Solarflare Solarflare XtremeScale series, Руководство пользователя, Страница: 122 / 400

Solarflare Server Adapter User Guide
Solarflare Adapters on Linux
Issue 20 © Solarflare Communications 2017 115
Example 2:
An example of affinitizing each interface to a CPU on the same package:
First identify which interrupt lines are servicing which CPU and IO device:
# cat /proc/interrupts | grep eth0 ‐

123: 13302 0 1278131 0 PCI ‐ MSI ‐ X eth0 ‐ 0

# cat /proc/interrupts | grep eth1 ‐

131: 0 24 0 0 PCI ‐ MSI ‐ X eth1 ‐ 0
Find CPUs on same package (have same ‘package ‐ id’):
# more /sys/devices/system/cpu/cpu*/topology/physical_package_id

::::::::::::::

/sys/devices/system/cpu/cpu0/topology/physical_package_id

::::::::::::::

1

::::::::::::::

/sys/devices/system/cpu/cpu10/topology/physical_package_id

::::::::::::::

1

::::::::::::::

/sys/devices/system/cpu/cpu11/topology/physical_package_id

::::::::::::::

0

…
Having determined that cpu0 and cpu10 are on package 1, we can assign each ethX
interface’s MSI ‐ X interrupt to its own CPU on the same package. In this case we
choose package 1:
# echo 1 > /proc/irq/123/smp_affinity # 1hex is bit 0 = CPU0

# echo 400 > /proc/irq/131/smp_affinity # 400hex is bit 10 = CPU10
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 warn if it detects that the adapter is
plugged into a PCIe slot which electrically has fewer than x8 lanes.
Solarflare SFN5000 and SFN6000 series adapters require a PCIe Gen 2 x8 slot for
optimal operation. Solarflare SFN7000 and SFN8000 series adapters require a PCIe
Gen 3 x8 or x16 slot for optimal performance. The Solarflare driver will warn if it
detects that the adapter is placed in a sub ‐ optimal slot.