Re: High load average in 64-core server , no I/O wait and CPU is idle

From: "Rajesh Kumar(dot) Mallah" <mallah(at)tradeindia(dot)com>
To: Claudio Freire <klaussfreire(at)gmail(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: High load average in 64-core server , no I/O wait and CPU is idle
Date: 2012-05-24 06:54:17
Message-ID: 17861168.278931337842457837.JavaMail.root@zmbox01.trade-india-local.com
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|
| Load avg is the number of processes in the running queue, which can
| be either waiting to be run or actually running.
|
| So if you had 100% CPU usage, then you'd most definitely have a load
| avg of 64, which is neither good or bad. It may simply mean that
| you're using your hardware's full potential.

Dear Claudio ,

Thanks for the reply and clarifying on the "actually running" part.

below is a snapshot of the top output while the system was loaded.

top - 12:15:13 up 101 days, 19:01, 1 user, load average: 23.50, 18.89, 21.74
Tasks: 650 total, 11 running, 639 sleeping, 0 stopped, 0 zombie
Cpu(s): 26.5%us, 5.7%sy, 0.0%ni, 67.2%id, 0.0%wa, 0.0%hi, 0.6%si, 0.0%st
Mem: 131971752k total, 122933996k used, 9037756k free, 251544k buffers
Swap: 33559780k total, 251916k used, 33307864k free, 116356252k cached

Our applications does slowdown when loads are at that level. Can you please
tell what else can be metered?

|
| If your processes are waiting but not using CPU or I/O time... all I
| can think of is mcelog (it's the only application I've ever witnessed
| doing that). Do check ps/top and try to find out which processes are
| in a waiting state to have a little more insight.

I will read more on the processes status and try to keep a close
eye over it. I shall be responding after a few hours on it.

regds
mallah.

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