From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752662Ab3BUBmv (ORCPT ); Wed, 20 Feb 2013 20:42:51 -0500 Received: from mga11.intel.com ([192.55.52.93]:14091 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751840Ab3BUBmt (ORCPT ); Wed, 20 Feb 2013 20:42:49 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.84,705,1355126400"; d="scan'208";a="293892480" Message-ID: <51257BAF.9050204@intel.com> Date: Thu, 21 Feb 2013 09:43:11 +0800 From: Alex Shi User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120912 Thunderbird/15.0.1 MIME-Version: 1.0 To: Ingo Molnar CC: torvalds@linux-foundation.org, mingo@redhat.com, peterz@infradead.org, tglx@linutronix.de, akpm@linux-foundation.org, arjan@linux.intel.com, bp@alien8.de, pjt@google.com, namhyung@kernel.org, efault@gmx.de, vincent.guittot@linaro.org, gregkh@linuxfoundation.org, preeti@linux.vnet.ibm.com, viresh.kumar@linaro.org, linux-kernel@vger.kernel.org, morten.rasmussen@arm.com Subject: Re: [patch v5 04/15] sched: add sched balance policies in kernel References: <1361164062-20111-1-git-send-email-alex.shi@intel.com> <1361164062-20111-5-git-send-email-alex.shi@intel.com> <20130220093751.GA2444@gmail.com> <5124D253.6090606@intel.com> <20130220154101.GA13388@gmail.com> In-Reply-To: <20130220154101.GA13388@gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/20/2013 11:41 PM, Ingo Molnar wrote: > > * Alex Shi wrote: > >> Now there is just 2 types policy: performance and >> powersaving(with 2 degrees, powersaving and balance). > > I don't think we really want to have 'degrees' to the policies > at this point - we want each policy to be extremely good at what > it aims to do: > > - 'performance' should finish jobs in in the least amount of > time possible. No ifs and whens. > > - 'power saving' should finish jobs with the least amount of > watts consumed. No ifs and whens. > >> powersaving policy will try to assign one task to each LCPU, >> whichever the LCPU is SMT thread or a core. The balance policy >> is also a kind of powersaving policy, just a bit less >> aggressive. It will try to assign tasks according group >> capacity, one task to one capacity. > > The thing is, 'a bit less aggressive' is an awfully vague > concept to maintain on a long term basis - while the two > definitions above are reasonably deterministic which can be > measured and improved upon. > > Those two policies and definitions are also much easier to > communicate to user-space and to users - it's much easier to > explain what each policy is supposed to do. > > I'd be totally glad if we got so far that those two policies > work really well. Any further nuance visible at the ABI level is > I think many years down the road - if at all. Simple things > first - those are complex enough already. Thanks for comments! I will remove the 'balance' policy. > > Thanks, > > Ingo > -- Thanks Alex