Re: [PATCH] Use MPOL_PREFERRED for system default policy

[Lee Schermerhorn <Lee.Schermerhorn@hp.com>]

On Tue, 2007-08-14 at 12:51 -0700, Christoph Lameter wrote:
> On Tue, 14 Aug 2007, Lee Schermerhorn wrote:
> 
> > Now, system default policy, except during boot, is "local 
> > allocation".  By using the MPOL_PREFERRED mode with a negative
> > value of preferred node for system default policy, MPOL_DEFAULT
> > will never occur in the 'policy' member of a struct mempolicy.
> > Thus, we can remove all checks for MPOL_DEFAULT when converting
> > policy to a node id/zonelist in the allocation paths.
> 
> Isnt it possible to set a task policy or VMA policy to MPOL_DEFAULT 
> through the API? For the VMA policy this would mean fall back to task 
> policy. Is that still possible?

No.  mpol_new() returns NULL if policy==MPOL_DEFAULT, so you end up just
deleting any existing task policy and replacing it with a NULL pointer.
This is pretty cool, I think.  I have checked back, but Andi may have
done this from day 1.

Lee

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