From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mout.gmx.net (mout.gmx.net [212.227.17.20]) (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 1AC7463D for ; Tue, 2 Jul 2024 05:08:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=212.227.17.20 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719896944; cv=none; b=s0Q1UByns5cyc+askAc0FjiU8r0yyUE/bqcM/d353nhWKy30N8eD2R+YqkCS6UxjSXZsk6SuEq7ll3HkEv+oQuNDP5cVqbXHXWCeNmfbw6YquNnTJDSS9Ted9vEwCCdmQ6dxFZ/KaAejTbjRkhNMVjlNMLxrU8jbzImBHmjNe8c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719896944; c=relaxed/simple; bh=UxVIG7dKLGkddBvGjq+qVPLrWDDwt88FhnbhsqxRO/8=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=ajom4BUdDE58OMdAIoVec1398ccCx8gdImX0AS4Xamj5EYu0ivyKX2HzyP7Z+jR9MrqJoJSNjNz+Q9asrxoWXgZfB8dEZ5SwaXHxSuiweMCYrZw79S/2NZKXhIwWyOhf8/wxSyzSZ2x/WhVT0ip7kD2DUChSNvnXqHe0eTT0sYM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=gmx.de; spf=pass smtp.mailfrom=gmx.de; dkim=pass (2048-bit key) header.d=gmx.de header.i=efault@gmx.de header.b=PQnu3d0J; arc=none smtp.client-ip=212.227.17.20 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=gmx.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmx.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmx.de header.i=efault@gmx.de header.b="PQnu3d0J" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmx.de; s=s31663417; t=1719896917; x=1720501717; i=efault@gmx.de; bh=Dr4VuhNCo1a2b+BLo4JUUQejGlUxDbSoGc8IXOsOmas=; h=X-UI-Sender-Class:Message-ID:Subject:From:To:Cc:Date:In-Reply-To: References:Content-Type:MIME-Version:Content-Transfer-Encoding:cc: content-transfer-encoding:content-type:date:from:message-id: mime-version:reply-to:subject:to; b=PQnu3d0J29PyvrWCY2CBR4+73Lzz0dyKYZLQnB/J42tBI+LlxSqQbway7kRXVOmT bSasuVSXzRddWFBAXWV7nu3m4p5l0MoHD3upFe21QfPJGUgjQmgou02FMzmh3LEIu b7obNhxVw7MP3fkzN0d9f8yRscA3OMU12ad8qQa9zpIaT0lhjU08Kr+BXEihzdy3F BusgqPH5vUB+ZrVMXJGKqx9IlWi5GgP64YVCKVrOSOkHS50b/kGGjuvtTgbiNQ4+u 1uK39Kz+AtoYdj/zvzPK/l2mFvPRLll3+ccUJBEKbK8585H2bfIwc8Y4WOpv9sMUE BCBgKAq5hL5OYu96XQ== X-UI-Sender-Class: 724b4f7f-cbec-4199-ad4e-598c01a50d3a Received: from homer.fritz.box ([185.146.49.228]) by mail.gmx.net (mrgmx104 [212.227.17.168]) with ESMTPSA (Nemesis) id 1MJmKX-1si5sK1idl-00IPLu; Tue, 02 Jul 2024 07:08:37 +0200 Message-ID: Subject: Re: [PATCH 1/2] sched/fair: Record the average duration of a task From: Mike Galbraith To: Chen Yu Cc: Peter Zijlstra , Ingo Molnar , Juri Lelli , Vincent Guittot , Tim Chen , Yujie Liu , K Prateek Nayak , "Gautham R . Shenoy" , Chen Yu , linux-kernel@vger.kernel.org, Raghavendra K T Date: Tue, 02 Jul 2024 07:08:35 +0200 In-Reply-To: References: <338ec61022d4b5242e4af6d156beac53f20eacf2.1719295669.git.yu.c.chen@intel.