On 08/02/2010 07:25 PM, Shirley Ma wrote:
On Mon, 2010-08-02 at 19:11 +0300, Avi Kivity wrote:
I don't understand this. gup_fast() only calls gup() if the page is
swapped out or read-only.
Oh, I used the page as read-only on xmit path. Should I use write
instead?
No, for xmit getting the page as read only is fine.
I was inaccurate, gup_fast() performs as follows:
- if .write = 1, gup_fast() will be fast if the page is mapped and writeable
- if .write = 0, gup_fast() will be fast if the page is mapped
so, using .write = 0 for the xmit path will be faster in more cases than
.write = 1.
When are you seeing gup_fast() fall back to gup()? It should be at most
once per page (when a guest starts up none of its pages are mapped, it
faults them in on demand).
--
error compiling committee.c: too many arguments to function
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