Dell Emulex Family of Adapters - Manual (Page 838)

Emulex Drivers Version 10.2 for Linux User Manual P010081-01A Rev. A
3. Configuration
Ethernet Driver Configuration
838
SR-IOV Configuration
Introduction
This section contains requirements and instructions to use SR-IOV with the following
host operating systems:

Red Hat Enterprise Linux 6.3 - 64-bit KVM

Red Hat Enterprise Linux 6.4 - 64-bit KVM

Red Hat Enterprise Linux 6.5 - 64-bit KVM

SuSE Linux Enterprise Server 11 SP2 - 64-bit Xen and KVM

SLES and RHEL supported with Xen
These environments support capabilities of OneConnect to enable multiple PCIe virtual
functions (VFs) for a PCIe physical function (PF). Each of these VFs can be assigned to
virtual machines (VMs). A VF enables the guest operating system direct access to
OneConnect, such that guest performance is not limited by the overheads of the
hypervisor.
With SR-IOV, VMs directly drive I/Os on the NIC. Therefore, SR-IOV has the following
advantages over traditional virtualized I/O:

Reduced CPU utilization

Reduced latency

Increased scalability

Improved device performance for virtual guests
Known issues include:

On RHEL 6.3 (or earlier) and SLES 11 SP2 (or earlier) systems, any attempt to
disable SR-IOV by the driver in hypervisor when VFs are assigned to VMs leads
to undefined behavior. This known issue needs to be corrected in the kernel. As
a result of this issue in these kernel distributions, once an Ethernet driver is
loaded with a non-zero value for num_vfs, the driver can never be unloaded.
The only way to reload the driver with a different num_vfs value is to reboot
the system.

The Kdump (kernel dump) feature is not supported when SR-IOV is enabled.