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

[Christoph Lameter <clameter@engr.sgi.com>]

On Sat, 16 Jul 2005, Paul Jackson wrote:

> I'm missing something here.  Are you saying that just a change to
> libnuma would suffice to accomplish what you sought with this patch?

Its a quite significant change but yes of course you can do that if you 
really favor libnuma and IMHO want to make it difficult to maintain and to 
use.

> If that's the case, we don't need a kernel patch, right?

Sure.

> And despite Andi's urging us to only access these facilities via
> libnuma, there is no law to that affect that I know of.  At the least,
> you could present user level only code that accomplished the object
> of this patch set, with no kernel change.

Sure you can write a series of tools that accomplish the same.
 
> I don't think that is possible, short of gross hackery on /dev/mem.
> I think some sort of kernel change is required to enable one task to
> change the numa policy of another task.

Yes doing what I said to libnuma would require a significant rework of the 
APIs and the kernel libnuma stuff. Its easier to implement the whole thing 
using /proc, then no libraries would need to be modified, no tools need to 
be written. Just accept the patch that I posted, fix up whatever has to be 
fixed and we are done.


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