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 X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 36E72C432C0 for ; Fri, 29 Nov 2019 08:31:08 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 094F621736 for ; Fri, 29 Nov 2019 08:31:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="XqIoBHlQ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 094F621736 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=1/5yC353T/iF7pqSmVRMLxGgy5pNffFr0ddoZEhm2qM=; b=XqIoBHlQXz+qSM qAoiR3nJMr8O3t9RwxHt0KSkc9x7u2efaCa+T3Ng9nhGJYQ7Tdam2yk+mZbOZiQnBHTpKjDu0bd8N QQa+T8r586ds+k3xQT3zF1+Hzjr0MgfpAmQ0BF0j7q0Niiy5v7VPOps0nyw1Lyd3vCgv10VmE88l8 EIoTPdZzvHV95y98PFLOw97ib3vJ0hcrm7yus09Uhck+e7QuYnTsVQ5Y3XoZmDkl9/PUArQywrMgE X82n0KnaPf+J4Mp1M/nVjk024vP6JoPRMEH6bTBYGm4hKzEmj7++wJgyou8IFl9iOjAZ8XPL1tIEC LsEbYeCN7EX8KX+tLtLw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iabgA-0005Jq-CM; Fri, 29 Nov 2019 08:31:06 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1iabg7-0005JR-IT for linux-nvme@lists.infradead.org; Fri, 29 Nov 2019 08:31:04 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 5B9DF68AFE; Fri, 29 Nov 2019 09:30:59 +0100 (CET) Date: Fri, 29 Nov 2019 09:30:59 +0100 From: Christoph Hellwig To: Keith Busch Subject: Re: [PATCH 0/4] nvme: Threaded interrupt handling improvements Message-ID: <20191129083059.GA10032@lst.de> References: <20191127175824.1929-1-kbusch@kernel.org> <20191128075047.GC20659@lst.de> <20191128175904.GA3011@redsun51.ssa.fujisawa.hgst.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20191128175904.GA3011@redsun51.ssa.fujisawa.hgst.com> 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-20191129_003103_763437_EA84D14E X-CRM114-Status: UNSURE ( 8.62 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: sagi@grimberg.me, bigeasy@linutronix.de, linux-nvme@lists.infradead.org, ming.lei@redhat.com, helgaas@kernel.org, Christoph Hellwig Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Fri, Nov 29, 2019 at 02:59:04AM +0900, Keith Busch wrote: > On Thu, Nov 28, 2019 at 08:50:47AM +0100, Christoph Hellwig wrote: > > + if (to_pci_dev(nvmeq->dev->dev)->msix_enabled) > > + __pci_msix_desc_mask_irq(irq_get_msi_desc(irq), 1); > > + else > > + writel(1 << nvmeq->cq_vector, nvmeq->dev->bar + NVME_REG_INTMS); > > Oh, we know which branch this would take before we register the callback, > so smaller specialized functions don't need if/else checks. I even want > to remove the shadow doorbell checks for normal devices by giving each > different submission/completion callbacks too. They are individually > unmeasurable, but maybe they'll add up! :D This branch is perfect fodder for the branch predictor. I see aboslutely no reason to osbfucate the code to get rid of it. We also actually remove more branches than that by open coding nvme_irq for the threaded irq case than are added here. _______________________________________________ linux-nvme mailing list linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme