From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: [PATCH] vhost: get 2% performance improved by reducing spin_lock race in vhost_work_queue Date: Mon, 20 May 2013 11:38:10 +0800 Message-ID: <51999AA2.8070806@redhat.com> References: <5872DA217C2FF7488B20897D84F904E7338FD1E5@nkgeml511-mbx.china.huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "rusty@rustcorp.com.au" , "mst@redhat.com" , "dhowells@redhat.com" , "(kvm@vger.kernel.org)" , "(netdev@vger.kernel.org)" To: Qinchuanyu Return-path: Received: from mx1.redhat.com ([209.132.183.28]:12811 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755195Ab3ETDiY (ORCPT ); Sun, 19 May 2013 23:38:24 -0400 In-Reply-To: <5872DA217C2FF7488B20897D84F904E7338FD1E5@nkgeml511-mbx.china.huawei.com> Sender: netdev-owner@vger.kernel.org List-ID: On 05/20/2013 11:06 AM, Qinchuanyu wrote: > Right now the wake_up_process func is included in spin_lock/unlock, but it could be done outside the spin_lock. > I have test it with kernel 3.0.27 and guest suse11-sp2, it provide 2%-3% net performance improved. > > Signed-off-by: Chuanyu Qin Make sense to me but need generate a patch against net-next.git or vhost.git in git.kernel.org. Btw. How did you test this? Care to share the perf numbers? Thanks > mu > --- a/drivers/vhost/vhost.c 2013-05-20 10:36:30.000000000 +0800 > +++ b/drivers/vhost/vhost.c 2013-05-20 10:36:54.000000000 +0800 > @@ -144,9 +144,10 @@ > if (list_empty(&work->node)) { > list_add_tail(&work->node, &dev->work_list); > work->queue_seq++; > + spin_unlock_irqrestore(&dev->work_lock, flags); > wake_up_process(dev->worker); > - } > - spin_unlock_irqrestore(&dev->work_lock, flags); > + } else > + spin_unlock_irqrestore(&dev->work_lock, flags); > } > > void vhost_poll_queue(struct vhost_poll *poll) > -- > 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