Re: [PATCH 01/02] cpuset memory spread slab cache filesys

[Paul Jackson <pj@sgi.com>]

Andi wrote:
> The main reason i'm reluctant to use this is that the cpuset fast path
> overhead (e.g. in memory allocators etc.) is quite large

I disagree.

I spent much time minimizing that overhead over the last few months, as
a direct result of your recommendation to do so.

Especially in the case that all tasks are in the root cpuset (as in the
scenario I just suggested for setting this memory spreading policy for
all tasks), the overhead is practically zero.  The key hook is an
inline test done (usually) once per page allocation on an essentially
read only global 'number_of_cpusets' that determines it is <= 1.

I disagree with your "quite large" characterization.

Please explain further.

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                  Paul Jackson <pj@sgi.com> 1.925.600.0401