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[23.128.96.18]) by mx.google.com with ESMTP id gx16si6004511ejc.33.2021.09.23.05.43.31; Thu, 23 Sep 2021 05:43:55 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=UtjhCVmE; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241078AbhIWMnW (ORCPT + 99 others); Thu, 23 Sep 2021 08:43:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50330 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241123AbhIWMnC (ORCPT ); Thu, 23 Sep 2021 08:43:02 -0400 Received: from mail-qk1-x72c.google.com (mail-qk1-x72c.google.com [IPv6:2607:f8b0:4864:20::72c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2A8B7C061767 for ; Thu, 23 Sep 2021 05:41:18 -0700 (PDT) Received: by mail-qk1-x72c.google.com with SMTP id 194so21223618qkj.11 for ; Thu, 23 Sep 2021 05:41:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=0GWvNudSvOsNq1z9e3rrCS7rGXQnler1Q9GZARzjsOE=; b=UtjhCVmEmMisTpTnxznpACr8MS2kOzLEWDLWLd6Gr1mz5hs8doZbdeapQuugdl8+t1 ZDp1aSI9O/paJXFybAxY9dg3D7OVG2WKN/3Yj7kAAsSswLDTwgFsQuph65Z9AYdzJ3gH X0Rxj4EP7sZXnEOzjpDI7R1cIEodvlqp+fzcCVQS3D2rJ00LHXUm4Lp2iSdnqXuPp5p5 tWLLWW+RiNEfAHam6JMp7ph77+9LE3UettkIHmtf10Reweu5NknO/pyI6hkoJ4mjqFyR p4FkWptSVtP6PBt8BVIc5gRltxZXIUK19G4ljbd3xWYDYuWlrU85pdQVAidQPAWWggpq aRVw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=0GWvNudSvOsNq1z9e3rrCS7rGXQnler1Q9GZARzjsOE=; b=feZwWe+N83mfWvWn/etDIMck6FbTcHPH7c78MDz3G4FWP9AcJkPc3uC9v4ytu3b240 7F29lTTLvii3SwkGoWxm2B6WT+7i7qFJg2jSAJdVFK2Js/tTnjTEhi10CPMtQsVXveKU P1HGXDYPUq3eT9M9QNY/J4v6fNbOhD8P4+lQ+6IG66io21blQqvmlk7QGYLdlUU8u32z gZh6SUuy8hM3bgBaG387Oyyr2mjyoGsd5NTZlORrX6FzdvgIe4m36/Q2LSuJJgXNlYq8 a9o3T07cXivmw6SJC1+zBMSo/b4lHKhkhOiWNgbUiVTs7FvhQN97IuMYhlqiA3Wl8eh1 30uQ== X-Gm-Message-State: AOAM533Pg19HLFQA6BCOw+i1gNAzs1bF1+l6aoMDFeTATE2O7iOvVkzN uomTx3XrJn8QZ7TLfkAB6XGyTYXgSM1C27DOw7p5iw== X-Received: by 2002:a25:d9c8:: with SMTP id q191mr5537297ybg.61.1632400877314; Thu, 23 Sep 2021 05:41:17 -0700 (PDT) MIME-Version: 1.0 References: <20210920142614.4891-1-mgorman@techsingularity.net> <20210920142614.4891-3-mgorman@techsingularity.net> <22e7133d674b82853a5ee64d3f5fc6b35a8e18d6.camel@gmx.de> <20210921103621.GM3959@techsingularity.net> <20210922132002.GX3959@techsingularity.net> <20210922150457.GA3959@techsingularity.net> <20210922173853.GB3959@techsingularity.net> <50400427070018eff83b0782d2e26c0cc9ff4521.camel@gmx.de> In-Reply-To: <50400427070018eff83b0782d2e26c0cc9ff4521.camel@gmx.de> From: Vincent Guittot Date: Thu, 23 Sep 2021 14:41:06 +0200 Message-ID: Subject: Re: [PATCH 2/2] sched/fair: Scale wakeup granularity relative to nr_running To: Mike Galbraith Cc: Mel Gorman , Peter Zijlstra , Ingo Molnar , Valentin Schneider , Aubrey Li , Barry Song , Srikar Dronamraju , LKML Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 23 Sept 2021 at 11:22, Mike Galbraith wrote: > > On Thu, 2021-09-23 at 10:40 +0200, Vincent Guittot wrote: > > > > a 100us value should even be enough to fix Mel's problem without > > impacting common wakeup preemption cases. > > It'd be nice if it turn out to be something that simple, but color me > skeptical. I've tried various preemption throttling schemes, and while Let's see what the results will show. I tend to agree that this will not be enough to cover all use cases and I don't see any other way to cover all cases than getting some inputs from the threads about their latency fairness which bring us back to some kind of latency niceness value > it was trivial to get promising results, my scheme always managed to > harm something. Everything I ever tried, I ended up tossing. > > -Mike