Re: [PATCH 22/35] autonuma: sched_set_autonuma_need_balance

[Peter Zijlstra]

On Tue, 2012-05-29 at 19:33 +0200, Andrea Arcangeli wrote:
> So the cost on a 24-way SMP 

is irrelevant.. also, not every cpu gets to the 24 cpu domain, just 2
do.

When you do for_each_cpu() think at least 4096, if you do
for_each_node() think at least 256.

Add to that the knowledge that doing 4096 remote memory accesses will
cost multiple jiffies, then realize you're wanting to do that with
preemption disabled.

That's just a very big no go.
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