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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 050C2C25B5E for ; Wed, 16 Aug 2023 20:04:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345885AbjHPUE2 (ORCPT ); Wed, 16 Aug 2023 16:04:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36330 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344763AbjHPUER (ORCPT ); Wed, 16 Aug 2023 16:04:17 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 95215E55 for ; Wed, 16 Aug 2023 13:04:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=wzBDW3Wc5hk0OfboVj+g7WZUiK4x0cKMEeegm+uAsyM=; b=gqhJHlsAmoO07vwPpYb6/uEuTF uoSbgT1KYS4PzYsWahJrcfkIU5zaimYAHEK3ppbgIicNiVmegzsPll+TeI2nMSbMzo/74NAfNQfWV QQqriFfZoDIWukQmq1Bas/p3a/YULx3DdC5WbbtfgAGW0HskdnJXt9Bu4xT6iIKDlHc/X732ivH7z rcYehzhiy5SpNTbZE+QZuQ3tqeADF3OqRBwMdZw8kYNTFbYJaPjMl2c/F52RRN3DBPLkgoOZ9/L9h WP0CYIwdMrSmyeoRPDRBrtqxsxagY7MiRVTfaJN94aZH7DR9E20xoXNZQDfFVCd6i+C+H5D1rTmpu Jvm7+6sg==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1qWMkP-00DFa1-2n; Wed, 16 Aug 2023 20:04:06 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 4CC2C3001FD; Wed, 16 Aug 2023 22:04:05 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 3A15D20FCB7B4; Wed, 16 Aug 2023 22:04:05 +0200 (CEST) Date: Wed, 16 Aug 2023 22:04:05 +0200 From: Peter Zijlstra To: Mike Galbraith Cc: Chen Yu , kernel test robot , oe-lkp@lists.linux.dev, lkp@intel.com, linux-kernel@vger.kernel.org, x86@kernel.org, Ingo Molnar Subject: Re: [tip:sched/eevdf] [sched/fair] e0c2ff903c: phoronix-test-suite.blogbench.Write.final_score -34.8% regression Message-ID: <20230816200405.GA998718@hirez.programming.kicks-ass.net> References: <202308101628.7af4631a-oliver.sang@intel.com> <20230814132935.GK776869@hirez.programming.kicks-ass.net> <20230816123716.GI980931@hirez.programming.kicks-ass.net> <20230816134059.GC982867@hirez.programming.kicks-ass.net> <3d10fbfb0171cc017e19adf39fa97a3160a76206.camel@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <3d10fbfb0171cc017e19adf39fa97a3160a76206.camel@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 16, 2023 at 05:38:20PM +0200, Mike Galbraith wrote: > On Wed, 2023-08-16 at 15:40 +0200, Peter Zijlstra wrote: > > On Wed, Aug 16, 2023 at 02:37:16PM +0200, Peter Zijlstra wrote: > > > On Mon, Aug 14, 2023 at 08:32:55PM +0200, Mike Galbraith wrote: > > > > > > > --- a/kernel/sched/fair.c > > > > +++ b/kernel/sched/fair.c > > > > @@ -875,6 +875,12 @@ static struct sched_entity *pick_eevdf(s > > > >         if (curr && (!curr->on_rq || !entity_eligible(cfs_rq, curr))) > > > >                 curr = NULL; > > > >   > > > > +       /* > > > > +        * Once selected, run the task to parity to avoid overscheduling. > > > > +        */ > > > > +       if (sched_feat(RUN_TO_PARITY) && curr) > > > > +               return curr; > > > > + > > > >         while (node) { > > > >                 struct sched_entity *se = __node_2_se(node); > > > >   > > > > > > So I read it wrong last night... but I rather like this idea. But > > > there's something missing. When curr starts a new slice it should > > > probably do a full repick and not stick with it. > > > > > > Let me poke at this a bit.. nice > > > > Something like so.. it shouldn't matter much now, but might make a > > difference once we start mixing different slice lengths. > > Hm, that stash the deadline trick _seems_ to have cured the reason I > was inspired to added that XXX hunk.. no 'ew, that's a tad harsh' > latency penalty in sight . > > Here's hoping test bots don't have a cow. You want to write up a Changelog for this, or should I attempt to write one?