Re: [patch] generic-ipi: remove kmalloc, cleanup

Rusty Russell
2009-02-16T07:17:03Z

On Saturday 14 February 2009 10:18:05 Peter Zijlstra wrote:
> On Sat, 2009-02-14 at 07:46 +1030, Rusty Russell wrote:
> > I'd be fascinated to see perf numbers once you kill the kmalloc. Because
> > this patch will add num_possible_cpus * NR_CPUS/8 bytes to the kernel which
> > is something we're trying to avoid unless necessary.
>
> You're free to make it a pointer and do node affine allocations from an
> init section of choice and add a hotplug handler.
>
> But I'm not quite sure how perf is affected by size overhead on
> ridiculous configs.

No, I meant "can you actually measure the perf win of this patch?". If you
did so, I missed it?

But if this patch is worthwhile, the right way to do this is make it a
cpumask_var_t, and do the alloc_cpumask_var_node() in that init routine.

Thanks,
Rusty.