Re: [PATCH 0/7] Intel IOMMU scalability improvements

[Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>]

Hi Adam,

On Mon, Dec 28, 2015 at 06:14:21PM +0200, Adam Morrison wrote:
> This patchset improves the scalability of the Intel IOMMU code by
> resolving two spinlock bottlenecks, yielding up to ~10x performance
> improvement and approaching iommu=off performance.
> 
> For example, here's the throughput obtained by 16 memcached instances
> running on a 16-core Sandy Bridge system, accessed using memslap on
> another machine that has iommu=off, using the default memslap config
> (64-byte keys, 1024-byte values, and 10%/90% SET/GET ops):
> 
>     stock iommu=off:
>        1,088,996 memcached transactions/sec (=100%, median of 10 runs).
>     stock iommu=on:
>        123,760 memcached transactions/sec (=11%).
>        [perf: 43.56%    0.86%  memcached       [kernel.kallsyms]      [k] _raw_spin_lock_irqsave]
>     patched iommu=on:
>        1,067,586 memcached transactions/sec (=98%).
>        [perf: 0.75%     0.75%  memcached       [kernel.kallsyms]      [k] _raw_spin_lock_irqsave]
>

Thanks for the patches, the results look pretty impressive. I'll have a
closer look at your changes this week.



	Joerg