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 02D7E3D4123 for ; Wed, 4 Feb 2026 14:06:13 +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=1770213975; cv=none; b=lv/EjUtnmeKE0ArNYPBnURT2JlakXdlAGxrwuFDhJwNbFDuLihv5KeB1ms01NtbfH7yxhkmg7aoWaFGtcBiShsrhk3j4/lvMQkheFkNsSC8m0oKtHHDSDBrt9KRMwHY5EARmVCecacp7EgV+zC4+X/dQtfqpOMmLMnTr/+4Fzzg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770213975; c=relaxed/simple; bh=J0oaIO4RYuSlMorqKSEbFtGmTbb9Y74ZI7TiAsZxifY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=S0gDrxL5a80FniEYxtcIx2937gSFi6IEXZLidTxJvbxqZdDt1V0N8gRN98usvBclIGNO/kPt2hTbuSjjzyk4YW0X7tJjDg4ZhMyOV7X6xbQWCxskUMiM/SBgZIJS9owgG8OXOdMQxTdWfbp9mE0Nr0NauHHW4iAngJPJuM2+gV4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (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=qk0LCFJ9; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (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="qk0LCFJ9" 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=CxuDqc/d57ai8k04Ecxw2XgR47a/q7YmNUAESDMXg4A=; b=qk0LCFJ9dr1doNoWBJhbRHtURN gWjw4nWiq7BEW8F/LLStpFw2QHRMNaD+3R/Dngy0InChyD2VCmyleQUgZQDnywoHT4aqSrzZ9wIWS PfZLKxRGG5r1+9EOTEr62QaRyt+o8tv3lH9lvMYmPeqXKGshsvBmzLHLeZGbT/UAd8bVfOP1cqV+e bo2YMds70z/2S0RAhLIXFxMk/DlOoQrRu40K8sZwynveDo21TCt1OHcufI0j6BDafdO82MPKMmFBa d8OwX4opZfM2p3WfX9VD6ABKaHYQ7bL1rhsrdKn+G4CZ9tGTIRbyfVWG4Pwi8TRKe3bJua45tKJ9N 2Lho9i4Q==; Received: from 2001-1c00-8d85-5700-266e-96ff-fe07-7dcc.cable.dynamic.v6.ziggo.nl ([2001:1c00:8d85:5700:266e:96ff:fe07:7dcc] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1vndVx-00000000d8w-1iMQ; Wed, 04 Feb 2026 14:05:54 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id ED11B300F1D; Wed, 04 Feb 2026 15:05:52 +0100 (CET) Date: Wed, 4 Feb 2026 15:05:52 +0100 From: Peter Zijlstra To: "Mohamed Abuelfotoh, Hazem" Cc: Mario Roy , Chris Mason , Joseph Salisbury , Adam Li , Josh Don , 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 Subject: Re: [PATCH 4/4] sched/fair: Proportional newidle balance Message-ID: <20260204140552.GF3016024@noisy.programming.kicks-ass.net> References: <3ef2a178-db96-4a2c-9e74-44ba81bef030@amazon.com> <20260127084412.GV171111@noisy.programming.kicks-ass.net> <20260129091937.GY166857@noisy.programming.kicks-ass.net> <683b4860-1076-43b8-8fb9-ca8ac26cd8f4@amazon.com> <20260202105144.GC1282955@noisy.programming.kicks-ass.net> <6237f4ee-6b07-4d79-8ee7-04e49a4e99b7@amazon.com> <20260204132710.GK2995752@noisy.programming.kicks-ass.net> 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 Wed, Feb 04, 2026 at 01:59:24PM +0000, Mohamed Abuelfotoh, Hazem wrote: > On 04/02/2026 13:27, Peter Zijlstra wrote: > > CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe. > > > > > > > > On Wed, Feb 04, 2026 at 12:45:41PM +0000, Mohamed Abuelfotoh, Hazem wrote: > > > > > Version | Benchmark name | SUT EC2 Instance| diff % > > > v6.12.66 | postgresql | c7a.4xlarge | -4.0% > > > v6.12.66 | nginx_lb | c7a.4xlarge | -5.0% > > > v6.12.66 | memcached | c7a.4xlarge | -11.0% > > > v6.12.66_proposed | postgresql | c7a.4xlarge | -4.0% > > > v6.12.66_proposed | nginx_lb | c7a.4xlarge | -5.0% > > > v6.12.66_proposed | memcached | c7a.4xlarge | -13.0% > > > > *sigh*, that actually made it worse for memcached :/ I'm not familiar > > with the memcached benchmark, is this something I can run on a single > > machine, or does it require high speed networking and 2 machines? > > Yup that's true it's slightly worse on memcached with the proposed fix:( The > memcached benchmark is kind of multi-layer test where you need at at least 2 > client machines and 1 server machine and 1 machine as a test coordinator. > The server VM is able to achieve 12.5 Gbps of network bandwidth and the > client each one is able to achieve 30 Gbps so I think it will be tricky and > likely impossible to reproduce this on a single machine. Urgh, yeah, while I have multiple machines, not two of them are the same and I can only offer 1 Gbps of networking, that's not going to keep anything busy. > I will try to > come-up with standalone reproduction steps that can be used to investigate > this memcached regression. Meanwhile we will share the fio regression > reproduction steps that I mentioned in my previous update. This should be > much simpler in steps and can be done on a single machine. Thanks! I have a few machines with a 'spare' nvme drive to run things on, hopefully that is sufficient.