RE: [EXTERNAL] Re: [PATCH v2 0/2] vhost-vdpa: Add support for NO-IOMMU mode

Srujana Challa
2024-10-17T08:53:24Z

> Subject: Re: [EXTERNAL] Re: [PATCH v2 0/2] vhost-vdpa: Add support for NO-
> IOMMU mode
>
> On Wed, Oct 16, 2024 at 05:28:27PM +0000, Srujana Challa wrote:
> > When using the DPDK virtio user PMD, we’ve noticed a significant 70%
> > performance improvement when IOMMU is disabled on specific low-end
> > x86 machines. This performance improvement can be particularly
> > advantageous for embedded platforms where applications operate in
> > controlled environments. Therefore, we believe supporting the
> > intel_iommu=off mode is beneficial.
>
> While making the system completely unsafe to use. Maybe you should fix
> your stack to use the iommu more itelligently instead?

We observed better performance with "intel_iommu=on" in high-end x86 machines,
indicating that the performance limitations are specific to low-end x86 hardware.
This presents a trade-off between performance and security. Since intel_iommu
is enabled by default, users who prioritize security over performance do not need to
disable this option.