From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lei Li Subject: Re: [PATCH] vhost: get 2% performance improved by reducing spin_lock race in vhost_work_queue Date: Mon, 20 May 2013 12:15:58 +0800 Message-ID: <5199A37E.90401@gmail.com> References: <5872DA217C2FF7488B20897D84F904E7338FD1E5@nkgeml511-mbx.china.huawei.com> <51999AA2.8070806@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Jason Wang , "rusty@rustcorp.com.au" , "mst@redhat.com" , "dhowells@redhat.com" , "(kvm@vger.kernel.org)" , "(netdev@vger.kernel.org)" To: Qinchuanyu Return-path: In-Reply-To: <51999AA2.8070806@redhat.com> Sender: kvm-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 05/20/2013 11:38 AM, Jason Wang wrote: > 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? I wonder how did you get the performance improved number 2%? > > 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 > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >