Re: How can I optimize a process on a NUMA architecture(x86-64 specifically)?

[Martin J. Bligh]

>> Without these two things the kernel will 
>> just allocate on the currently running CPU whatever that may be when in
>> fact a preference must be given to a CPU at some point, hopefully early
>> on in the life of the process, in order to take advantage of NUMA.
> 
> The kernel does a pretty good job of keeping processes on the CPU they've been 
> running on, and thus they'll probably stay close to their memory.  But 
> without explicit pinning, there's no guarantee.

One thing I *do* want to do, is instead of explicit homenodes, is to take
into account the per-node RSS of processes when doing my migration decisions.
That gives us a kind of dynamic homenode. I have the per-node RSS code in
my tree already from someone (Matt?), but we haven't used it.  Of course,
this throws off the O(1)-ness of balancing decisions, but as long as we
cap the number we look at, and only do it for cross-node rebalance migrates
(we don't need it for exec), I really don't care ;-)

M.

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