From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752374AbbJGMUK (ORCPT ); Wed, 7 Oct 2015 08:20:10 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:47727 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751394AbbJGMUI (ORCPT ); Wed, 7 Oct 2015 08:20:08 -0400 Message-ID: <56150DCB.70705@oracle.com> Date: Wed, 07 Oct 2015 20:19:23 +0800 From: Bob Liu User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130308 Thunderbird/17.0.4 MIME-Version: 1.0 To: =?windows-1252?Q?Roger_Pau_Monn=E9?= CC: xen-devel@lists.xen.org, david.vrabel@citrix.com, linux-kernel@vger.kernel.org, konrad.wilk@oracle.com, felipe.franciosi@citrix.com, axboe@fb.com, hch@infradead.org, avanzini.arianna@gmail.com, rafal.mielniczuk@citrix.com, boris.ostrovsky@oracle.com, jonathan.davies@citrix.com Subject: Re: [PATCH v3 6/9] xen/blkfront: negotiate the number of hw queues/rings with backend References: <1441456782-31318-1-git-send-email-bob.liu@oracle.com> <1441456782-31318-7-git-send-email-bob.liu@oracle.com> <56128BC0.1090109@citrix.com> <5614F67C.3060003@oracle.com> <56150605.2090003@citrix.com> In-Reply-To: <56150605.2090003@citrix.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit X-Source-IP: aserv0022.oracle.com [141.146.126.234] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/07/2015 07:46 PM, Roger Pau Monné wrote: > El 07/10/15 a les 12.39, Bob Liu ha escrit: >> On 10/05/2015 10:40 PM, Roger Pau Monné wrote: >>> El 05/09/15 a les 14.39, Bob Liu ha escrit: >>>> @@ -2267,6 +2335,12 @@ static int __init xlblk_init(void) >>>> xen_blkif_max_ring_order = 0; >>>> } >>>> >>>> + if (xen_blkif_max_queues > nr_cpus) { >>> >>> Shouldn't there be a default value for xen_blkif_max_queues if the user >>> hasn't set the parameter on the command line? >>> >> >> Then the default value is 0, multi-queue isn't enabled by default. > > Why isn't it enabled by default with a sensible number of queues? I > guess something like: > > if (xen_blkif_max_queues == 0) > xen_blkif_max_queues = min(nr_cpus, 4); > I'm worry about complains about more memory consumption if set to 4 by default. Anyway, if you think it's fine I'll update the default value to 4 in next version. -- Regards, -Bob