From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752534AbbJBQEn (ORCPT ); Fri, 2 Oct 2015 12:04:43 -0400 Received: from smtp02.citrix.com ([66.165.176.63]:17434 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752111AbbJBQEl (ORCPT ); Fri, 2 Oct 2015 12:04:41 -0400 X-IronPort-AV: E=Sophos;i="5.17,623,1437436800"; d="scan'208";a="307710860" Subject: Re: [PATCH v3 2/9] xen-block: add document for mutli hardware queues/rings To: Bob Liu , References: <1441456782-31318-1-git-send-email-bob.liu@oracle.com> <1441456782-31318-3-git-send-email-bob.liu@oracle.com> CC: , , , , , , , , , From: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= X-Enigmail-Draft-Status: N1110 Message-ID: <560EAB13.10305@citrix.com> Date: Fri, 2 Oct 2015 18:04:35 +0200 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <1441456782-31318-3-git-send-email-bob.liu@oracle.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-DLP: MIA1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org El 05/09/15 a les 14.39, Bob Liu ha escrit: > Document multi queues/rings of xen-block. > > Signed-off-by: Bob Liu As said by Konrad, you should send this against the Xen public headers also (or even before). I have a comment below. > --- > include/xen/interface/io/blkif.h | 32 ++++++++++++++++++++++++++++++++ > 1 file changed, 32 insertions(+) > > diff --git a/include/xen/interface/io/blkif.h b/include/xen/interface/io/blkif.h > index c33e1c4..b453b70 100644 > --- a/include/xen/interface/io/blkif.h > +++ b/include/xen/interface/io/blkif.h > @@ -28,6 +28,38 @@ typedef uint16_t blkif_vdev_t; > typedef uint64_t blkif_sector_t; > > /* > + * Multiple hardware queues/rings: > + * If supported, the backend will write the key "multi-queue-max-queues" to > + * the directory for that vbd, and set its value to the maximum supported > + * number of queues. > + * Frontends that are aware of this feature and wish to use it can write the > + * key "multi-queue-num-queues", set to the number they wish to use, which > + * must be greater than zero, and no more than the value reported by the backend > + * in "multi-queue-max-queues". > + * > + * For frontends requesting just one queue, the usual event-channel and > + * ring-ref keys are written as before, simplifying the backend processing > + * to avoid distinguishing between a frontend that doesn't understand the > + * multi-queue feature, and one that does, but requested only one queue. > + * > + * Frontends requesting two or more queues must not write the toplevel > + * event-channeland ring-ref keys, instead writing those keys under sub-keys > + * having the name "queue-N" where N is the integer ID of the queue/ring for > + * which those keys belong. Queues are indexed from zero. > + * For example, a frontend with two queues must write the following set of > + * queue-related keys: > + * > + * /local/domain/1/device/vbd/0/multi-queue-num-queues = "2" > + * /local/domain/1/device/vbd/0/queue-0 = "" > + * /local/domain/1/device/vbd/0/queue-0/ring-ref = "" > + * /local/domain/1/device/vbd/0/queue-0/event-channel = "" > + * /local/domain/1/device/vbd/0/queue-1 = "" > + * /local/domain/1/device/vbd/0/queue-1/ring-ref = "" > + * /local/domain/1/device/vbd/0/queue-1/event-channel = "" AFAICT, it's impossible by design to use multiple queues together with multipage rings, is that right? Roger.