Re: [PATCH 0/2] mm: memory policy for page cache allocation

[Andi Kleen <ak@suse.de>]

> (1)  We dropped the MPOL_ROUNDROBIN patch.  Instead, we
>      use MPOL_INTERLEAVE to spread pages across nodes.
>      However, rather than use the file offset etc to 
>      calculate the node to allocate the page on, I used
>      the same mechanism you used in alloc_pages_current()
>      to calculate the node number (interleave_node()).
>      That eliminates the need to generate an offset etc
>      in the routines that call page_cache_alloc() and to
>      me appears to be a simpler change that still fits
>      within your design.


Hmm, that may lead to uneven balancing because the counter is 
per thread. But if it works for you it's ok I guess.

I still think changing the callers and use the offset for
static interleaving would be better. Maybe that could be
done as a followon patch. 
> 
> (2)  I implemented the sys_set_mempolicy() changes as
>      suggested -- higher order bits in the mode (first)
>      argument specify whether or not this request is for
>      the page allocation policy (your existing policy)
>      or for the page cache allocation policy.  Similarly,
>      a bit there indicates whether or not we want to set
>      the process level policy or the system level policy.
> 
>      These bits are to be set in the flags argument of
>      sys_mbind().

Ok.  If that gets in I would suggest you also document it 
in the manpages and send me a patch. 

Comments to the patches in other mail.

-Andi