I used a special tool, this tool can send and receive packets parallelly. I set the tool to use the same traffic load. then i use the tool to test different version of kvm. 2010/11/23 Huang, Zhiteng <zhiteng.huang@xxxxxxxxx>: > Hi Lidong, > > What do you mean by 'send the same traffic load between...' ? > > See if my understanding is correct: > You have two identical physical machines (CPU/Memory/NIC...), one(A) runs RHEL6 Beta2(2.6.32-60) and the other one (B) runs RHEL6 (2.6.32-71). > Each machine booted 5 identical VMs and then VMs on machine A (pool A) paired up with VMs on machine B (pool B). Sending packets between two VM pools yielded 20% utilization difference. > > Did you test bi-direction traffic, i.e. first pool A sends and pool B receives then vice versa? > > Regards, > > HUANG, Zhiteng > > > > -----Original Message----- > From: kvm-owner@xxxxxxxxxxxxxxx [mailto:kvm-owner@xxxxxxxxxxxxxxx] On Behalf Of lidong chen > Sent: Tuesday, November 23, 2010 10:14 AM > To: tj@xxxxxxxxxx; sri@xxxxxxxxxx; mst@xxxxxxxxxx; Avi Kivity; kvm@xxxxxxxxxxxxxxx > Subject: Performance test result between per-vhost kthread disable and enable > > I test the performance between per-vhost kthread disable and enable. > > Test method: > Send the same traffic load between per-vhost kthread disable and enable, and compare the cpu rate of host os. > I run five vm on kvm, each of them have five nic. > the vhost version which per-vhost kthread disable we used is rhel6 beta 2(2.6.32.60). > the vhost version which per-vhost kthread enable we used is rhel6 (2.6.32-71). > > Test result: > with per-vhost kthread disable, the cpu rate of host os is 110%. > with per-vhost kthread enable, the cpu rate of host os is 130%. > > In 2.6.32.60,the whole system only have a kthread. > [root@rhel6-kvm1 ~]# ps -ef | grep vhost > root 973 2 0 Nov22 ? 00:00:00 [vhost] > > In 2.6.32.71,the whole system have 25 kthread. > [root@kvm-4slot ~]# ps -ef | grep vhost- > root 12896 2 0 10:26 ? 00:00:00 [vhost-12842] > root 12897 2 0 10:26 ? 00:00:00 [vhost-12842] > root 12898 2 0 10:26 ? 00:00:00 [vhost-12842] > root 12899 2 0 10:26 ? 00:00:00 [vhost-12842] > root 12900 2 0 10:26 ? 00:00:00 [vhost-12842] > > root 13022 2 0 10:26 ? 00:00:00 [vhost-12981] > root 13023 2 0 10:26 ? 00:00:00 [vhost-12981] > root 13024 2 0 10:26 ? 00:00:00 [vhost-12981] > root 13025 2 0 10:26 ? 00:00:00 [vhost-12981] > root 13026 2 0 10:26 ? 00:00:00 [vhost-12981] > > root 13146 2 0 10:26 ? 00:00:00 [vhost-13088] > root 13147 2 0 10:26 ? 00:00:00 [vhost-13088] > root 13148 2 0 10:26 ? 00:00:00 [vhost-13088] > root 13149 2 0 10:26 ? 00:00:00 [vhost-13088] > root 13150 2 0 10:26 ? 00:00:00 [vhost-13088] > ... > > Code difference: > In 2.6.32.60,in function vhost_init, create the kthread for vhost. > vhost_workqueue = create_singlethread_workqueue("vhost"); > > In 2.6.32.71,in function vhost_dev_set_owner, create the kthread for each nic interface. > dev->wq = create_singlethread_workqueue(vhost_name); > > Conclusion: > with per-vhost kthread enable, the system can more throughput. > but deal the same traffic load with per-vhost kthread enable, it waste more cpu resource. > > In my application scene, the cpu resource is more important, and one kthread for deal with traffic load is enough. > > So i think we should add a param to control this. > for the CPU-bound system, this param disable per-vhost kthread. > for the I/O-bound system, this param enable per-vhost kthread. > the default value of this param is enable. > > If my opinion is right, i will give a patch for this. > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx 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@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
