From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 9BB8519CC3D for ; Fri, 1 Nov 2024 12:57:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730465834; cv=none; b=QWcmJQdOCKHuZWGzu5xRaNNBKAcX6w6oHpd1exJpHNh1iQr8yE42hnSkNZdHwMM3iXedxah8vmnf30apzlHIdOM835SVG2RfHMKYLnFwEt2YeXIGqdCzsUy4KczKuqMznGSouGKCdf/YEg8UgAlkNPmzARs/Y+bfiQ50YTIpZls= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730465834; c=relaxed/simple; bh=1xgmAYR8gOJhNz5+vsmXGkOTW+5Z1pXG1kucwiBhuD4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=TSsYk7DoFGijNvXuY9sGkJLVJ4FueBkJIPAOMlDWx7MsOjT/flJBwcgTufXWy1jyn3ftiPHLFZfI70s/wdBxo85ylLZZ3KLBG+io5d1kax31Q+4F716c16orw+3Ty/W14VVoNTrdoDMbGy51uNM0IMq3Bz6iQXumLjTN4wA/dNg= 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=Gb/pO6j3; arc=none smtp.client-ip=90.155.50.34 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="Gb/pO6j3" 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=BJ3x7dwMTyYsrCAAfzTilxpM34ub+Eoo3YNGVgtXFQY=; b=Gb/pO6j3MgUp8mEYF9HNqPFBZ3 fRQQsJf2Fabt6+DCEMlC6gwedwNZC59R09aUrkOklddz1JmLR1bQ24v116sY2IB25bEKIIAJvxaeH IMz3i4yjG1XaeTLHIJQE4ijzfYFVTBnX4DhZHdPTbviKjf06KOichq5oPzY9Ka0fJw1mgmzkFXJp0 OQvJYEDN41GXUk7nlVHX9Dm+X98R1g9jxYdTOPL2MT7XufqDkx+QXfB6M7u1cVH7zD5lnvMmN4sK3 4nGQMGVGt2HlMNuop31Sg1oR6qhOJI+1Qb6PEJURgcGK1aW9OICkaMwaTikmVuKsxl6EJkCZNFg+h HtZ2OiVA==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1t6rD2-0000000FrQK-0jHJ; Fri, 01 Nov 2024 12:57:00 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id CB772300599; Fri, 1 Nov 2024 13:56:59 +0100 (CET) Date: Fri, 1 Nov 2024 13:56:59 +0100 From: Peter Zijlstra To: Phil Auld Cc: mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, linux-kernel@vger.kernel.org, kprateek.nayak@amd.com, wuyun.abel@bytedance.com, youssefesmat@chromium.org, tglx@linutronix.de, efault@gmx.de Subject: Re: [PATCH 17/24] sched/fair: Implement delayed dequeue Message-ID: <20241101125659.GY14555@noisy.programming.kicks-ass.net> References: <20240727102732.960974693@infradead.org> <20240727105030.226163742@infradead.org> <20241101124715.GA689589@pauld.westford.csb> 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: <20241101124715.GA689589@pauld.westford.csb> On Fri, Nov 01, 2024 at 08:47:15AM -0400, Phil Auld wrote: > This one is causing a 10-20% performance hit on our filesystem tests. > > On 6.12-rc5 (so with the latest follow ons) we get: > > with DELAY_DEQUEUE the bandwidth is 510 MB/s > with NO_DELAY_DEQUEUE the bandwidth is 590 MB/s > > The test is fio, something like this: > > taskset -c 1,2,3,4,5,6,7,8 fio --rw randwrite --bs 4k --runtime 1m --fsync 0 --iodepth 32 --direct 1 --ioengine libaio --numjobs 8 --size 30g --nrfiles 1 --loops 1 --name default --randrepeat 1 --time_based --group_reporting --directory /testfs > > In this case it's ext4, but I'm not sure it will be FS specific. > > I should have the machine and setup next week to poke further but I wanted > to mention it now just in case any one has an "aha" moment. > > It seems to only effect these FS loads. Other perf tests are not showing any > issues that I am aware of. There's a number of reports -- mostly it seems to be a case of excessive preemption hurting things. What happens if you use: schedtool -B -a 1-8 -e fio ....