Re: [PATCH -mm] vmscan: make mapped executable pages the first class citizen

Wu Fengguang
2009-05-12T04:35:54Z

On Tue, May 12, 2009 at 10:50:58AM +0800, Wu Fengguang wrote:
> > Now. How do we know that this patch improves Linux?
>
> Hmm, it seems hard to get measurable performance numbers.
>
> But we know that the running executable code is precious and shall be
> protected, and the patch protects them in this way:
>
> before patch: will be reclaimed if not referenced in I
> after patch: will be reclaimed if not referenced in I+A

s/will/may/, to be more exact.

> where
> A = time to fully scan the active file LRU
> I = time to fully scan the inactive file LRU
>
> Note that normally A >> I.
>
> Therefore this patch greatly prolongs the in-cache time of executable code,
> when there are moderate memory pressures.

Thanks,
Fengguang