What is Queue Lenghts?

[Luca Gabrielli]

Hello

I have some problem to define the Queue Lenghts over 1, 5, 15 minutes .
Someone can explain this concept to me?

Luca

[Peter Godron]

Luca,
could you please expand in which context?
Printers,Networking ...

[Bill Thorsteinson · Accepted solution]

I don't known which queue you are dealing
with. Loadavg is already available over
the periods you want.

This queue deals with then number of runnable
processes. The queue length is determined
by counting the number of runnable processes
every so often (each clock tick for example).
The number of runnable processes is the
averaged over period in question.

The number of disk accesss to a disk is
also availble, but not necessarily as easily.

There are two key variables in predicting
queue lengths; speed of arrival (how fast
new items enter the queue), average
transaction time (how long to process an
item in the queue).

Think grocery store, the express line
has different queueing characteristics than
the regular line. If the are six people in
the express line and you have one item,
do you line up there or in the regular line
with one person waiting.

Search on queueing theory for more details.

[Jean-Yves Picard]

Hello,

if you are refering to Queue length in uptime context

this mean numbre of proccess waiting to be run on CPU quota.
(process waiting on I/O either user interaction or disk do not count).

if Queue length is 5 : this meant that 5 process have been waiting to get CPU. increasing number of CPU would reduce queue length.

Jean-Yves Picard

[Luca Gabrielli]

"jobs"

I hope this can help!

[Carlos Roberto Schimidt]

Hi,

You can use "sar -q" for monitor run queue.

If you have more process wait for get cpu then processors, you have to investigate aplications or add more cpu.

Most of times investigate perfomance problems aplications decrease run queue.

[Peter Godron]

Luca,
for jobs:
For 1 Minute:
sar -A 60 1
for 5 monutes:
sar -A 300 1
for 15 minutes:
sar -A 900 1