Re: Got iperf regression while intel_iommu is on, how to cut thecost of cache flushing

[Eric Dumazet]

On Tue, 2013-11-12 at 09:03 +0800, Ethan Zhao wrote:
> Eric,
>     We have tested the performance with the TSO and TSQ patches
> merged, the result not good, even worse than kernel without those two
> patches. any idea ?
> 
> kernel   : 3.11.x with TSO & TSQ merged.  ( CONFIG_INTEL_IOMMU_DEFAULT_ON=y )
> Network Interface : eth4
> Network driver    : be2net
> 
> Average Bandwidth for :
>    1.tcp-unidirectional test    : 4385 Mbits/sec
>    2.tcp-unidirectional-parallel: 9383 Mbits/sec
>    3.tcp-bidirectonal test      : 2755 Mbits/sec
> 
> vs
> 
> kernel   :  3.11.x without TSO & TSQ patches.
> (CONFIG_INTEL_IOMMU_DEFAULT_ON is not set)
> Network Interface : eth4
> Network driver    : be2net
> 
> Average Bandwidth for :
>    1.tcp-unidirectional test    : 7992 Mbits/sec
>    2.tcp-unidirectional-parallel: 9403 Mbits/sec
>    3.tcp-bidirectonal test      : 5802 Mbits/sec
> 

So it seems its not the TSO/TSQ changes, but
CONFIG_INTEL_IOMMU_DEFAULT_ON being on instead of off.



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