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=-5.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 4C939C433DB for ; Sat, 6 Mar 2021 07:10:09 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 80C2B64FED for ; Sat, 6 Mar 2021 07:10:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 80C2B64FED 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=desiato.20200630; h=Sender:Content-Transfer-Encoding :Content-Type:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:Cc: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=jR15m8b8Bwxoy90eYXvEAd6FeSqbyRAZbhINjubYgOU=; b=pUKfwnBs7/fRP27I7OWEea8Qb M2sumA7Y1/3axvPwLedy+gGi3jYnOVcGwdW4mpNghNuF4hvMv4M7cLA0wi+8sryIa9sjgk4QACjRt +0miOZuhEl3I52rIUYMLUtKb4xmtX1KSGOUr4YMK6GUJQKZ71S4S4Rka5JSReOhDDWxOeFIsJzOUY VyEj8WpQnOYKh5yNgl926XSYZhAhyT1WoqlFeFSQhE6WRT9c/up430z+gNgeh5l9rRbbmnjOl1xe/ Zxz84nX6OjO1nCqyoz01HK6VE9Pvir0sRZUxj+gc5xIfa4kDNR5g8ZPQfQ0TzbVc4H8lUIJwkNNMd wiydHcL8Q==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lIR4T-001s4t-06; Sat, 06 Mar 2021 07:09:53 +0000 Received: from verein.lst.de ([213.95.11.211]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lIR4O-001s1q-K5 for linux-nvme@lists.infradead.org; Sat, 06 Mar 2021 07:09:50 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 5668B68B05; Sat, 6 Mar 2021 08:09:44 +0100 (CET) Date: Sat, 6 Mar 2021 08:09:44 +0100 From: Christoph Hellwig To: Sagi Grimberg Cc: Christoph Hellwig , Keith Busch , James Smart , linux-nvme@lists.infradead.org Subject: Re: [PATCH 1/3] nvme-fabrics: only reserve a single tag Message-ID: <20210306070944.GA28323@lst.de> References: <20210303125304.1200789-1-hch@lst.de> <20210303125304.1200789-2-hch@lst.de> <49d65274-002c-237b-163e-c3d482644a80@grimberg.me> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <49d65274-002c-237b-163e-c3d482644a80@grimberg.me> 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-20210306_070948_806369_7E350C7A X-CRM114-Status: GOOD ( 19.65 ) 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: , 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 05, 2021 at 12:51:15PM -0800, Sagi Grimberg wrote: > >> Fabrics drivers currently reserve two tags on the admin queue. But >> given that the connect command is only run on a freshly created queue >> or after all commands have been force aborted we only need to reserve >> a single tag. > > Umm, I think this would be an issue for non-mpath fabrics devices... > > When we teardown the controller, we iterate over all tags > and cancel them, however for non-mpath devices these actually > stick around until they exhaust the retrys counter (with the > hope that the controller will reconnect again) unlike the mpath > case where the requests are failed-over. > > Now if the admin queue is absolutely full during a reset, we won't > have a keep-alive command. > > One possible solution is to make sure that > nvme_decide_disposition to complete a request for admin > commands. However note that this means that admin commands > would fail immediately when the controller resets, which is > a regression from the existing behavior and we may piss off > users with that... We never retry admin commands! And the reserved tags are set aside and not relevant to the "normal" commands. _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme