From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Durrant Subject: RE: [PATCH 0/2] limit xen vnic max queues number to online cpu number Date: Fri, 23 Oct 2015 09:57:36 +0000 Message-ID: <9AAE0902D5BC7E449B7C8E4E778ABCD02F622669@AMSPEX01CL01.citrite.net> References: <5629E796.5040203@oracle.com> <9AAE0902D5BC7E449B7C8E4E778ABCD02F6220AF@AMSPEX01CL01.citrite.net> <5629F851.6010309@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Cc: "netdev@vger.kernel.org" , "xen-devel@lists.xenproject.org" To: Joe Jin , Wei Liu , Ian Campbell , Boris Ostrovsky , Konrad Rzeszutek Wilk , "David S. Miller" Return-path: Received: from smtp.ctxuk.citrix.com ([185.25.65.24]:60624 "EHLO SMTP.EU.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751113AbbJWJ5j convert rfc822-to-8bit (ORCPT ); Fri, 23 Oct 2015 05:57:39 -0400 In-Reply-To: <5629F851.6010309@oracle.com> Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: > -----Original Message----- > From: Joe Jin [mailto:joe.jin@oracle.com] > Sent: 23 October 2015 10:05 > To: Paul Durrant; Wei Liu; Ian Campbell; Boris Ostrovsky; Konrad Rzeszutek > Wilk; David S. Miller > Cc: netdev@vger.kernel.org; xen-devel@lists.xenproject.org > Subject: Re: [PATCH 0/2] limit xen vnic max queues number to online cpu > number > > On 10/23/2015 04:47 PM, Paul Durrant wrote: > >> -----Original Message----- > >> From: netdev-owner@vger.kernel.org [mailto:netdev- > >> owner@vger.kernel.org] On Behalf Of Joe Jin > >> Sent: 23 October 2015 08:54 > >> To: Wei Liu; Ian Campbell; Boris Ostrovsky; Konrad Rzeszutek Wilk; David > S. > >> Miller > >> Cc: netdev@vger.kernel.org; xen-devel@lists.xenproject.org > >> Subject: [PATCH 0/2] limit xen vnic max queues number to online cpu > >> number > >> > >> Currently xen vnic allowed to create lots of queues by set module param > >> max_queues(both netback and netfront), when queues number larger > than > >> cpu number, it does not help for performance but need more cpu time. > >> > > > > But it's an override, so why would you want to limit it? The parameter > should not be set in the common case. > > Always we can not stop people use it because we provided it :) > Indeed, and I believe it was provided largely for test purposes... to force the limit to whatever the admin wants. > If queues number is larger than cpu number, with heavy network load, > cpus have to take more time for interrupt, this lead others less > chance to be scheduled. > Imaging dom0 have 64 cpus, and assigned 4 vcpus to the guest, if > set max_queues to 64 on guest, it will consumed more cpu times > and bandwidth on backend, I think this is not we expected? > I think that would be entirely expected. Paul > Thanks, > Joe > > > > Paul > > > >> This patchset limit netback and netfront max queues number to online > >> cpus number. > >> > >> Joe Jin (2): > >> xen-netback: limit xen vif max queues number to online cpus > >> xen-front: limit vnic max_queues number to online cpus > >> > >> drivers/net/xen-netback/netback.c | 28 ++++++++++++++++++++++--- > --- > >> drivers/net/xen-netfront.c | 27 +++++++++++++++++++++------ > >> 2 files changed, 43 insertions(+), 12 deletions(-) > >> > >> -- > >> To unsubscribe from this list: send the line "unsubscribe netdev" in > >> the body of a message to majordomo@vger.kernel.org > >> More majordomo info at http://vger.kernel.org/majordomo-info.html