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=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 BAF91C433E1 for ; Fri, 14 Aug 2020 06:57:19 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 871A920708 for ; Fri, 14 Aug 2020 06:57:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="lWyiInmf" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 871A920708 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=merlin.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=dw4QDO/HELL5co48yjQ3x40FiH0OrjDJZE4BNUA//zU=; b=lWyiInmfZXily0n1PX+nsgCVX 3qzHXDu4ne3eEtrZWa849jmtNW/C18nrrP5Bet//1z0iJi6TcNmnm6vc9bUSMjwQ0G9nXznkVjA+y 2gtjnZvUUkbnqQbHUGickS9MP0n36V6I41L5uKkNJewMUbL3jNHjLaZlHuZ7tYSlTpkSPgNPi87xG FnsZCWm8UG7DX61k9/CzXHl0WlcRKk05d7q1Lohr8dFxM/bC9+dQg06DuQkOz+IlCKDgH75oBUmJk 4rwRv2ygJYKSVIb3QaTX5AC7sE6evHrXW3ZCgQDnlAnPe1yYWZXjAYyB8iqYJFitrLxpHENkBMA2C aM/Wt4NdA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1k6TeP-00077f-IH; Fri, 14 Aug 2020 06:57:17 +0000 Received: from verein.lst.de ([213.95.11.211]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1k6TeM-000772-7Z for linux-nvme@lists.infradead.org; Fri, 14 Aug 2020 06:57:15 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id E4E5068CEE; Fri, 14 Aug 2020 08:57:11 +0200 (CEST) Date: Fri, 14 Aug 2020 08:57:11 +0200 From: Christoph Hellwig To: Sagi Grimberg Subject: Re: [PATVH V5] nvme-core: use xarray for ctrl ns tracking Message-ID: <20200814065711.GA2070@lst.de> References: <20200814021612.5161-1-chaitanya.kulkarni@wdc.com> <4654370f-40b9-1b35-1e22-864e762c3001@grimberg.me> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <4654370f-40b9-1b35-1e22-864e762c3001@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-20200814_025714_440400_DF02FAAD X-CRM114-Status: GOOD ( 15.36 ) 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: kbusch@kernel.org, linux-nvme@lists.infradead.org, hch@lst.de, Chaitanya Kulkarni 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 Thu, Aug 13, 2020 at 11:33:41PM -0700, Sagi Grimberg wrote: > >> This patch replaces the ctrl->namespaces tracking from linked list to >> xarray for better ns-mgmt on the host side. For host side >> nvme_find_get_ns() falls into the fast path for NVMeOF passthru target. >> This allows us to have better performance for NVMeOF passthru backend >> since XArray has shows better performance numbers over having >> a combination of read-write semapore read + linked list in the >> nvme_find_get_ns() to find namespace in I/O patch from nsid specified >> in the nvme_rw_cmd. > > This patch scares me to be honest... > > We have such non-trivial synchronization paths for ns scanning, ns > removal, quiescing, freezing, path handling... I'm not even sure > how many tests we'll need to verify that nothing breaks here. Yes, same concern here. That being said I have plans for this or next merge window to fix a lot of crap in the block layer about the bdev mutex to update the size, which should lead to major simpliciations of the nvme ns scanning/removal path. But I'd much rather sort that our first rather than touching this code now. _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme