Messages in this thread | | | Date | Mon, 02 Aug 2010 19:11:41 +0300 | From | Avi Kivity <> | Subject | Re: [RFC PATCH v8 00/16] Provide a zero-copy method on KVM virtio-net. |
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On 08/02/2010 07:01 PM, Shirley Ma wrote: > Hello Avi, > > On Sun, 2010-08-01 at 11:18 +0300, Avi Kivity wrote: >> I don't understand. Under what conditions do you use >> get_user_pages() >> instead of get_user_pages_fast()? Why? > The code always calls get_user_pages_fast, however, the page will be > unpinned in skb_free if the same page is not used again for a new > buffer. The reason for unpin the page is we don't want to pin all of the > guest kernel memory(memory over commit).
That is fine.
> So get_user_pages_fast will > call slow path get_user_pages.
I don't understand this. gup_fast() only calls gup() if the page is swapped out or read-only.
> Your previous comment is suggesting to keep the page pinned for > get_user_pages_fast fast path? >
Right now I'm not sure I understand what's happening.
-- error compiling committee.c: too many arguments to function
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