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

[Peter Zijlstra]

On Thu, 2009-05-07 at 09:39 -0400, Christoph Lameter wrote:
> On Thu, 7 May 2009, Wu Fengguang wrote:
> 
> > Introduce AS_EXEC to mark executables and their linked libraries, and to
> > protect their referenced active pages from being deactivated.
> 
> 
> We already have support for mlock(). How is this an improvement? This is
> worse since the AS_EXEC pages stay on the active list and are continually
> rescanned.

It re-instates the young bit for PROT_EXEC pages, so that they will only
be paged when they are really cold, or there is severe pressure.

This simply gives them an edge over regular data. I don't think the
extra scanning is a problem, since you rarely have huge amounts of
executable pages around.

mlock()'ing all code just doesn't sound like a good alternative.
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