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 1D4B8C27C53 for ; Wed, 19 Jun 2024 05:30:32 +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=PgVt82JE2OhYrFI+mqrNMIifmfvl9LmnhZsxX0zKZ4c=; b=EjcepHxLOA6ujsQEbSqVxTRUqH c2oFIwsgR4WdQ1opFYWwWsQaevw+0voQHqSFOS88gLmtOD9i4IF8dEcYgVHSJBKndqo9WCHysZWNl Vvn7x+fFojaqzDrujJkkmYaRvKG4SUmlJbo1Fs3ovhe5+oAgCPv+34WPTWZnE6kP3H7gjumSDNQQq ElmMQYY/dbdqY/f3YmRgq/1TG7WyiVhmsDlSe7ElaaX7UIqaZlc4riywUpp2VC2gFYzW9SkCCzClw DIDQZQh8ePPKQV+lWOewwlgrUG6MdLGqzKdBujgKJr4WZcQtKiHtz+WiMW63cwObXctW5Z0ErKGvj ETXRhwaw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sJntr-0000000HWJA-33k9; Wed, 19 Jun 2024 05:30:27 +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 1sJntn-0000000HWIO-0vj4 for linux-nvme@lists.infradead.org; Wed, 19 Jun 2024 05:30:24 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 1EBBD68B05; Wed, 19 Jun 2024 07:30:16 +0200 (CEST) Date: Wed, 19 Jun 2024 07:30:15 +0200 From: Christoph Hellwig To: Hannes Reinecke Cc: Christoph Hellwig , Sagi Grimberg , Keith Busch , linux-nvme@lists.infradead.org Subject: Re: [PATCH] nvme-tcp: align I/O cpu with blk-mq mapping Message-ID: <20240619053015.GB29159@lst.de> References: <20240618120345.64761-1-hare@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240618120345.64761-1-hare@kernel.org> 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-20240618_223023_431114_3B88F852 X-CRM114-Status: GOOD ( 15.00 ) 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 On Tue, Jun 18, 2024 at 02:03:45PM +0200, Hannes Reinecke wrote: > Add a new module parameter 'wq_affinity' to spread the I/O > over all cpus within the blk-mq hctx mapping for the queue. > This avoids bouncing I/O between cpus when we have less > hardware queues than cpus. What is the benefit when setting it? What is the downside? Why do you think it needs to be conditional? > + } > if (wq_unbound) > queue->io_cpu = WORK_CPU_UNBOUND; > + else if (wq_affinity) { Missing curly braces. But this also means the wq_unbound options is incompatible with your new one. > + } else > queue->io_cpu = cpumask_next_wrap(n - 1, cpu_online_mask, -1, false); Overly long line here.