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=-5.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham 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 64573C43603 for ; Tue, 10 Dec 2019 20:25:21 +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 36BF52073D for ; Tue, 10 Dec 2019 20:25:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="rdKWWagf"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="wubz8KRM" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 36BF52073D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org 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=aD2ta5+citT+6j3qksMV7Ho9stamWJ7KYGgF+4l/bNk=; b=rdKWWagf1H8ypg zL28AUbFGOZ1MznWB3oGYxAkVV/rxV2nmkOPJ1QQnPICFQjyjbscgbN9JlamA31FPyq5ViQ6MU6p5 hB2MDaP8vCy5/H0MIrBc9mlGgdOHp39oKPrYMvSceBAfIcOksIm4cAw9ccfCIKLd60huDIQzXd3MN ehvvdTbo7f/o9TPgSleMbF7G4eMT9WJT4bt4xKzI2q+1Uw70Apaw1u8U27TPF1sV4qnUjV3LuLgRR glnJ29VL8Y6Drgu3Ttak2DPLxmHMzlDT0CUPAaE7HZAuhHthtJsWcYEntKjyyxHpypGic1jNN650k qTFzM2mlTeSUPCDvDStQ==; 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 1iem4K-0006pg-Mk; Tue, 10 Dec 2019 20:25:16 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1iem4I-0006op-N9 for linux-nvme@lists.infradead.org; Tue, 10 Dec 2019 20:25:15 +0000 Received: from redsun51.ssa.fujisawa.hgst.com (unknown [199.255.47.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C555A20652; Tue, 10 Dec 2019 20:25:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576009513; bh=SUQ85xb1XOIniNeF8X5DL1svC3TrKcV45o9aw6jIMMk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=wubz8KRMnFBXFOC9cBapdMkNlfmn3nkVj3wg7M4JFTP1OyyPXuyQSAitFmjdjUvmX /DP3zHPxWhiK2EnpWQ9DEzofC+axGeKWSZHz5A0rdQJtLkeCm01fXKSuhBetn7RDdX 1LKLPed3Xo9bZCLfxp/sO1g05nmtIUwFsoUM0IVM= Date: Wed, 11 Dec 2019 05:25:06 +0900 From: Keith Busch To: Sagi Grimberg Subject: Re: [PATCHv3 2/4] nvme/pci: Complete commands from primary handler Message-ID: <20191210202506.GA26810@redsun51.ssa.fujisawa.hgst.com> References: <20191209175622.1964-1-kbusch@kernel.org> <20191209175622.1964-3-kbusch@kernel.org> <6d55a705-6a43-5b47-166c-5d2b458fd6a5@grimberg.me> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <6d55a705-6a43-5b47-166c-5d2b458fd6a5@grimberg.me> User-Agent: Mutt/1.12.1 (2019-06-15) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191210_122514_778511_A48F94F0 X-CRM114-Status: GOOD ( 12.62 ) 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: bigeasy@linutronix.de, hch@lst.de, tglx@linutronix.de, linux-nvme@lists.infradead.org, ming.lei@redhat.com 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 Tue, Dec 10, 2019 at 12:00:07PM -0800, Sagi Grimberg wrote: > > > diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c > > index a0138e3ca0b9..e415fadf7331 100644 > > --- a/drivers/nvme/host/pci.c > > +++ b/drivers/nvme/host/pci.c > > @@ -1055,6 +1055,10 @@ static irqreturn_t nvme_irq_check(int irq, void *data) > > if (!nvme_cqe_pending(nvmeq)) > > return IRQ_NONE; > > + nvme_irq(irq, data); > > + if (!nvme_cqe_pending(nvmeq)) > > + return IRQ_HANDLED; > > + > > Question Keith, > > If I have say 24 (or more) devices with a queue mapped to a cpu, and we > happen to just reap in the primary handler for all devices, all the time, > are we safe from cpu lockup? I can't readily test that scenario, but I'm skeptical a workload can keep the primary handler running without ever seeing it return IRQ_WAKE_THREAD. If that is really a problem, we can mitigate it by limiting the number of CQEs the primary handler may process. _______________________________________________ linux-nvme mailing list linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme