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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT 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 BCF29C04EBF for ; Mon, 3 Dec 2018 18:25:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 92126208A3 for ; Mon, 3 Dec 2018 18:25:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 92126208A3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-block-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726937AbeLCSZR (ORCPT ); Mon, 3 Dec 2018 13:25:17 -0500 Received: from mga03.intel.com ([134.134.136.65]:47108 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726526AbeLCSZR (ORCPT ); Mon, 3 Dec 2018 13:25:17 -0500 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 03 Dec 2018 10:25:16 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,311,1539673200"; d="scan'208";a="115687380" Received: from unknown (HELO localhost.localdomain) ([10.232.112.69]) by FMSMGA003.fm.intel.com with ESMTP; 03 Dec 2018 10:25:16 -0800 Date: Mon, 3 Dec 2018 11:22:29 -0700 From: Keith Busch To: Christoph Hellwig Cc: Jens Axboe , Sagi Grimberg , Max Gurtovoy , "linux-nvme@lists.infradead.org" , "linux-block@vger.kernel.org" Subject: Re: [PATCH 10/13] nvme-mpath: remove I/O polling support Message-ID: <20181203182229.GG14775@localhost.localdomain> References: <20181202164628.1116-1-hch@lst.de> <20181202164628.1116-11-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181202164628.1116-11-hch@lst.de> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Sun, Dec 02, 2018 at 08:46:25AM -0800, Christoph Hellwig wrote: > The ->poll_fn has been stale for a while, as a lot of places check for mq > ops. But there is no real point in it anyway, as we don't even use > the multipath code for subsystems without multiple ports, which is usually > what we do high performance I/O to. If it really becomes an issue we > should rework the nvme code to also skip the multipath code for any > private namespace, even if that could mean some trouble when rescanning. > > Signed-off-by: Christoph Hellwig This was a bit flawed anyway since the head's current path could change, and you end up polling the wrong request_queue. Not really harmful other than some wasted CPU cycles, but might be worth thinking about if we want to bring mpath polling back. Reviewed-by: Keith Busch From mboxrd@z Thu Jan 1 00:00:00 1970 From: keith.busch@intel.com (Keith Busch) Date: Mon, 3 Dec 2018 11:22:29 -0700 Subject: [PATCH 10/13] nvme-mpath: remove I/O polling support In-Reply-To: <20181202164628.1116-11-hch@lst.de> References: <20181202164628.1116-1-hch@lst.de> <20181202164628.1116-11-hch@lst.de> Message-ID: <20181203182229.GG14775@localhost.localdomain> On Sun, Dec 02, 2018@08:46:25AM -0800, Christoph Hellwig wrote: > The ->poll_fn has been stale for a while, as a lot of places check for mq > ops. But there is no real point in it anyway, as we don't even use > the multipath code for subsystems without multiple ports, which is usually > what we do high performance I/O to. If it really becomes an issue we > should rework the nvme code to also skip the multipath code for any > private namespace, even if that could mean some trouble when rescanning. > > Signed-off-by: Christoph Hellwig This was a bit flawed anyway since the head's current path could change, and you end up polling the wrong request_queue. Not really harmful other than some wasted CPU cycles, but might be worth thinking about if we want to bring mpath polling back. Reviewed-by: Keith Busch