Hi, Thank you for all the replies. I am trying to understand the impact of this on DPDK. What will be the repercussions of disabling "iommu=pt" on the DPDK performance?
On Tue, Oct 21, 2014 at 12:32 AM, Alex Markuze <alex at weka.io> wrote: > DPDK uses a 1:1 mapping and doesn't support IOMMU. IOMMU allows for > simpler VM physical address translation. > The second role of IOMMU is to allow protection from unwanted memory > access by an unsafe devise that has DMA privileges. Unfortunately this > protection comes with an extremely high performance costs for high speed > nics. > > To your question iommu=pt disables IOMMU support for the hypervisor. > > On Tue, Oct 21, 2014 at 1:39 AM, Xie, Huawei <huawei.xie at intel.com> wrote: > >> >> >> > -----Original Message----- >> > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Shivapriya >> Hiremath >> > Sent: Monday, October 20, 2014 2:59 PM >> > To: dev at dpdk.org >> > Subject: [dpdk-dev] Why do we need iommu=pt? >> > >> > Hi, >> > >> > My question is that if the Poll mode driver used the DMA kernel >> interface >> > to set up its mappings appropriately, would it still require that >> iommu=pt >> > be set? >> > What is the purpose of setting iommu=pt ? >> PMD allocates memory though hugetlb file system, and fills the physical >> address >> into the descriptor. >> pt is used to pass through iotlb translation. Refer to the below link. >> http://lkml.iu.edu/hypermail/linux/kernel/0906.2/02129.html >> > >> > Thank you. >> > >
