topic Re: Load Average in Operating System - Linux

Load Average

Sundar_7 — Tue, 12 Jun 2007 15:24:33 GMT

Folks,

How would you explain this load average ? Per my understanding, load average is the average of the number of processes in the run queue. System is 97.6% idle but still a load average of 10 ?

top - 10:36:03 up 314 days, 1:45, 2 users, load average: 10.66, 10.23, 7.25
Tasks: 82 total, 1 running, 81 sleeping, 0 stopped, 0 zombie
Cpu(s): 0.1% us, 1.4% sy, 0.0% ni, 97.6% id, 0.8% wa, 0.0% hi, 0.0% si

Sundar.

Re: Load Average

Ivan Ferreira — Tue, 12 Jun 2007 19:19:31 GMT

Hi Sundar, here is a good explanatio of load average:

http://www.redhat.com/magazine/011sep05/departments/tips_tricks/

Re: Load Average

skt_skt — Tue, 12 Jun 2007 20:51:09 GMT

load average=number of processes in the run queue waiating for CPU time/"number of processor"

load avaerage will be 5 if there are 4 cpus and 20 processes currently in the queue.I have noticed that this has been increasing gradually , but there was not real performance problem.

Re: Load Average

Stuart Browne — Tue, 12 Jun 2007 20:59:08 GMT

Santhosh, not under Linux it isn't.

Re: Load Average

Steven E. Protter — Wed, 13 Jun 2007 01:03:02 GMT

Shalom,

Lots of processes waiting, never getting the resources they need.

Bug. The system has been running a long time between boots.

I'd look at what processes are running and their state. There should be an explanation in that analysis.

SEP

Re: Load Average

Sundar_7 — Wed, 13 Jun 2007 09:08:04 GMT

The following paragraph from the Redhat website explains it all

"Some other operating systems calculate their load averages simply by looking at processes in R state. On those systems, load average is synonymous with the run queue -- high load averages mean that the box is CPU bound.

This is not the case with Linux. On Linux the load average is a measurement of the amount of "work" being done by the machine (without being specific as to what that work is). This "work" could reflect a CPU intensive application (compiling a program or encrypting a file), or something I/O intensive (copying a file from disk to disk, or doing a database full table scan), or a combination of the two.

"

The load average is computed differently in HP-UX and Linux.

Re: Load Average

Sundar_7 — Fri, 15 Jun 2007 10:39:31 GMT

Redhat website explains the difference in the algorithm used to computer load average between Linux and other UNIX variants. Closing the thread.