Re: [PATCH] Document Linux Memory Policy

[Christoph Lameter <clameter@sgi.com>]

On Thu, 31 May 2007, Gleb Natapov wrote:

> > The faulted page will use the memory policy of the task that faulted it 
> > in. If that process has numa_set_localalloc() set then the page will be 
> > located as closely as possible to the allocating thread.
> 
> Thanks. But I have to say this feels very unnatural. So to have
> desirable effect I have to create shared memory with shmget?

Right. From a user perspective: How would you solve the problem that

1. A shared range has multiple tasks that can fault pages in.
   The policy of which task should control how the page is allocated?
   Is it the last one that set the policy?

2. Pagecache pages can be read and written by buffered I/O and
   via mmap. Should there be different allocation semantics
   depending on the way you got the page? Obviously no policy
   for a memory range can be applied to a page allocated via
   buffered I/O. Later it may be mapped via mmap but then
   we never use policies if the page is already in memory.

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