Re: [RFC] x86/tboot: add an option to disable iommu force on

[Joerg Roedel]

Hi Shaohua,

On Tue, Mar 21, 2017 at 11:37:51AM -0700, Shaohua Li wrote:
> IOMMU harms performance signficantly when we run very fast networking
> workloads. This is a limitation in hardware based on our observation, so
> we'd like to disable the IOMMU force on, but we do want to use TBOOT and
> we can sacrifice the DMA security bought by IOMMU. I must admit I know
> nothing about TBOOT, but TBOOT guys (cc-ed) think not eabling IOMMU is
> totally ok.

Can you elaborate a bit more on the setup where the IOMMU still harms
network performance? With the recent scalability improvements I measured
only a minimal impact on 10GBit networking.



	Joerg