Re: [GIT PULL] core kernel update

From: Peter Zijlstra
Date: Tue Nov 19 2013 - 14:14:59 EST


On Tue, Nov 19, 2013 at 08:09:04PM +0100, Ingo Molnar wrote:
> The actual value of the limit - here's the on-stack cpumask sizes of
> the candidate range:
>
> 128 CPUs: 16 byte cpumasks
> 256 CPUs: 32 byte cpumasks
> 512 CPUs: 64 byte cpumasks

So 512 / 64bytes is a single cacheline and feels like a nice cut-off
before requiring an extra indirection and more cachelines.

64 bytes also doesn't sound _that_ big to have on-stack.

So I'd go for having the cut-off on >512, unless of course theres
evidence 64bytes is already too much.
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