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.42.4 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:0RyB7P1u8hBAYeXlz6MejoVA52KoVEH+ChBq93juWFP+bmBoui/ IZkBpetKNvYCDZpjDVzsUevjW7LnuiBHyKVwzzCcSpOvWYEXBizasYexeUpRuTB56Qc+hjE fPnsJzCtkgkOApKiuPs84YERo8ijnxxXpZ5t+fVRMDaknu0s6X80raEQGv/rjivkLLZfuUx wWTUdeIcW6w4/FG29AmJw== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:zG3eWS3HmL0=;drbwvA4SLQw1b8XG0m1SAuOJTQ0 eX7pNPY1YjxcCDl4JzPQk+0vobnpWif/FFLttB4F8YAcCwAi6orMFu6UC3CGW27HU4myxuR3+ C31TVO6BVIRYJtcf1hkTUjuTeNOMcylPql5vCVNHnItS/RUp4p04odc8mcwZJ/qpXx8m1AgBr 0a/RrCFPeWgX5nHwONmfv8KHaTwYQBHw44zyOOVwwkjNmOHIKfHGeZgqkrQ04hPax377p0bsG BF2Y0ng+G/u8G8s42BDm8tlSDdwmL3ZDCidb3TavvuPDg5LLxmgM/EmWmUR+hzDaqNBSPagnY ItJu6fj/f6VLyhKtwoQmzwllWSEU7XSaYcUK/yKNtclZ7LfVFglFdo8QsfDbpQY8WHFJ6Z6+O 7GWu/f7IPYculRtDffORFFoUr5Z6O7ddXAwyygcZ316u7l9Kfg+X4ntarcCY2jCDexYgIs1+F 06EnkoLpqTS2/pdopEUlFQxVFg/4Kdp9JryaZrTReaNUt8UMsdQwos1apouTYrg2/MCOKft4B EigDm0uQI5Fuh7fjBi4TTg0gMfJkrVP7nQ1QK4WYcFFKeBpuAMOdyeCt3RtaTruJgyLsb31YI FsHJUiN1+r3Zv5ELXT5gBI3Mbq7Hd2yCY54tbmsQBrPXP+zk8oYBhFy2GAr4JW4IKGmdUQHhE ZJboGT/qY96JzGt5ko8sqil+4BCPgmPUlD8tVAONvJ/QShgXXSblhtNPoLa/9HVGwoFSzDDH7 KV2kUZXHE2HSsQ3QWEuVNxgKeIw+gpJHvPreq0pepd3cJ8/bWwCvhr3zvdV1v0o/pOg9Rb+xt DAdESdtawgliWaccExY1qy+T9ag8b4II5IHkV8pMEXnZQ= On Mon, 2024-07-01 at 22:57 +0800, Chen Yu wrote: > > Just take a look at the high speed ping-pong thing (not a benchmark, > > that's a box full of tape measures, rather silly, but..).=C2=A0 TCP_RR= IS > > 1:1, has as short a duration as network stack plus scheduler can > > possibly make it, and is nearly synchronous to boot, two halves of a > > whole, the ONLY thing you can certainly safely stack.. > > I agree, this is a limited scenario. > > > but a shared L2 box still takes a wee hit when you do so. > > According to a test conducted last month on a system with 500+ CPUs wher= e 4 CPUs > share the same L2 cache, around 20% improvement was noticed (though not = as much > as on the non-L2 shared platform). This dinky box doesn't have 500 cores, but it's.. aw, adorable :) rpi4:/root # ONLY=3DTCP_RR netperf.sh TCP_RR-1 unbound Avg: 31754 Sum: 31754 TCP_RR-1 stacked Avg: 26625 Sum: 26625 TCP_RR-1 cross-core Avg: 32325 Sum: 32325 rpi4:/root # tbench.sh 1 30 2>&1|grep Throughput Throughput 139.024 MB/sec 1 clients 1 procs max_latency=3D1.116 ms rpi4:/root # taskset -c 3 tbench.sh 1 30 2>&1|grep Throughput Throughput 116.765 MB/sec 1 clients 1 procs max_latency=3D0.340 ms rpi4:/root # This little box running its stock 6.6.33 distro kernel pulls out a cross-core win for both maximally synchronous TCP_RR and the a bit lesser so but still pretty close tbench. The numbers mean little though, one propagation speed is lovely, but were there more, I'd be as stuck with them as I am with rpi4's one-speed (all ahead slow) gearbox. -Mike