Solarflare Solarflare XtremeScale series, User Manual, Page: 118 / 400

Solarflare Server Adapter User Guide
Solarflare Adapters on Linux
Issue 20 © Solarflare Communications 2017 111
Driver Tuning
Whilst most driver enhancements are internal changes, transparent and non ‐
configurable by the user, the following driver module options can be used to tune
the driver for particular user applications.
• rss_numa_local
Using the 4.4.1.1017 driver this option is enabled by default. This will restrict
RSS to use CPU cores only on the NUMA node closest to the adapter. This is
particularly important for processors supporting DDIO.
RSS channels not on the local NUMA node can still be accessed using the
ethtool ‐ U
commands to identify a core (action) on which to process the
specified ethtool ntuple filter traffic. For example if
rss_cpus=cores
, then an
RSS receive channel and associated MSI ‐ X interrupt is created for every core.
• rx_recycle_ring_size
The default value for the maximum number of receive buffers to recycle pages
for has been changed to 512, and in newer drivers will be further increased to
1024.
• rx_copybreak
A default value of 192 bytes has been selected as the maximum size of packet
(bytes) that will be copied directly to the network stack.
Driver module options can be enabled in a user ‐ created file (e.g sfc.conf) in the
/
etc/modprobe.d
directory, for example:
options sfc rss_numa_local=Y

options sfc rx_recycle_ring_size=512
For further descriptions and to list all sfc driver module options:
# modinfo sfc
nginx Tuning
Table 23: nginx Server Tuning
Tuning Notes
SO_REUSEPORT Solarflare testing involving nginx used version v1.7.9
with applied patch to support so_reuseport. See the
following link for details: http://forum.nginx.org/
read.php?29,241283,241283 .
rss_cpus=N Create N receive queues where N=(number of logical
cores)/2.
See Receive Side Scaling (RSS) on page 81 for
options.