Re: [NUMA] Display and modify the memory policy of a process through /proc/<pid>/numa_policy

[Andi Kleen <ak@suse.de>]

On Fri, Jul 15, 2005 at 03:30:40PM -0700, Christoph Lameter wrote:
> I cannot imagine that migrate pages make it into the kernel in its 
> current form. It combines multiple functionalities that need to be 
> separate (it does update the memory policy, clears the page cache, deals 
> with memory policy translations and then does heuristics to guess which 
> vma's to transfer) and then provides a complex function moving of pages 
> between groups of nodes.
> 
> Therefore:
> 
> 1. Updating the memory policy is something that can be useful in other 
>    settings as well so it need to be separate. The patch we are discussing

Not for external processes except in the narrow special case
of migrating everything. External processes shouldn' t
know about virtual addresses of other people.


> 3. Memory policy translations better be done in user space. The batch
>    scheduler /sysadmin knows which node has what pages so it can easily 
>    develop page movement scheme that is optimal for the process.

I don't think the existing policies are complex enough to make
this useful. The mapping for page migration for all of 
them is quite straight forward.


-Andi
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