Information Technology Reference
In-Depth Information
Although
prctl
will display the setting and
prstat
will display the CPU uti-
lization rate, the
kstat
command will display both pieces of information, if you
first determine the Container's ID number with
zoneadm
.
GZ#
zoneadm list -cv
ID NAME STATUS PATH BRAND IP
0 global running / native shared
1 myzone running /zones/roots/myzone native shared
GZ#
kstat 'caps:1:cpucaps_zone_1'
module: caps instance: 1
name: cpucaps_zone_1 class: zone_caps
above_sec 0
below_sec 7
crtime 115643.232135332
maxusage 111
nwait 0
snaptime 115650.048256739
usage 14
value 300
zonename myzone
The output of
kstat
shows that the Container is currently using approximately
14% of a CPU, and has used as much as 111% of a CPU during one measurement
sample.
Yo u c a n c o m b i n e a C P U c a p w i t h F S S t o e n s u r e t h a t a C o n t a i n e r r e c e i v e s a
specific minimum amount of compute time, but no more than another amount. It
does not make sense to apply both a CPU cap
and
a pool to a Container, and the
kernel does not allow it.
CPU controls should be used to prevent one workload from using more CPU
time than it should, either accidentally or intentionally as a result of a denial-of-
service attack.
Choosing a CPU Control
Each of those CPU controls affects processing in
different ways. Which one should you use? Every situation is different, but some
general statements can be made:
FSS is the best all-around CPU control. All Containers can access all of the
CPUs, so there are never idle CPU cycles that cannot be used by a Container
that is trying to use more—which is sometimes a problem with dedicated
CPUs or a CPU cap. A new Container can be added without reassigning
CPUs, which may be required when using dedicated CPUs. However, the
FSS algorithm can consume an unacceptable amount of CPU time if dozens
of Containers must be scheduled.
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