prefer an idle CPU if > > > latency-nice is set otherwise go for the most energy efficient CPU. > > > > > > Ie: sacrifice (some) energy for latency. > > > > > > The way I see interpreting latency-nice here as a binary switch. But > > > maybe we can use the range to select what (some) energy to sacrifice > > > mean here. Hmmm. > > > > It cannot be binary, per definition is must be ternary, that is, <0, ==0 > > and >0 (or middle value if you're of that persuasion). > > I meant I want to use it as a binary. > > > > > In your case, I'm thinking you mean >0, we want to lower the latency. > > Yes. As long as there's an easy way to say: does this task care about latency > or not I'm good. Qais, Peter, all, For ChromeOS (my team), we are planning to use the upstream uclamp mechanism instead of the out-of-tree schedtune mechanism to provide EAS with the latency-sensitivity (binary/ternary) hint. ChromeOS is thankfully quite a bit upstream focussed :) However, uclamp is missing an attribute to provide this biasing to EAS as we know. What was the consensus on adding a per-task attribute to uclamp for providing this? Happy to collaborate on this front. thanks, - Joel > > Anyway; there were a number of things mentioned at OSPM that we could > > tie into this thing and finding sensible mappings is going to be a bit > > of trial and error I suppose. > > > > But as patrick said; we're very much exporting a BIAS knob, not a set of > > behaviours. > > Agreed. I just wanted to say that the way this range is going to be > interpreted will differ from path to path and we need to consider that in the > final mapping. Especially from the final user's perspective of what setting > this value ultimately means to them. > > -- > Qais Yousef