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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 A1BE8C352AA for ; Tue, 1 Oct 2019 13:31:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 76E2A21920 for ; Tue, 1 Oct 2019 13:31:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="D1mD/BsE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388536AbfJANbX (ORCPT ); Tue, 1 Oct 2019 09:31:23 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:45344 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725821AbfJANbX (ORCPT ); Tue, 1 Oct 2019 09:31:23 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1569936682; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=KorGO3/zt+fwbdt/ZEhjTUWoi53sFfxZoLftxHGs9Z4=; b=D1mD/BsELLCYTJTKJ8PDE4WoshkCaTnrZJwi+/stcdIC8T/F7/Qu8IPNjBjZ+fDPkRz5ZF +QqscD2x8TUtFmuDsTR5w56/zVhwSogxFB66hiv+vBWez5xHOBBI6C2/9fOLLK5+Uwl1W+ DvVtifBawoG9soLYm0LpIB+2XztOgIg= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-227-E0z3Tq1OM3-wcPlGo49m6w-1; Tue, 01 Oct 2019 09:31:19 -0400 Received: by mail-wr1-f71.google.com with SMTP id t11so6014909wrq.19 for ; Tue, 01 Oct 2019 06:31:19 -0700 (PDT) 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:user-agent; bh=KorGO3/zt+fwbdt/ZEhjTUWoi53sFfxZoLftxHGs9Z4=; b=iH0H0blzDmwFUCWlWKWqdUJucbmp75I8U0sggOlR12sm0TKNd2f3JeEli/QWEVg/It pkNxiuvqnVmeJvAwvnjYavc3CJN5U4uqJl3i+HFsPWLQAY34yDGEo7Zsvc7Qz3pNR3q+ F9kGCwnx2YNCi/4a2nI52fZ8cDduYr/Faa1lt8TICLBE7AIi/fvh8ES2roTwwSSOjQuL tEVQVtuUJ54/ZPUPi+IKfYjg9CgFtYD2yMxHXAOQ/lJTiF2lar6K/HcQ6tqF9T9FukhW e7mgbb7KuOtiqe9SubPlRbDFvg45fHEiXs3yxmCVHYDq3hFhjvFJpO9JYlz22aQ1dv7r kZWg== X-Gm-Message-State: APjAAAV1sY7nWBwJTAfdRfdmEja9vRWC9lHTFZegUtSe6jzZH6af6cqq Wje4BRmeKMiqidvKPcYSmOhtztvL5Mxf5fQhwENK9DfjpOSgM47KceyF1u9wVYwygjH52YscVdI 9IRk+hhdKBIHibeRGs3zh1W8W X-Received: by 2002:a5d:6a06:: with SMTP id m6mr17677605wru.190.1569936678471; Tue, 01 Oct 2019 06:31:18 -0700 (PDT) X-Google-Smtp-Source: APXvYqxMq1gs5+tTkwVxPJSNX7tFUGYkmIfQHbLYzUUn4Dh1gi0aI91buvk1r+Hg5iwYRUrQmHj12Q== X-Received: by 2002:a5d:6a06:: with SMTP id m6mr17677578wru.190.1569936678216; Tue, 01 Oct 2019 06:31:18 -0700 (PDT) Received: from localhost.localdomain ([151.29.237.241]) by smtp.gmail.com with ESMTPSA id t14sm17350431wrs.6.2019.10.01.06.31.16 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 01 Oct 2019 06:31:17 -0700 (PDT) Date: Tue, 1 Oct 2019 15:31:15 +0200 From: Juri Lelli To: Valentin Schneider Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, peterz@infradead.org, vincent.guittot@linaro.org, tglx@linutronix.de, qais.yousef@arm.com, Steven Rostedt Subject: Re: [PATCH v2 0/4] sched/fair: Active balancer RT/DL preemption fix Message-ID: <20191001133115.GC6481@localhost.localdomain> References: <20190815145107.5318-1-valentin.schneider@arm.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.11.3 (2019-02-01) X-MC-Unique: E0z3Tq1OM3-wcPlGo49m6w-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Valentin, On 01/10/19 11:29, Valentin Schneider wrote: > (expanded the Cc list) > RT/DL folks, any thought on the thing? Even if I like your idea and it looks theoretically the right thing to do, I'm not sure we want it in practice if it adds complexity to CFS. I personally never noticed this kind of interference from CFS, but, at the same time, for RT we usually like more to be safe than sorry. However, since this doesn't seem to be bullet-proof (as you also say), I guess it all boils down again to complexity vs. practical benefits. Best, Juri