Re: [PATCH] kmalloc_percpu

[Andrew Morton]

Rusty Russell <[e-mail]> wrote:
>
> It's a tradeoff, but I think it's worth it for a kmalloc_percpu which
> is fast, space-efficient and numa-aware, since the code is needed
> anyway.

I don't beleive that kmalloc_percpu() itself needs to be fast, as you say.

The code is _not_ NUMA-aware.  Is it?

> How about a compromise like the following (scaled with mem)?
> Untested, but you get the idea...

> +	/* Plenty of memory?  1GB = 64k per-cpu. */
> +	pool_size = max(((long long)num_physpages << PAGE_SHIFT) / 16384,
> +			(long long)pool_size);

On 64GB 32-way that's 128MB of lowmem.  Unpopular.  I'd settle for a __setup
thingy here, and a printk when the memory runs out.

btw, what's wrong with leaving kmalloc_percpu() as-is, and only using this
allocator for DEFINE_PERCPU()?