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Full Discussion: idle% cpu and run queue
Top Forums UNIX for Advanced & Expert Users idle% cpu and run queue Post 302683695 by jim mcnamara on Wednesday 8th of August 2012 10:39:41 AM
Old 08-08-2012
It is an artifact of sampling. For starters, it is an average value.

Let's look at an example:

The simplest example is a queue for a service, say an ATM machine. The queue can have nobody waiting there or sometimes as many as three people waiting. So, the average usage can be 50%, but on average when somebody gets there he has 1.5 people in front of him. There is no such thing as .5 of a person, of course.

What it says is that your cpu load is uneven with lots of no-load periods and lots of longer queues. Your result really shows that your system cpu resource is not heavily used. All is well. For the small timeframe you show.

sar is really great for gathering detail data but is not so great at assembling details into a useful report. I would use other resource measurement tools than sar, if you are going to be interpreting the output like a report.
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sar(1M) 						  System Administration Commands						   sar(1M)

NAME
sar, sa1, sa2, sadc - system activity report package SYNOPSIS
/usr/lib/sa/sadc [ t n] [ofile] /usr/lib/sa/sa1 [ t n] /usr/lib/sa/sa2 [-aAbcdgkmpqruvwy] [-e time] [-f filename] [-i sec] [-s time] DESCRIPTION
System activity data can be accessed at the special request of a user (see sar(1)) and automatically, on a routine basis, as described here. The operating system contains several counters that are incremented as various system actions occur. These include counters for CPU utilization, buffer usage, disk and tape I/O activity, TTY device activity, switching and system-call activity, file-access, queue activ- ity, inter-process communications, and paging. For more general system statistics, use iostat(1M), sar(1), or vmstat(1M). sadc and two shell procedures, sa1 and sa2, are used to sample, save, and process this data. sadc, the data collector, samples system data n times, with an interval of t seconds between samples, and writes in binary format to ofile or to standard output. The sampling interval t should be greater than 5 seconds; otherwise, the activity of sadc itself may affect the sam- ple. If t and n are omitted, a special record is written. This facility can be used at system boot time, when booting to a multi-user state, to mark the time at which the counters restart from zero. For example, when accounting is enabled, the svc:/sys- tem/sar:default service writes the restart mark to the daily data file using the command entry: su sys -c "/usr/lib/sa/sadc /var/adm/sa/sa'date +%d'" The shell script sa1, a variant of sadc, is used to collect and store data in the binary file /var/adm/sa/sadd, where dd is the current day. The arguments t and n cause records to be written n times at an interval of t seconds, or once if omitted. The following entries in /var/spool/cron/crontabs/sys will produce records every 20 minutes during working hours and hourly otherwise: 0 * * * 0-6 /usr/lib/sa/sa1 20,40 8-17 * * 1-5 /usr/lib/sa/sa1 See crontab(1) for details. The shell script sa2, a variant of sar, writes a daily report in the file /var/adm/sa/sardd. See the OPTIONS section in sar(1) for an explanation of the various options. The following entry in /var/spool/cron/crontabs/sys will report important activities hourly during the working day: 5 18 * * 1-5 /usr/lib/sa/sa2 -s 8:00 -e 18:01 -i 1200 -A FILES
/tmp/sa.adrfl address file /var/adm/sa/sadd Daily data file /var/adm/sa/sardd Daily report file /var/spool/cron/crontabs/sys ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWaccu | +-----------------------------+-----------------------------+ SEE ALSO
crontab(1), sag(1), sar(1), svcs(1), timex(1), iostat(1M), svcadm(1M), vmstat(1M), attributes(5), smf(5) System Administration Guide: Basic Administration NOTES
The sar service is managed by the service management facility, smf(5), under the service identifier: svc:/system/sar Administrative actions on this service, such as enabling, disabling, or requesting restart, can be performed using svcadm(1M). The ser- vice's status can be queried using the svcs(1) command. SunOS 5.10 20 Aug 2004 sar(1M)
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