Re: Re: Re: Re: Re: [Xen-devel] SetPageForeign in netback

["Zang Hongyong" <zanghongyong@xxxxxxxxxx>]

Thanks a lot.
I noticed that the plug-in accelerator is available in Xen3.2 Source code. The 
accelerator is used for direct IO network devices such as Infiniband and 
Solarflare 10G Nic. 
Can it be used for the PCIE IOV devices? 
and is there any referece implementation of PCIE IOV Nics now?  

======= 2008-06-24 14:41:49 您在来信中写道：=======

>>>The reason why you have to copy is to make sure that you pull the skb
>>>into a fresh page (which doesn't have any other pieces of data in it).
>>>It's only then that you can flip it to DomU.
>>>It used to be the case that the backend was more efficient in the
>>>rx-flip mode. Some/most skbs copies were avoided by keeping a close
>>>eye on the skb allocation. Since rx-flip is now only/mostly kept for
>>>backward compatibility (rx-copy is the default) the code was
>>>simplified.
>>
>> You mean in previous Xen release, rx-flip is more efficient than today's 
>> release. And keeping rx-flip in Xen Source Code tree today is only for 
>> compatibility. So no need to do more optimizing for it.
>> Is my understanding right?
>>
>
>I don't know if much performance was lost (the code got simplified, at
>the expense of potentially more skb copies, but I don't know of any
>experimental tests to benchmark what the effect was exactly), but
>aside from that, your understanding is correct.
>
>Cheers
>Gr(z)egor(z)
>
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>

= = = = = = = = = = = = = = = = = = = =
Zang Hongyong
zanghongyong@xxxxxxxxxx
2008-06-25

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