From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f175.google.com (mail-pf1-f175.google.com [209.85.210.175]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2E7326F31E for ; Thu, 30 May 2024 23:38:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.175 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717112332; cv=none; b=kc7YWf7RDYueT3dC9CxdPYt3pTNPSyccHqm+giGZYM0TqmLDivM5vYppcneJz77oQJdoBmFe3QwoDygK8sRWODSEdN8BYQw6PU2NnehbkDuWPuA3onrFdmoWpsWOgVolV9SURiNgOtnv/jHDQEmsiaf94QPK6FkIYHc425E+z/8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717112332; c=relaxed/simple; bh=QUJSuy03ZNCBmwqJCUsiWVC2HAXMATM6ee7y40cP49E=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=rgH2Jpz0Su5TLfmJsw3nz8XrpGPx0DlHPIXKoYr5+8XwRAwdHOZTkQd9qmKGIs6FMXW4mkOW0fbwGrGGIIv0uxn0SlsBWyglOvlA7seINNhq/G8keP5wqNG6vbf0eV52t55Lu2elJpaz+ZWeAsT/SVV5rhZrwSSclbNG3s8N2hI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.dk; spf=pass smtp.mailfrom=kernel.dk; dkim=pass (2048-bit key) header.d=kernel-dk.20230601.gappssmtp.com header.i=@kernel-dk.20230601.gappssmtp.com header.b=wvtZDYTb; arc=none smtp.client-ip=209.85.210.175 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.dk Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=kernel.dk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20230601.gappssmtp.com header.i=@kernel-dk.20230601.gappssmtp.com header.b="wvtZDYTb" Received: by mail-pf1-f175.google.com with SMTP id d2e1a72fcca58-6f8e818d96eso142543b3a.0 for ; Thu, 30 May 2024 16:38:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20230601.gappssmtp.com; s=20230601; t=1717112327; x=1717717127; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=azpfnJm0mug0EVvJB8AQ1srTjfoaqaqJ3tahTbkkpDE=; b=wvtZDYTbL6CojmshSbpr6LXZJeiQFQmj7RqJAAgc/DHR/TFC1T1DvTAMrLKPRrlKzy EIhm+1M8tvap2VsCRBEszh/0Ax0f2DAiqAGBF86NR+a8m36cRXqjhwsP6JL5IIeEtW6K z8FYlYyxTUeoEEkJLSyJfmzjOfvoHveLKaSDiI7G6oBOl60Tws5AxB2TKNjwLbyOusk5 4/kKaq1NJUmbm3Cs4sebh2X26+WaJC+AcXrB6SHL55fYRtNzDzHcbFjubKWillSmLX4X suLYlw6j4dvbozMgQJ14qfDtA/U86KsJnaz775vd15I9K1gBdNgXq/D8QYyetdS3ygYm l66g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1717112327; x=1717717127; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=azpfnJm0mug0EVvJB8AQ1srTjfoaqaqJ3tahTbkkpDE=; b=SlSzBG6FlEs2L3qAzlqC+4bRaxTITiVtYnCgN5vT2vc05YhU5EL3XKhPplCGaY8ink 3XjNo7saHQoM2QaCbKA0AQm70O0kpeOCczYPRToNYc6X7CQkQYU7DKYFfbWQYYbg77jN nIftT3gwh5vZQxlNbPdk7I/DDZUtZH50Hz1uMfN0uhkOamMdojiANhXlppm9UvbVikE8 A+3SZkHwUeTN90kjKOXe9LI837+HEzpZFk8qhZojF7WDAhUQ7leiEEm77H3IapBOEiOM 2+laIcMk6mgqhkkoqbWxzvo+Hc989j+GLZDJ+I0deHySjO0jr09gYg0bmKZ4BPsyKxmU lsDg== X-Gm-Message-State: AOJu0YzRYSYe+hOjB2OjhSv+kxN/12zETfZ+3+O10bNuyO9IT6CqR1TA 3j/1vxfkVq+IiA1O8wtyPgIMTiBv0ct9zQF8N/bOIxcCBROHRKREtX8bMM1pkG8= X-Google-Smtp-Source: AGHT+IFKTaIPWnYyei/5f5JIhUPPRBKl9ci5wgcU4MsOZw89htXm+bNFXqSj2haXAanHAvF0qe2dHA== X-Received: by 2002:a05:6a00:8b18:b0:6f8:582e:6edf with SMTP id d2e1a72fcca58-702477bd88cmr317811b3a.1.1717112327061; Thu, 30 May 2024 16:38:47 -0700 (PDT) Received: from [192.168.1.150] ([198.8.77.157]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7024967ae05sm13924b3a.157.2024.05.30.16.38.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 30 May 2024 16:38:45 -0700 (PDT) Message-ID: <7a69eba2-42e4-4c67-8a54-37b5b41675f9@kernel.dk> Date: Thu, 30 May 2024 17:38:44 -0600 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7] block: Improve IOPS by removing the fairness code To: Keith Busch , Bart Van Assche Cc: linux-block@vger.kernel.org, Christoph Hellwig , Hannes Reinecke , Ming Lei , Yu Kuai References: <20240529213921.3166462-1-bvanassche@acm.org> Content-Language: en-US From: Jens Axboe In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/30/24 3:17 PM, Keith Busch wrote: > On Thu, May 30, 2024 at 02:02:20PM -0700, Bart Van Assche wrote: >> Thank you for having run this test. I propose that users who want better >> fairness than what my patch supports use an appropriate mechanism for >> improving fairness (e.g. blk-iocost or blk-iolat). This leaves the choice >> between maximum performance and maximum fairness to the user. Does this >> sound good to you? > > I really don't know, I generally test with low latency devices and > disable those blk services because their overhead is too high. I'm > probably not the target demographic for those mechanisms. :) Yeah same. But outside of that, needing to configure something else is also a bit of a cop out. From the initial posting, it's quoting 2.9% gain. For lots of cases, adding blk-iocost or blk-iolat would be MORE than a 2.9% hit. That said, I'd love to kill the code, but I still don't think we have good numbers on it. Are yours fully stable? What does the qd=1 test do _without_ having anyone compete with it? Is the bandwidth nicely balanced if each does qd=32? I'm again kindly asking for some testing :-) > I just wanted to push the edge cases to see where things diverge. > Perhaps Jens can weigh in on the impact and suggested remedies? Don't think we have enough data yet to make the call... -- Jens Axboe