Re: [PATCH 00/13] KVM: MMU: fast page fault

Avi Kivity
2012-04-17T12:42:02Z

On 04/17/2012 03:37 PM, Takuya Yoshikawa wrote:
> On Tue, 17 Apr 2012 10:51:40 +0300
> Avi Kivity <avi@redhat.com> wrote:
>
> > That's true with the write protect everything approach we use now. But
> > it's not true with range-based write protection, where you issue
> > GET_DIRTY_LOG on a range of pages and only need to re-write-protect them.
> >
> > (the motivation for that is to decrease the time between GET_DIRTY_LOG
> > and sending the page; as the time increases, the chances that the page
> > got re-dirtied go up).
>
> Thank you for explaining this.
>
> I was planning to give the userspace more freedom.
>
> Since there are many known algorithms to predict hot memory pages,
> the userspace will be able to tune the frequency of GET_DIRTY_LOG for such
> parts not to get too many faults repeatedly, if we can restrict the range
> of pages to protect.
>
> This is the fine-grained control.

Do you want per-page control, or just range-based?

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