On Thu, May 02, 2013 at 02:11:15AM +0300, Or Gerlitz wrote: > Hi Roland, IOMMU folks, > > So we've noted that when configuring the kernel && booting with intel > iommu set to on on a physical node (non VM, and without enabling SRIOV > by the HW device driver) raw performance of the iSER (iSCSI RDMA) SAN > initiator is reduced notably, e.g in the testbed we looked today we > had ~260K 1KB random IOPS and 5.5GBs BW for 128KB IOs with iommu > turned off for single LUN, and ~150K IOPS and 4GBs BW with iommu > turned on. No change on the target node between runs.
That's why we have iommu=pt. See definition of iommu_pass_through in arch/x86/kernel/pci-dma.c. _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
