Solarflare
Server
Adapter
User
Guide
Solarflare
Adapters
on
Linux
Issue
20
©
Solarflare
Communications
2017
110
TX
PIO
PIO
(programmed
input/output)
describes
the
process
where
data
is
directly
transferred
by
the
CPU
to
or
from
an
I/O
device.
It
is
an
alternative
technique
to
the
I/O
device
using
bus
master
DMA
to
transfer
data
without
CPU
involvement.
Solarflare
SFN7000
and
SFN8000
series
adapters
support
TX
PIO,
where
packet
s
on
the
transmit
path
can
be
“pushed”
to
the
adapter
directly
by
the
CPU.
This
improves
the
latency
of
transmitted
packets
but
can
cause
a
very
small
increase
in
CPU
utilization.
TX
PIO
is
therefore
especially
useful
for
smaller
packets.
The
TX
PIO
feature
is
enabled
by
default
for
packets
up
to
256
bytes.
The
maximum
packet
size
that
can
use
PIO
can
be
configured
with
the
driver
module
option
piobuf_size
.
3.25
Web
Server
‐
Driver
Optimization
Introduction
The
Solarflare
net
driver
from
version
4.4.1.1017
on
Solarflare
SFN7000
and
SFN8000
series
adapters
includes
optimizations
aimed
specifically
at
web
service
providers
and
cloud
based
applications.
Tuning
recommendations
are
documented
in
for
users
concerned
with
Content
Delivery
Networks
(CDN),
HTTP
web
hosting
application
technologies
such
as
HA
Proxy,
nginx
and
HTTP
web
servers.
When
tested
on
the
Solarflare
SFN7122
and
SFN7002
adapters
using
the
recommended
driver
and
firmware
with
minimal
driver/hardware
tunings,
performance
improvements
have
been
observed
in
the
following
areas:
•
increased
the
rate
at
which
servers
can
process
new
HTTP
connections
•
increased
the
rate
at
which
servers
can
process
HTTP
requests
•
increased
sustained
throughput
when
processing
large
files
via
HTTP
•
improved
kernel
throughput
performance
Customers
requiring
further
details
or
to
access
test
data
should
send
an
to