I am currently testing PCI passthrough on the Skylake-SP platform using a
Supermicro X11SPi-TF mainboard. Using PCI passthrough (an LSI SAS HBA)
causes severe performance loss on the Skylake-SP platform while Xeon E3 v5
is not affected at all. The test uses standard iperf3 as a client - the
passed PCI device is not used in the test - so that just the presence of
the passed device will cause the iperf3 performance to drop from 6.5
gbit/sec (no passthrough) to 4.5 gbit/sec.
Any explanation/fixes for that?
Below the first part of xl dmesg for both systems.
Regards Andreas
Xeon E3-1240v5:
(XEN) Intel VT-d iommu 0 supported page sizes: 4kB, 2MB, 1GB.
(XEN) Intel VT-d Snoop Control enabled.
(XEN) Intel VT-d Dom0 DMA Passthrough not enabled.
(XEN) Intel VT-d Queued Invalidation enabled.
(XEN) Intel VT-d Interrupt Remapping enabled.
(XEN) Intel VT-d Posted Interrupt not enabled.
(XEN) Intel VT-d Shared EPT tables enabled.
(XEN) 0000:00:13.0: unknown type 0
(XEN) I/O virtualisation enabled
(XEN) - Dom0 mode: Relaxed
(XEN) Interrupt remapping enabled
(XEN) Enabled directed EOI with ioapic_ack_old on!
(XEN) ENABLING IO-APIC IRQs
(XEN) -> Using old ACK method
(XEN) Allocated console ring of 16 KiB.
(XEN) VMX: Supported advanced features:
(XEN) - APIC MMIO access virtualisation
(XEN) - APIC TPR shadow
(XEN) - Extended Page Tables (EPT)
(XEN) - Virtual-Processor Identifiers (VPID)
(XEN) - Virtual NMI
(XEN) - MSR direct-access bitmap
(XEN) - Unrestricted Guest
(XEN) - VMCS shadowing
(XEN) - VM Functions
(XEN) - Virtualisation Exceptions
(XEN) - Page Modification Logging
(XEN) HVM: ASIDs enabled.
(XEN) HVM: VMX enabled
(XEN) HVM: Hardware Assisted Paging (HAP) detected
(XEN) HVM: HAP page sizes: 4kB, 2MB, 1GB
Skylake-SP:
(XEN) Intel VT-d iommu 2 supported page sizes: 4kB, 2MB, 1GB.
(XEN) Intel VT-d iommu 1 supported page sizes: 4kB, 2MB, 1GB.
(XEN) Intel VT-d iommu 0 supported page sizes: 4kB, 2MB, 1GB.
(XEN) Intel VT-d iommu 3 supported page sizes: 4kB, 2MB, 1GB.
(XEN) Intel VT-d Snoop Control enabled.
(XEN) Intel VT-d Dom0 DMA Passthrough not enabled.
(XEN) Intel VT-d Queued Invalidation enabled.
(XEN) Intel VT-d Interrupt Remapping enabled.
(XEN) Intel VT-d Posted Interrupt not enabled.
(XEN) Intel VT-d Shared EPT tables enabled.
(XEN) I/O virtualisation enabled
(XEN) - Dom0 mode: Relaxed
(XEN) Interrupt remapping enabled
(XEN) Enabled directed EOI with ioapic_ack_old on!
(XEN) ENABLING IO-APIC IRQs
(XEN) -> Using old ACK method
(XEN) Allocated console ring of 128 KiB.
(XEN) VMX: Supported advanced features:
(XEN) - APIC MMIO access virtualisation
(XEN) - APIC TPR shadow
(XEN) - Extended Page Tables (EPT)
(XEN) - Virtual-Processor Identifiers (VPID)
(XEN) - Virtual NMI
(XEN) - MSR direct-access bitmap
(XEN) - Unrestricted Guest
(XEN) - APIC Register Virtualization
(XEN) - Virtual Interrupt Delivery
(XEN) - Posted Interrupt Processing
(XEN) - VMCS shadowing
(XEN) - VM Functions
(XEN) - Virtualisation Exceptions
(XEN) - Page Modification Logging
(XEN) - TSC Scaling
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