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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 26185C4321D for ; Fri, 17 Aug 2018 01:57:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CEFBD214DC for ; Fri, 17 Aug 2018 01:57:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="n8Ko9l2b" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CEFBD214DC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=joelfernandes.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726272AbeHQE7I (ORCPT ); Fri, 17 Aug 2018 00:59:08 -0400 Received: from mail-pf1-f196.google.com ([209.85.210.196]:46284 "EHLO mail-pf1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725756AbeHQE7I (ORCPT ); Fri, 17 Aug 2018 00:59:08 -0400 Received: by mail-pf1-f196.google.com with SMTP id u24-v6so2807068pfn.13 for ; Thu, 16 Aug 2018 18:57:43 -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:user-agent; bh=B6gqsvwalt8gEkd2QonKP8r4uTaPxABeMG2/1QtznoQ=; b=n8Ko9l2bxCI6Uf6TOi80mqRoSG2tebBnSe4kBND/UWLM2+ZXDY+Hs5MrnItTMe+iib HuwK6M0Hm6ZfXxTQ1U9Lj8ZBGZ+kT8iiF7mr9O9EsuSZ3V6OOwv6ucIRJ0VP3fJ2wZFi G2kooBNhnubRc5c8XqCmXOmKFlfCkmrSPUPDg= 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=B6gqsvwalt8gEkd2QonKP8r4uTaPxABeMG2/1QtznoQ=; b=omZeax8PwCiFS1RUwR5hu7QRDx1xON01e4uvjFbzRILxQ81zBylziWZLIRS6aA18Uu dLVk2xWTKDjwnzcRqt/w2Cr12PVpUhta2KRnq9fVaNGE8aP+bG2kyUdJg2+x+b/3BxTp 8pWTa+ACyCK9/3uT+QTntDLA7Ejem9d5irF7d7OSujQBSWcy07CI4IcMpRouVPQU9o7H jw30S3E3D9bRBof8G5aEqpn4azr2329UrXCpbLWCRkr1iHOzhRL+AA8LJwZ+Y7aQkkoI RSMi8a3N32RLyTG85TdrEPhVwdXrcizrTjWC8pG3Xsn7U1x5XrwzpZLrnagj6YnMFYin tZYQ== X-Gm-Message-State: AOUpUlHDzG71eCwbCccivlbMcUav7MFLPLasv0DbfM+DLXcpxdSGhFmD UnFHnMDhqtbdHPtdbU/96N9Sbg== X-Google-Smtp-Source: AA+uWPxolJxxXJbxQGn9u7XDu71vjPkII1VidevtNuuOY5W1CLgp2nIXL1QXmqKMFl6/pFy41UqNzA== X-Received: by 2002:a62:ad1:: with SMTP id 78-v6mr34699837pfk.57.1534471062754; Thu, 16 Aug 2018 18:57:42 -0700 (PDT) Received: from localhost ([2620:0:1000:1601:3aef:314f:b9ea:889f]) by smtp.gmail.com with ESMTPSA id n12-v6sm751508pfh.146.2018.08.16.18.57.41 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 16 Aug 2018 18:57:41 -0700 (PDT) Date: Thu, 16 Aug 2018 18:57:41 -0700 From: Joel Fernandes To: Morten Rasmussen Cc: peterz@infradead.org, mingo@redhat.com, valentin.schneider@arm.com, dietmar.eggemann@arm.com, vincent.guittot@linaro.org, gaku.inami.xh@renesas.com, linux-kernel@vger.kernel.org, tkjos@google.com Subject: Re: [PATCHv4 00/12] sched/fair: Migrate 'misfit' tasks on asymmetric capacity systems Message-ID: <20180817015741.GA3039@joelaf.mtv.corp.google.com> References: <1530699470-29808-1-git-send-email-morten.rasmussen@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1530699470-29808-1-git-send-email-morten.rasmussen@arm.com> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 04, 2018 at 11:17:38AM +0100, Morten Rasmussen wrote: > On asymmetric cpu capacity systems (e.g. Arm big.LITTLE) it is crucial > for performance that cpu intensive tasks are aggressively migrated to > high capacity cpus as soon as those become available. The capacity > awareness tweaks already in the wake-up path can't handle this as such > tasks might run or be runnable forever. If they happen to be placed on a > low capacity cpu from the beginning they are stuck there forever while > high capacity cpus may have become available in the meantime. > > To address this issue this patch set introduces a new "misfit" > load-balancing scenario in periodic/nohz/newly idle balance which tweaks > the load-balance conditions to ignore load per capacity in certain > cases. Since misfit tasks are commonly running alone on a cpu, more > aggressive active load-balancing is needed too. > > The fundamental idea of this patch set has been in Android kernels for a > long time and is absolutely essential for consistent performance on > asymmetric cpu capacity systems. > > The patches have been tested on: > 1. Arm Juno (r0): 2+4 Cortex A57/A53 > 2. Hikey960: 4+4 Cortex A73/A53 > Thanks for posting these, we have been carrying it in the Android Common Kernel for some time. They have been useful for Android systems. Reviewed-by: Joel Fernandes (Google) thanks, - Joel