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

Takuya Yoshikawa
2012-04-17T12:37:55Z

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.

Thanks,
Takuya