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 6F428C10F29 for ; Tue, 17 Mar 2020 12:49:27 +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 3BEE2205ED for ; Tue, 17 Mar 2020 12:49:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="sG9cg+Kb" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3BEE2205ED 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=/RINMTE8deBtRCmI9v0cgTJrxuOSMpyYIc87xQ2WiBw=; b=sG9cg+KbulPPab 8TCKebgK7GqNlgIpCkPdj09GeidxQd0HQAxsCVd4pZTBXjljt7qY/FOF2u1Jxj1eR1RAy/PagEucb SqdJPHMY8UbWSP07UmLVcSACOYBCYiUEha0jfNijcMcOm+i/9nB1RwXaNSAenV0tdQHlWJ/3taE9Z pA/Ww/6aTSfHqQt8VrFq/VYM24zYpog/R8TAd32sg2+ZTBgc5udYmNXg4P1igRzV2Hl2Z3zV/L9sg 5CL79Cx7Nvk5FXzGALf+KO1Oy4Ho0ExNKcXtNXlCoA9MvJME8eBtVhgnADr9dSLQ2e2amHihUg0si mqh3/4JDlbnYZlvt8k6A==; 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 1jEBeu-0007J3-Nq; Tue, 17 Mar 2020 12:49:24 +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 1jEBes-0007Ij-M0 for linux-nvme@lists.infradead.org; Tue, 17 Mar 2020 12:49:23 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 3240568BFE; Tue, 17 Mar 2020 13:49:20 +0100 (CET) Date: Tue, 17 Mar 2020 13:49:19 +0100 From: Christoph Hellwig To: Hannes Reinecke Subject: Re: [PATCH] nvme: stop mad sqsize increasing and decreasing Message-ID: <20200317124919.GD12316@lst.de> References: <20200313124410.39193-1-hare@suse.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200313124410.39193-1-hare@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-20200317_054922_865874_19906870 X-CRM114-Status: GOOD ( 10.84 ) 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: linux-nvme@lists.infradead.org, Christoph Hellwig , Keith Busch , Sagi Grimberg 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, Mar 13, 2020 at 01:44:10PM +0100, Hannes Reinecke wrote: > The NVMe spec only states: > > "One slot in each queue is not available for use due to Head and > Tail entry pointer definition." > > It does not say that the actual queue size needs to decremented > by one, it just means that we'll have to leave one slot free. > So kill the mad decreasing and increasing of sqsize, leave it > at the specified size, and only decrement the tagset by one to > ensure we leave one slot free. Not sure what is mad here. All the *qsize values are 0s based values on the wire, so the on the wire value need to be one lower than the proper value. Maybe we need to0sb / from0sb helpers to document these annoying things a little better? (%#^#Y@$ NVMe designers for burdening us with this bullshit..) _______________________________________________ linux-nvme mailing list linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme