On Tue, 2010-09-14 at 21:01 +0200, Michael S. Tsirkin wrote:

On Tue, Sep 14, 2010 at 11:49:03AM -0700, Shirley Ma wrote:

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On Tue, 2010-09-14 at 20:27 +0200, Michael S. Tsirkin wrote:

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As others said, the harder issues for TX are in determining that

it's

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safe
to unpin the memory, and how much memory is it safe to pin to

beging

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with.  For RX we have some more complexity.

I think unpin the memory is in kfree_skb() whenever the last

reference

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is gone for TX. What we discussed about here is when/how vhost get
notified to update ring buffer descriptors. Do I misunderstand

something

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here? 

Right, that's a better way to put it. 

That's how this macvtap patch did. For how much pinned pages,it is
limited by sk_wmem_alloc size in this patch.

thanks
Shirley