From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 13517D5AE6C for ; Thu, 7 Nov 2024 07:09:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=9gyDtqFpMqqX3UIYtIZEx+faPMVvVGG/jXDeyIQhGRI=; b=s3VwDZYCnEjG77euHXr6tzHSqB xV128Pvks6wqrsbiKKX1upcXOXiSQnW10sa4bQMzn4OwoqMmtfVaE834ZStZ6qzoqzeWF75md5kTv A//23we9B4i92EWohYCtVTm/XEj2A3pdM8ZFp9CTQaK0KkisH9vDPwcwoW4XoYv/VndqAySQnv4aE asWJ2Nka17GOmwx398PH/Jvt+B0x5Sc8Lfhlt/UBs2XixArHeKqd4nZU4GiGgCIUj+FsY7Et9U6SJ MnYnqjBBrJnxa5XB2ixh0R1XjemW/uAwB3BGnk+2H07RHaKs+ycPdd5Ve2oSoj0Xy1/vI6jMn3n8i lPaYAtuQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1t8weI-00000005w0z-0VsH; Thu, 07 Nov 2024 07:09:46 +0000 Received: from out30-132.freemail.mail.aliyun.com ([115.124.30.132]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1t8weD-00000005w0I-47Iz for linux-nvme@lists.infradead.org; Thu, 07 Nov 2024 07:09:44 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1730963378; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=9gyDtqFpMqqX3UIYtIZEx+faPMVvVGG/jXDeyIQhGRI=; b=nF+JdVo1aoG8nz/i2YI+p7q5yOdD8HFjJEdB3pGj8JhYJq4LJUf5i+K8rrmrRXrVpgpcmlrrkg3MILUux8Xc2z5B1VEEREyX7msLbqgSunZnzVoqQMr54zP5GqaZKb32ddvjfcona2K+X4SkI5Ndht7mK8+2MBVq8Myy5lSIbTM= Received: from 30.178.82.60(mailfrom:kanie@linux.alibaba.com fp:SMTPD_---0WIug2Yf_1730963373 cluster:ay36) by smtp.aliyun-inc.com; Thu, 07 Nov 2024 15:09:34 +0800 Message-ID: <19cf3e11-83d4-4057-a643-e052bab7680a@linux.alibaba.com> Date: Thu, 7 Nov 2024 15:09:33 +0800 MIME-Version: 1.0 User-Agent: =?UTF-8?B?TW96aWxsYSBUaHVuZGVyYmlyZCDmtYvor5XniYg=?= Subject: Re: [PATCH v2] nvme-multipath: introduce service-time iopolicy To: Christoph Hellwig Cc: kbusch@kernel.org, axboe@kernel.dk, sagi@grimberg.me, kch@nvidia.com, linux-nvme@lists.infradead.org References: <20241107063249.101179-1-kanie@linux.alibaba.com> <20241107063907.GA3353@lst.de> From: Guixin Liu In-Reply-To: <20241107063907.GA3353@lst.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241106_230942_491431_22F9896F X-CRM114-Status: UNSURE ( 7.98 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org 在 2024/11/7 14:39, Christoph Hellwig 写道: > On Thu, Nov 07, 2024 at 02:32:49PM +0800, Guixin Liu wrote: >> The service-time policy can dispatch I/O to the path with the lowest >> total amount of currently processed I/O, ensuring that new I/O can be >> sent to less-loaded paths when some paths are overloaded, thereby >> achieving lower latency. > What is the exact use case for this? The commit log is unfortunately > very sparse. In scenarios with varying random I/O sizes, the different I/O sizes being processed on each path can lead to slower processing and higher latency on paths under heavy load. By distributing the I/O to other paths with lighter loads, the I/O can be processed more quickly. Sorry for the sparse commit log, I will send a v3 to expain detaily. > All these little policies add up, and we have absolutely > no documentation on them :( I'm glad to add a document to introduce all these nvme-multipath polices within v3 patchset. Best Regards, Guixin Liu