Issue 11
© Solarflare Communications 2014
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Solarflare Server Adapter
User Guide
To force processing onto a particular NUMA Node, change the RSS NUMA Node setting on the
Network Adapter's Advanced Properties Page.
Other Considerations
PCI Express Lane Configurations
The PCI Express (PCIe) interface used to connect the adapter to the server can function at different
speeds and widths. This is independent of the physical slot size used to connect the adapter. The
possible widths are multiples x1, x2, x4, x8 and x16 lanes of (2.5Gbps for PCIe Gen 1, 5.0 Gbps for
PCIe Gen 2 and 8.0Gbps for PCIe Gen 3) in each direction.
Solarflare adapters are designed for x8
or x16 lane operation
.
On some server motherboards, choice of PCIe slot is important. This is because some slots (including
those that are physically x8 or x16 lanes) may only electrically support x4 lanes. In x4 lane slots,
Solarflare PCIe adapters will continue to operate, but not at full speed. The Solarflare driver will
insert a warning in the Windows Event Log if it detects that the adapter is plugged into a PCIe slot
which electrically has fewer than x8 lanes.
For SFN5xxx and SFN6xxx Solarflare adapters, which require a PCIe Gen 2 x8 slot for optimal
operation. Solarflare SFN7xxx series adapters require a PCIe Gen 3 x8 or x16 slot for optimal
performance. A warning will be issued when the Solarflare adapter is placed in a sub-optimal slot.
In addition, the latency of communications between the host CPUs, system memory and the
Solarflare PCIe adapter may be PCIe slot dependant. Some slots may be “closer” to the CPU, and
therefore have lower latency and higher throughput. Please consult your server user guide for more
information.
Memory bandwidth
Many chipsets use multiple channels to access main system memory. Maximum memory
performance is only achieved when the chipset can make use of all channels simultaneously. This
should be taken into account when selecting the number of memory modules (DIMMs) to populate
in the server. Consult the motherboard documentation for details, however it’s likely that populating
all DIMM slots will be needed for optimal memory bandwidth in the system.
NOTE:
Solarflare recommend that you do not change this setting.