
Solarflare
Server
Adapter
User
Guide
Solarflare
Adapters
on
Windows
Issue
20
©
Solarflare
Communications
2017
163
Checksum
Offload
Checksum
offloading
is
supported
on
IP,
TCP
and
UDP
packets.
Before
transmitting
a
packet,
a
checksum
is
generated
and
appended
to
the
packet.
At
the
receiving
end,
the
same
checksum
calculation
is
performed
against
the
received
packet.
By
offloading
the
checksum
process
to
the
network
adapter,
the
load
is
decreased
on
the
server
CPU.
By
default,
Solarflare
adapters
are
set
up
to
offload
both
the
calculation
and
verification
of
TCP,
IP
and
UDP
checksums.
The
following
Checksum
Offload
options
are
supported:
You
can
also
configure
Checksum
Offload
settings
from
the
network
adapter
properties.
See
for
more
details.
NOTE:
Changing
the
Checksum
Offload
settings
can
impact
the
performance
of
the
adapter.
Solarflare
recommend
that
these
remain
at
the
default
values.
Disabling
Checksum
Offload
disables
Large
Send
Offload.
RSS
and
Interrupts
Solarflare
network
adapters
support
RSS
(Receive
Side
Scaling)
and
interrupt
moderation.
Both
are
enabled
by
default
and
can
significantly
improve
the
performance
of
the
host
CPU
when
handling
large
amounts
of
network
data.
RSS
attempts
to
dynamically
distribute
data
processing
across
the
available
host
CPUs
in
order
to
spread
the
workload.
Interrupt
moderation
is
a
technique
used
to
reduce
the
number
of
interrupts
sent
to
the
CPU.
With
interrupt
moderation,
the
adapter
will
not
generate
interrupts
closer
together
than
the
interrupt
moderation
interval.
An
initial
packet
will
generate
an
interrupt
immediately,
but
if
subsequent
packets
arrive
before
the
interrupt
moderation
interval,
interrupts
are
delayed.
Table
35:
Checksum
Offloads
Check
box
selected
Transmit
and
Receive
Transmit
checksums
are
generated
and
received
checksums
are
enabled.
This
is
the
default
setting.
Check
selected
but
selection
grayed
out
Transmit
Only
or
Receive
Only
For
either
transmit
or
received
checksum
only.
NOTE:
The
Transmit
or
Receive
Only
states
can
only
be
set
from
the
Advanced
tab
of
the
Driver
Properties.
See
for
more
details.
Check
box
cleared
Disabled
Disabled.
Data
will
be
checksummed
by
the
host
processor
for
both
transmitted
and
received
data.