
Solarflare
Server
Adapter
User
Guide
Solarflare
Adapters
on
Linux
Issue
20
©
Solarflare
Communications
2017
119
Recommended
Latency
Tuning
shows
recommended
tuning
settings
for
latency:
PCI
Express
Lane
Configuration
Ensure
the
adapter
is
in
an
x8
slot
(2.0
or
later),
and
that
current
speed
(not
the
supported
speed)
reads
back
as
“x8
and
5GT/s”,
or
“x8
and
8GT/s”,
or
“x8
and
Unknown”.
CPU
Speed
Service
(cpuspeed)
Leave
enabled.
Memory
bandwidth
Ensure
memory
utilizes
all
memory
channels
on
system
motherboard.
Intel
QuickData
(Intel
chipsets
only)
Enable
in
BIOS
and
install
driver:
modprobe
ioatdma
Table
25:
Latency
Tuning
Settings
Tuning
Parameter
How?
MTU
Size
Configure
to
maximum
supported
by
network:
/sbin/ifconfig
<ethX>
mtu
<size>
Interrupt
moderation
Disable
with:
ethtool
‐
C
<ethX>
rx
‐
usecs
‐
irq
0
TCP/IP
Checksum
Offload
Leave
at
default
(Enabled).
TCP
Segmentation
Offload
Leave
at
default
(Enabled).
TCP
Large
Receive
Offload
Disable
using
sysfs:
echo
0
>
/sys/class/net/ethX/device/lro
TCP
Protocol
Tuning
Leave
at
default,
but
changing
does
not
impact
latency.
Receive
Side
Scaling
Application
dependent.
Interrupt
affinity
&
irqbalance
service
Interrupt
affinity
settings
are
application
dependent
Stop
irq
balance
service:
/sbin/service
irqbalance
stop
Reload
the
drivers
to
use
the
driver
default
interrupt
affinity.
Table
24:
Throughput
Tuning
Settings
Tuning
Parameter
How?