
Solarflare
Server
Adapter
User
Guide
Solarflare
Adapters
on
FreeBSD
Issue
20
©
Solarflare
Communications
2017
308
Interrupt
moderation
is
changed
dynamically
using
sysctl
.
To
set
the
interrupt
moderation,
where
sfxge<n>
is
the
interface
name,
and
the
<interval>
is
in
microseconds
(
μ
s):
sysctl
dev.sfxge.<n>.int_mod=<interval>
To
turn
off
interrupt
moderation,
set
an
interval
of
zero
(0):
sysctl
dev.sfxge.<n>.int_mod=0
The
change
in
interrupt
moderation
can
be
made
to
persist
across
reboots
by
editing
the
file
/etc/sysctl.conf
and
adding
dev.sfxge.<n>.int_mod=<interval>
on
a
new
line.
NOTE:
The
performance
benefits
of
TCP
Large
Receive
Offload
are
limited
if
interrupt
moderation
is
disabled.
See
.
TCP/IP
Checksum
Offload
Checksum
offload
moves
calculation
and
verification
of
IP
Header,
TCP
and
UDP
packet
checksums
to
the
adapter.
The
driver
has
all
checksum
offload
features
enabled
by
default.
Therefore,
there
is
no
opportunity
to
improve
performance
from
the
default.
Checksum
offload
is
changed
dynamically
using
ifconfig
,
with
the
following
parameters:
•
rxcsum
,
txcsum
,
rxcsum6
,
txcsum6
Enable
Rx
and
Tx
checksum
offload
for
IPv4
and
IPv6
•
‐
rxcsum
,
‐
txcsum
,
‐
rxcsum6
,
‐
txcsum6
Disable
Rx
and
Tx
checksum
offload
for
IPv4
and
IPv6
To
enable
checksum
offload,
where
sfxge<n>
is
the
interface
name:
#
ifconfig
sfxge<n>
rxcsum
txcsum
rxcsum6
txcsum6
To
disable
checksum
offload:
#
ifconfig
sfxge<n>
‐
rxcsum
‐
txcsum
‐
rxcsum6
‐
txcsum6
Verification
of
the
checksum
offload
setting
may
be
performed
by
running
ifconfig
with
no
options
and
checking
the
checksum
offload
value
associated
with
the
interface.
The
change
in
checksum
offload
can
be
made
to
persist
across
reboots
by
editing
the
/etc/rc.conf
file
and
adding
the
appropriate
parameters
to
the
single
line
of
interface
configuration
data.
For
example:
ifconfig_sfxge<n>="inet
<IPv4
address>
netmask
<netmask>
rxcsum
txcsum
rxcsum6
txcsum6"
NOTE:
Solarflare
recommend
you
do
not
disable
checksum
offload.
TCP
Segmentation
Offload
(TSO)
TCP
Segmentation
Offload
(TSO)
offloads
the
splitting
of
outgoing
TCP
data
into
packets
to
the
adapter.
TSO
benefits
applications
using
TCP.
Applications
using
protocols
other
than
TCP
will
not
be
affected
by
TSO.