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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED, 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 E3A5FC3A589 for ; Fri, 16 Aug 2019 02:33:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C221621874 for ; Fri, 16 Aug 2019 02:33:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726770AbfHPCdZ (ORCPT ); Thu, 15 Aug 2019 22:33:25 -0400 Received: from out30-131.freemail.mail.aliyun.com ([115.124.30.131]:37697 "EHLO out30-131.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726702AbfHPCdV (ORCPT ); Thu, 15 Aug 2019 22:33:21 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R361e4;CH=green;DM=||false|;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04400;MF=aaron.lu@linux.alibaba.com;NM=1;PH=DS;RN=22;SR=0;TI=SMTPD_---0TZayJcx_1565922789; Received: from aaronlu(mailfrom:aaron.lu@linux.alibaba.com fp:SMTPD_---0TZayJcx_1565922789) by smtp.aliyun-inc.com(127.0.0.1); Fri, 16 Aug 2019 10:33:15 +0800 Date: Fri, 16 Aug 2019 10:33:09 +0800 From: Aaron Lu To: Dario Faggioli Cc: Tim Chen , Julien Desfossez , "Li, Aubrey" , Aubrey Li , Subhra Mazumdar , Vineeth Remanan Pillai , Nishanth Aravamudan , Peter Zijlstra , Ingo Molnar , Thomas Gleixner , Paul Turner , Linus Torvalds , Linux List Kernel Mailing , =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker , Kees Cook , Greg Kerr , Phil Auld , Valentin Schneider , Mel Gorman , Pawan Gupta , Paolo Bonzini Subject: Re: [RFC PATCH v3 00/16] Core scheduling v3 Message-ID: <20190816023309.GA78614@aaronlu> References: <20190619183302.GA6775@sinkpad> <20190718100714.GA469@aaronlu> <20190725143003.GA992@aaronlu> <20190726152101.GA27884@sinkpad> <7dc86e3c-aa3f-905f-3745-01181a3b0dac@linux.intel.com> <20190802153715.GA18075@sinkpad> <69cd9bca-da28-1d35-3913-1efefe0c1c22@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 15, 2019 at 06:09:28PM +0200, Dario Faggioli wrote: > On Wed, 2019-08-07 at 10:10 -0700, Tim Chen wrote: > > On 8/7/19 1:58 AM, Dario Faggioli wrote: > > > > > Since I see that, in this thread, there are various patches being > > > proposed and discussed... should I rerun my benchmarks with them > > > applied? If yes, which ones? And is there, by any chance, one (or > > > maybe > > > more than one) updated git branch(es)? > > > > > Hi Dario, > > > Hi Tim! > > > Having an extra set of eyes are certainly welcomed. > > I'll give my 2 cents on the issues with v3. > > > Ok, and thanks a lot for this. > > > 1) Unfairness between the sibling threads > > ----------------------------------------- > > One sibling thread could be suppressing and force idling > > the sibling thread over proportionally. Resulting in > > the force idled CPU not getting run and stall tasks on > > suppressed CPU. > > > > > > [...] > > > > 2) Not rescheduling forced idled CPU > > ------------------------------------ > > The forced idled CPU does not get a chance to re-schedule > > itself, and will stall for a long time even though it > > has eligible tasks to run. > > > > [...] > > > > 3) Load balancing between CPU cores > > ----------------------------------- > > Say if one CPU core's sibling threads get forced idled > > a lot as it has mostly incompatible tasks between the siblings, > > moving the incompatible load to other cores and pulling > > compatible load to the core could help CPU utilization. > > > > So just considering the load of a task is not enough during > > load balancing, task compatibility also needs to be considered. > > Peter has put in mechanisms to balance compatible tasks between > > CPU thread siblings, but not across cores. > > > > [...] > > > Ok. Yes, as said, I've been trying to follow the thread, but thanks a > lot again for this summary. > > As said, I'm about to have numbers for the repo/branch I mentioned. > > I was considering whether to also re-run the benchmarking campaign with > some of the patches that floated around within this thread. Now, thanks > to your summary, I have an even clearer picture about which patch does > what, and that is indeed very useful. > > I'll see about putting something together. I'm thinking of picking: > > https://lore.kernel.org/lkml/b7a83fcb-5c34-9794-5688-55c52697fd84@linux.intel.com/ > https://lore.kernel.org/lkml/20190725143344.GD992@aaronlu/ > > And maybe even (part of): > https://lore.kernel.org/lkml/20190810141556.GA73644@aaronlu/#t > > If anyone has ideas or suggestions about whether or not this choice > makes sense, feel free to share. :-) Makes sense to me. patch3 in the last link is slightly better than the one in the 2nd link, so just use that instead. Thanks, Aaron > Also, I only have another week before leaving, so let's see what I > manage to actually run, and then share here, by then. > > Thanks and Regards > -- > Dario Faggioli, Ph.D > http://about.me/dario.faggioli > Virtualization Software Engineer > SUSE Labs, SUSE https://www.suse.com/ > ------------------------------------------------------------------- > <> (Raistlin Majere) >