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 CBE60C432C0 for ; Tue, 3 Dec 2019 07:41:08 +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 803782068E for ; Tue, 3 Dec 2019 07:41:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="F7LoQ93G" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 803782068E 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=cc4Q7HMgFz4iH+L34vr7B0G4or6Vm7LhjLwsl57O4Zg=; b=F7LoQ93Gry7J3C XBQoBkp5N5QgEVtuFJtf1ubHILJXPSp+6YPdlrFuhqvz2AuHieUIS8FJ12KJKmZhyLroV70Fx1IyH RL7D0ODpufvZKVx/CHOfdogU6zDDHM8UBzZHcI7ViIqAbOVjL3aA8ue6gTmnix0K4rhcyKgVoktxh fqCJmLz9PPApmX+d0LJlyBpXL02Po7Sxfn/d78f6Y+mqw412yiCToJIdm+tbtKi3H2kltDXQwHkYR pfbGDfCqEw0/F7zcgM6GH71hPzhvX60c7Rm2zLyrYL2xT6iLw5nd1JstGbM99LSQyN1tMBdsLNnmw 4h/9YSqXe0CyKne4LJPQ==; 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 1ic2nx-00058Y-48; Tue, 03 Dec 2019 07:41:05 +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 1ic2nq-0004z8-FJ for linux-nvme@lists.infradead.org; Tue, 03 Dec 2019 07:40:59 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 2023C68BFE; Tue, 3 Dec 2019 08:40:56 +0100 (CET) Date: Tue, 3 Dec 2019 08:40:55 +0100 From: Christoph Hellwig To: Keith Busch Subject: Re: [PATCH 0/4] nvme: Threaded interrupt handling improvements Message-ID: <20191203074055.GC23881@lst.de> References: <20191127175824.1929-1-kbusch@kernel.org> <20191129094640.6fq6wcxmfi4fwnlw@linutronix.de> <20191129162719.GA47681@C02WT3WMHTD6.lpcnextlight.net> <20191129170545.axnykbrabigzcghs@linutronix.de> <20191130170222.GA5273@redsun51.ssa.fujisawa.hgst.com> <20191202170538.juq745vddzsouufb@linutronix.de> <20191202171239.GA8547@lst.de> <20191202180659.GB21650@redsun51.ssa.fujisawa.hgst.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20191202180659.GB21650@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-20191202_234058_676733_2BD77501 X-CRM114-Status: GOOD ( 13.83 ) 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, Sebastian Andrzej Siewior , linux-nvme@lists.infradead.org, ming.lei@redhat.com, helgaas@kernel.org, tglx@linutronix.de, 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 Tue, Dec 03, 2019 at 03:06:59AM +0900, Keith Busch wrote: > On Mon, Dec 02, 2019 at 06:12:39PM +0100, Christoph Hellwig wrote: > > That's why I had the previous idea of one irq thread per cpu that > > is assigned to the irq. We'd have to encode a relative index into > > the hardirq handler return value which we get from bits encoded in > > the NVMe command ID, but that should be doable. At that point we > > shouldn't need the cond_resched. I can try to hack that up, but > > I'm not an expert on the irq thread code. > > I'm curious how you intend to implement this. We can't have two threads > operating on the same CQ at the same time since they have to reap the > CQ sequentially, so the threads can't selectively choose which entries it > handles in a queue with mixed encoded CPUs. True. > Perhaps we can have just one completion thread call > smp_call_function_single_async() with the encoded CPU? Well, blk-mq can do just that for us from blk_mq_complete_request. > But sadly, I recall we've observed broken controllers break when a > command id exceeds the queue-depth, and encoding CPUs in the command id > would do that. Hardware ruins our purity... Sigh.. _______________________________________________ linux-nvme mailing list linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme