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

[Wu Fengguang <fengguang.wu@intel.com>]

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