Solarflare
Server
Adapter
User
Guide
Solarflare
Adapters
on
VMware
Issue
20
©
Solarflare
Communications
2017
283
Binding
NetQueue
queues
and
Virtual
Machines
to
CPUs
Depending
on
the
workload,
NetQueue
can
show
improved
performance
if
each
of
the
queues’
associated
interrupt
and
the
virtual
machine
are
pinned
to
the
same
CPU.
This
is
particularly
true
of
workloads
where
sustained
high
bandwidth
is
evenly
distributed
across
multiple
virtual
machines
(such
as
you
might
do
when
benchmarking).
To
pin
a
Virtual
Machine
to
one
or
more
CPUs:
1
Log
in
to
the
VMware
Infrastructure
Client.
2
Expand
the
host
and
select
the
virtual
machine
to
pin
from
the
inventory
panel.
3
Select
the
Summary
tab
for
that
virtual
machine.
4
Click
Edit
Settings
.
5
From
the
resulting
dialog
box
select
the
Resources
tab
6
Click
Advanced
CPU
on
the
left.
7
Select
the
CPU(s)
to
which
the
virtual
machine
is
to
be
bound
(on
the
right
hand
side
of
the
dialog
box).
To
bind
a
queue’s
interrupt
to
a
CPU,
from
the
VMware
ESX
console
OS
enter:
#
echo
move
$IRQVEC
$CPU
>
/proc/vmware/intr
‐
tracker
(Where
$IRQVEC
is
the
interrupt
vector
in
hex,
and
$CPU
is
the
CPU
number
in
decimal.)
To
determine
the
value
for
$IRQVEC
enter:
#
cat
/proc/vmware/interrupts
Locate
the
interrupts
associated
with
the
Solarflare
adapter
(e.g.
vmnic2).
Interrupts
are
listed
in
order:
the
first
interrupt
will
be
for
the
default
queue,
the
second
interrupt
for
the
queue
dedicated
to
the
first
virtual
machine
to
have
been
started,
the
third
interrupt
for
the
queue
dedicated
to
the
second
virtual
machine
to
have
been
started,
and
so
on.
If
there
are
more
virtual
machine’s
than
CPUs
on
the
host,
optimal
performance
is
obtained
by
pinning
each
virtual
machine
and
associated
interrupt
to
the
same
CPU.
If
there
are
fewer
virtual
machines
than
CPUs,
optimal
results
are
obtained
by
pinning
the
virtual
machine
and
associated
interrupt
respectively
to
two
cores
which
share
an
L2
cache.
Adapter
MTU
(Maximum
Transmission
Unit)
The
default
MTU
of
1500
bytes
ensures
that
the
adapter
is
compatible
with
legacy
10/100Mbps
Ethernet
endpoints.
However
if
a
larger
MTU
is
used,
adapter
throughput
and
CPU
utilization
can
be
improved.
CPU
utilization
is
improved
because
it
takes
fewer
packets
to
send
and
receive
the
same
amount
of
data.
Solarflare
adapters
support
frame
sizes
up
to
9216
bytes
(this
does
not
include
the
Ethernet
preamble
or
frame
‐
CRC).