Re: [PATCH 1/5] cpuset memory spread basic implementation

[Ingo Molnar <mingo@elte.hu>]

* Paul Jackson <pj@sgi.com> wrote:

> It's job specific, and cache specific.
> 
> If the job has a number of threads hitting the same data set and:
>  1) the data set is faulted in non-uniformly (perhaps some
>     job init task reads it in), and
>  2) the data set is accessed with little thread locality
>     (one thread is as likely as the next to read or write
>     a particular page),
> then for that job spreading makes sense.
> 
> If the cache is one that goes with a data set, such as file system 
> buffers (page cache) and inode and dentry slab caches, then for that 
> cache spreading makes sense.  (Yes Andrew, your xfs query is still in 
> my queue.)
> 
> But for many (most?) other jobs and other caches, the default 
> node-local policy is better.

what type of objects need to be spread (currently)? It seems that your 
current focus is on filesystem related objects: pagecache, inodes, 
dentries - correct? Is there anything else that needs to be spread? In 
particular, does any userspace mapped memory need to be spread - or is 
it handled with other mechanisms?

	Ingo