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 C8DD2C3814E for ; Fri, 5 Jul 2024 07:10:35 +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:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=w40R9PRvTa5t8bpf4mgimTEK+M64SuPcuHYzkz5oSW0=; b=gHcJblfDmekAPwQ1i41vT04ZDn qkJiGPaNcdPt9J5ThLEC/IV3Thdg9EJgp+VNZlVPJxLWlk53eoFm/6AKtNnj2dF0flhnFWJMi/9NH 8HQriUL98dG0//zkSWA9bv4u4Ip2ezfDLYwXlP3dAF094R+8ke+K+UV1BgJ3YK5aeLgAXLKPwUNWm /HorfLlfHVjUgPdGGf1aSTJ0X2c0gdBirDNMhupJnEOnktzNv0LscjrQ8zsey74SegMpnjyQvLMSI 197UkxtN/MeUx6DaS2x7Rbt7eXp+gbMYvuZ3Pl+2ccEx/xqKL6n9rWEh5OtmeG1Xx9+okG8EtYpGg zzAZMfAw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sPd5V-0000000F7EC-0JvF; Fri, 05 Jul 2024 07:10:33 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sPd5R-0000000F7Ds-3WVb for linux-nvme@lists.infradead.org; Fri, 05 Jul 2024 07:10:31 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 47F9268B05; Fri, 5 Jul 2024 09:10:23 +0200 (CEST) Date: Fri, 5 Jul 2024 09:10:22 +0200 From: Christoph Hellwig To: Hannes Reinecke Cc: Tejun Heo , Sagi Grimberg , Hannes Reinecke , Christoph Hellwig , Keith Busch , linux-nvme@lists.infradead.org Subject: Re: [PATCH 1/4] nvme-tcp: per-controller I/O workqueues Message-ID: <20240705071022.GA13302@lst.de> References: <20240703135021.34143-1-hare@kernel.org> <20240703135021.34143-2-hare@kernel.org> <7e4444d0-f156-439e-9363-4beb86bb6248@grimberg.me> <9de5d83c-4b05-4f69-8ab4-b4aa65e5ec62@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9de5d83c-4b05-4f69-8ab4-b4aa65e5ec62@suse.de> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240705_001030_044616_3E75DF82 X-CRM114-Status: GOOD ( 10.29 ) 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 Btw, I don't think brd is what we should optimize for. brd does synchronous I/O from ->submit_bio which makes it very non-typical. Trying to get this as good as possible for QD=1 might be fine, but once we have deeper queue depth and/or bigger I/O size it will use a lot more time in the submission context (aka the workqueues here) than a real device.