Question about Virtual NIC I/O performance

Question about Virtual NIC I/O performance

[topperxin]

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Hi all
       Now I'm studying the Virtual NIC I/O performance, I have some questions
       1:
       For 1G NIC, such as Intel 82576, if I use pv driver as the VM NIC driver, for the best case, 
       I can get a good performance, maybe 900M bps
       So we can say the pv driver's performance is very good.
       While when I use 10G NIC, such as Intel 82599,  still use the pv driver as the VM NIC driver,
       the I/O performance is very bad, there is only 2G bps, the testing environment is simple, one vm on one host.
       So, may I draw a conclusion that PV driver not suitable for 10G NIC?
       Who can tell me the reason?
       2:
       For 10G NIC, Intel 82599, if I open the SR-IOV function, I can get a good performance in the vm, 
       it's nearly to 9.2G bps
       3:
       We all know AWS's EC2 instance are based on XEN.
       I launched the instance which provide the 10G performance I/O
       I tested and got the best performance the 6.3G bps
       I checked the driver of the VM's NIC, it's PV driver, not the SR-IOV
       How does AWS can use PV driver on 10G NIC get 6.3G bps performance? It's very good, I think


       Any discussion are welcome
       Best Regards
       Lixin Niu   

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Re: Question about Virtual NIC I/O performance

[Pasi Kärkkäinen]

On Thu, Nov 15, 2012 at 06:03:08PM +0800, topperxin wrote:
>    Hi all

Hello,

>           Now I'm studying the Virtual NIC I/O performance, I have some
>    questions
>           1:
>           For 1G NIC, such as Intel 82576, if I use pv driver as the VM NIC
>    driver, for the best case,
>           I can get a good performance, maybe 900M bps
>           So we can say the pv driver's performance is very good.
>           While when I use 10G NIC, such as Intel 82599,  still use the pv
>    driver as the VM NIC driver,
>           the I/O performance is very bad, there is only 2G bps, the testing
>    environment is simple, one vm on one host.
>           So, may I draw a conclusion that PV driver not suitable for 10G
>    NIC?
>

You didn't provide enough information..

What Xen version? What dom0 kernel version? What domU kernel version? 
What Intel NIC driver version? 

How did you configure/tune your system/settings? 


>           Who can tell me the reason! ?
>           2:
>           For 10G NIC, Intel 82599, if I open the SR-IOV function, I can get
>    a good performance in the vm,
>           it's nearly to 9.2G bps
>           3:
>           We all know AWS's EC2 instance are based on XEN.
>           I launched the instance which provide the 10G performance I/O
>           I tested and got the best performance the 6.3G bps
>           I checked the driver of the VM's NIC, it's PV driver, not the
>    SR-IOV
>           How does AWS can use PV driver on 10G NIC get 6.3G bps performance?
>    It's very good, I think
>

They've probably properly optimized and tuned the settings.


-- Pasi


>           Any discussion are welcome
>           Best Regards
>           Lixin Niu
>    </d! iv>

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