Re: [PATCH v11 20/23] vfio: Add VFIO_DEVICE_[AT|DE]TACH_IOMMUFD_PT

Jason Gunthorpe
2023-06-06T14:46:29Z

On Thu, May 25, 2023 at 03:03:54AM +0000, Liu, Yi L wrote:

> vIOMMU may introduce some performance deduction if there
> are frequent map/unmap.

DPDK doesn't do that.

And once you turn on the HW IOMMU you negate alot of the micro
performance wins of bypassing. Maybe there is still some argument
about giant/huge pages or something.

> without vIOMMU is supposed to be more robust. But I'm not
> sure if the noiommu userspace will adapt to cdev noiommu.
> Perhaps yes if group may be deprecated in future.

I think that is more a distro question, and we don't have to answer it
fully now.

Jason