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 46707CD98F7 for ; Wed, 11 Oct 2023 07:34:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344868AbjJKHeJ (ORCPT ); Wed, 11 Oct 2023 03:34:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39756 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345499AbjJKHeA (ORCPT ); Wed, 11 Oct 2023 03:34:00 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AE95992 for ; Wed, 11 Oct 2023 00:33:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=bb4TaTpxv5J8iSs+A5abhWEGldd9r3gdni3LZgLtLDA=; b=mZ6PbUSdKl1FJmB0ShPmISe2v0 GM8FD2rBcJrbVNTNzv0qN3qmBFiaproN8z6lsS+DoUfIN88tSKuHVZvFWwfg5QHvMGmpDce1bL9hR Sdwn+ETvYM69aXB1uB9Ueb99gKF7qWnab+WTyitImNoAnzg0Knc8KLBmYjlyJSGUEUkyMCsxJseg/ WCWjozLWwmT9zVJ9WCX4fTB3AoVuQ89WgfOof0XJGiuH2TBwPlTcJzYCzSGTmjaJv4CTfAPUiLpJ5 7xyS4TZIfwHb1dKYEEyrWvAHsbx047Vh7GgqUwKUlhpmp2+mC4g/rHk9WlcrqenPOZz1ZzHBqRZEV g1RQrvdA==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1qqTiX-009UTG-NS; Wed, 11 Oct 2023 07:33:17 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 62D8D30026F; Wed, 11 Oct 2023 09:33:17 +0200 (CEST) Date: Wed, 11 Oct 2023 09:33:17 +0200 From: Peter Zijlstra To: Abel Wu Cc: Benjamin Segall , mingo@kernel.org, vincent.guittot@linaro.org, linux-kernel@vger.kernel.org, juri.lelli@redhat.com, dietmar.eggemann@arm.com, rostedt@goodmis.org, mgorman@suse.de, bristot@redhat.com, corbet@lwn.net, qyousef@layalina.io, chris.hyser@oracle.com, patrick.bellasi@matbug.net, pjt@google.com, pavel@ucw.cz, qperret@google.com, tim.c.chen@linux.intel.com, joshdon@google.com, timj@gnu.org, kprateek.nayak@amd.com, yu.c.chen@intel.com, youssefesmat@chromium.org, joel@joelfernandes.org, efault@gmx.de, tglx@linutronix.de Subject: Re: Re: [PATCH 05/15] sched/fair: Implement an EEVDF like policy Message-ID: <20231011073317.GJ14330@noisy.programming.kicks-ass.net> References: <20230531115839.089944915@infradead.org> <20230531124603.931005524@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 11, 2023 at 12:14:30PM +0800, Abel Wu wrote: > With Benjamin's fix, the semantics of 'Earliest Eligible' preserved. Yeah, my bad. > But since all this is about latency rather than fairness, I wonder if It is about both, fairness is absolutely important. > there are cases worthy of breaking the 'eligible' rule. See the discussion with Youssef, if we weaken the eligible rule you get horrific interference because you end up placing new tasks around the 0-lag point.