[dpdk-dev] Why do we need iommu=pt?

2014-10-30 Thread Shivapriya Hiremath
Thank you Danny. This is helpful info. Regards, Shivapriya Hiremath On Thu, Oct 30, 2014 at 4:22 PM, Zhou, Danny wrote: > Shivapriya, Alex > > There is obvious performance (up to 40% perf. drop) impact to DPDK 64B > small packet performance when ?iommu = on? on Sandybridge,

[dpdk-dev] Why do we need iommu=pt?

2014-10-27 Thread Shivapriya Hiremath
> and VMs) which could > > > > direct access NIC and DMA engine inside the NIC using modified DPDK > PMD > > > > are not trustable > > > > as they can potentially DAM to/from arbitrary memory regions using > > > > physical addresses, so IOMMU >

[dpdk-dev] Why do we need iommu=pt?

2014-10-21 Thread Shivapriya Hiremath
cs. > > To your question iommu=pt disables IOMMU support for the hypervisor. > > On Tue, Oct 21, 2014 at 1:39 AM, Xie, Huawei wrote: > >> >> >> > -Original Message- >> > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Shivapriya &g

[dpdk-dev] Why do we need iommu=pt?

2014-10-20 Thread Shivapriya Hiremath
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 ? Thank you.