Re: [PATCH mm] slab: implement bulking for SLAB allocator

Jesper Dangaard Brouer
2015-09-08T15:54:58Z

On Tue, 8 Sep 2015 10:22:32 -0500 (CDT)
Christoph Lameter <cl@linux.com> wrote:

> On Tue, 8 Sep 2015, Jesper Dangaard Brouer wrote:
>
> > Also notice how well bulking maintains the performance when the bulk
> > size increases (which is a soar spot for the slub allocator).
>
> Well you are not actually completing the free action in SLAB. This is
> simply queueing the item to be freed later. Also was this test done on a
> NUMA system? Alien caches at some point come into the picture.

This test was a single CPU benchmark with no congestion or concurrency.
But the code was compiled with CONFIG_NUMA=y.

I don't know the slAb code very well, but the kmem_cache_node->list_lock
looks like a scalability issue. I guess that is what you are referring
to ;-)

--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Sr. Network Kernel Developer at Red Hat
Author of http://www.iptv-analyzer.org
LinkedIn: http://www.linkedin.com/in/brouer