Re: [PATCH 4/2] numa, mm: Rename the PROT_NONE fault handlingfunctions

From: Ingo Molnar
Date: Sun Oct 21 2012 - 09:43:57 EST



* Ingo Molnar <mingo@xxxxxxxxxx> wrote:

> > Michel indicated that he does not use PROT_NONE for his
> > working set estimation code, but instead checks the accessed
> > bits in the page tables.
>
> The pte_young() WSS method has a couple of fundamental
> limitations:
>
> - it doesn't work with shared memory very well, the pte is per
> mapping, not per page. The PROT_NONE method instruments the
> physical page in essence.
>
> - it does not tell us which task touched the pte, in a
> multi-threaded program
>
> So like Peter I'd too expect these new WSS methods to eventually
> be picked up for any serious WSS work.

Nevertheless lets wait and see until it actually happens - and
meanwhile the prot_none namings are confusing.

So I've applied your patch as-is, with two more (new) usage
sites converted as well. Will push it out after a bit of
testing.

Thanks,

Ingo
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