On Thu, Oct 17, 2024 at 4:53 PM Srujana Challa <schalla@xxxxxxxxxxx> wrote: > > > 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. Do you have any analysis on why Intel IOMMU is slow on "low-end" x86 hardware? Anyhow, we can ask Intel IOMMU experts to help here. Thanks > 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.
