Re: [PATCH net-next] net: allocate skbs on local node

Andrew Morton
2010-10-14T19:28:37Z

On Thu, 14 Oct 2010 08:31:01 -0700
Tom Herbert <therbert@google.com> wrote:

> > This is all conspicuously hand-wavy and unquantified. __(IOW: prove it!)
> >
> > The mooted effects should be tested for on both slab and slub, I
> > suggest. __They're pretty different beasts.
> > --
>
> Some results running netper TCP_RR test with 200 instances, 1 byte
> request and response on 16 core AMD using bnx2x with one 16 queues,
> one for each CPU.
>
> SLAB
>
> Without patch 553570 tps at 86% CPU
> With patch 791883 tps at 93% CPU
>
> SLUB
>
> Without patch 704879 tps at 95% CPU
> With patch 775278 tps at 92% CPU
>
> I believe both show good benfits with patch, and it actually looks
> like the impact is more pronounced for SLAB. I would also note, that
> we have actually already internally patched __netdev_alloc_skb to do
> local node allocation which we have been running in production for
> quite some time.
>

Yes, that's a solid gain.

Can we think of any hardware configuration for which the change would
be harmful? Something with really expensive cross-node DMA maybe?