From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7F2045339B for ; Mon, 29 Apr 2024 12:14:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714392883; cv=none; b=uRvt7yW5sdq9goT4ooPizmYdj+zeBn7F29MnX9FfyCRX86KSsgBXYcwVSsl0ZBu1cewTGchbFmuTslg2939tGxdmN+hsI6GNH5YACjE1t8d2/JSFuZwrV7bu06MUa9UwtlCuBxJAx7Cb5YP44SskbqoFjsfUnohEULRN/pawqQk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714392883; c=relaxed/simple; bh=yLLgddFnrnABDuUB1yafXOe/Yq+61keclmMBQTyIhC8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=s3tJCA3OXDzQlQUvgJ71PBYvG9x8EbPjSa3ZbH5LJJf2rE81S/xeq/L4kQprN/OT1TAUrbDvx7CyBdWCAMT1RQOpPZCASxJTyLDO/l8kbzSrp2ITdNt0te77v7R4XWul8Sm5COzeTooBdzuSAuHtIuO9s+G4IWOlxitfiopw7WI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=QZepAvlp; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="QZepAvlp" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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=wzYPAOrbwt9NNU8El6k7WjcaPrNWyuOOHBHcaFPGonE=; b=QZepAvlp1FgqH01EFFyfaCFKy/ D/4YX1CmaMinmno3O0yt/UPJam0mXK2BbDCxCmGj6YH8OjGnv678w/fZs9fw/0EzYfyJeLdJM2Zt+ YF20ndE3XVm4wWXvBT4cmGWgR/5AhwgT+lK1/mNSLazB7KJfeJR9hHsLdcb75GLoOf27ui7xhNtcY KRU+n9BE57XaPtvbfwz9O3jSBTAs9Soro3jyoAyfcQzi40I/KWNPDqUqMpxOX0yWL75Qw4cmkkLqg qPRmcSemxcI1I6a1qfmgGhGBpCy/V8OPtd3cfo99JS32mSXFycrGTpJZJCO4DMNAIbFnuqmsWRk62 H5DC5lHg==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.97.1 #2 (Red Hat Linux)) id 1s1Ptn-0000000GUUx-0Yq4; Mon, 29 Apr 2024 12:14:23 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id C1755300684; Mon, 29 Apr 2024 14:14:22 +0200 (CEST) Date: Mon, 29 Apr 2024 14:14:22 +0200 From: Peter Zijlstra To: Mike Galbraith Cc: K Prateek Nayak , mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, linux-kernel@vger.kernel.org, wuyun.abel@bytedance.com, tglx@linutronix.de, Chen Yu , Oliver Sang Subject: Re: [RFC][PATCH 08/10] sched/fair: Implement delayed dequeue Message-ID: <20240429121422.GU30852@noisy.programming.kicks-ass.net> References: <14330cf4-8d9e-1e55-7717-653b800e5cee@amd.com> <747627a1414f1f33d0c237f555494149d6937800.camel@gmx.de> <2b9f7617f2b2130bb6270504ec3858f15d463f1d.camel@gmx.de> <20240425112855.GF21980@noisy.programming.kicks-ass.net> <20240426105607.GK12673@noisy.programming.kicks-ass.net> <20240426111607.GL12673@noisy.programming.kicks-ass.net> <18f557cd69fc65f5b43daddd8ad3e43278dfa44e.camel@gmx.de> <8d2fd91db108428680cd4ed988b36cf3f579c5ec.camel@gmx.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Sun, Apr 28, 2024 at 06:32:49PM +0200, Mike Galbraith wrote: > On Sat, 2024-04-27 at 08:42 +0200, Mike Galbraith wrote: > > On Fri, 2024-04-26 at 18:03 +0200, Mike Galbraith wrote: > > > fwiw, tbench liked the previous version better. > > > > The culprit lies somewhere in the new PREEMPT_SHORT patch. > > > > Ah, moving the curr eligibility check into pick_curr() left an > ineligible curr to be seen/used further down in pick_eevdf(). > > found: > if (!best || (curr && entity_before(curr, best))) > best = curr; Hmm yes, over aggressive cleanup that. Let me try again. > Nit: PREEMPT_SHORT depending on RUN_TO_PARITY looks odd. The thinking was that without RUN_TO_PARITY we'll always do a full pick and it will always pick a (new) shorter deadline task over current. The PREEMPRT_SHORT thing really is an exception to avoid RUN_TO_PARITY from ruining latency game for short tasks.