Re: [PATCH] 2.5.21 Nonlinear CPU support

[Andrew Morton]

Rusty Russell wrote:
> 
> ...
> Let's not perpetuate the myth that everything in the kernel needs to
> be tuned to the last cycle at all costs, hm?

I was more concerned about the RAM use, actually.

This patch is an additional reason for CONFIG_NR_CPUS, but I've rather
gone cold on that idea because the "proper fix" is to make all those
huge per-cpu arrays dynamically allocated.   So you can run a 64p kernel
on 2p without losing hundreds of k of memory and kernel address space.

But it looks like all those dynamically-allocated structures would
have to be allocated out to NR_CPUS anyway, to support hotplug, yes?

In which case, CONFIG_NR_CPUS is the only way to get the memory
back...

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