An Explanation of *nix system load averages - GoFuckYourself.com

V_RocKs · 02-25-2010, 04:03 PM

Wondering if your current system has balls or not? Perhaps you have been around since the time of single core processors and single CPU servers and are wondering what those three little numbers mean in today's systems.

Here is a simplified explanation of what system load averages mean.

First, I'll let you know why I am even posting this. One of my hosts was telling me my loads are too high. Wordpress was supposedly slowing my server down. I looked into it and the sites on the server seemed to load just fine... No, make that, they loaded exceptionally quick.

So he showed me my averages: 1.71 1.86 1.83

He proceeded to tell me that anything over 1 means processes are waiting for CPU time and therefor my surfers were waiting too!

I looked into it. His example would have worked back in the day of a single Pentium processor running the machine. I had a quad CPU XEON setup. You probably have something better than 1 CPU or processor core on your system. So how do you read load averages then?

So, that simplified explanation. Those three numbers are telling you what your load averages are for the past 1 minute, 5 minutes and 15 minutes respectively. They are scaled on a 1 processor system. So they don't recalibrate for your dual or quad core/CPU systems.

On my quad core system I have 4 pipes. Only 1.71 pipes were filled in the last minute. So 2.29 were sitting around doing nothing.

In his example only a single core/CPU system would have been overloaded. On a dual core/CPU system it would be right around where you could feel comfortable. On a quad core/CPU system I actually could consider my "engine" a bit of overkill! Then again, I have logs that get parsed into stats around midnight and various cronjobs that push my system into the 2.90 - 3.60 ranges. So my system is actually just about right for its overall system load averages throughout a 24 hour period.

Hope this helps some of you make better/informed decisions when choosing your next server upgrade or when deciding if it isn't really needed.

EdgeXXX · 02-25-2010, 04:15 PM

You are correct and that was well explained.

greg80 · 02-25-2010, 04:45 PM

load average: 17.18, 15.67, 15.41

On dual core

V_RocKs · 02-25-2010, 05:11 PM

Quote:

Originally Posted by greg80

load average: 17.18, 15.67, 15.41

On dual core

ps aux|grep php|awk {'print $2'}|xargs kill -9

BIGTYMER · 02-25-2010, 05:58 PM

That is great info. I had no clue they were based off of 1 cpu.

02-25-2010, 04:03 PM	#1
V_RocKs Damn Right I Kiss Ass! Industry Role: Join Date: Dec 2003 Location: Cowtown, USA Posts: 32,409	*An Explanation of nix system load averages** Wondering if your current system has balls or not? Perhaps you have been around since the time of single core processors and single CPU servers and are wondering what those three little numbers mean in today's systems. Here is a simplified explanation of what system load averages mean. First, I'll let you know why I am even posting this. One of my hosts was telling me my loads are too high. Wordpress was supposedly slowing my server down. I looked into it and the sites on the server seemed to load just fine... No, make that, they loaded exceptionally quick. So he showed me my averages: 1.71 1.86 1.83 He proceeded to tell me that anything over 1 means processes are waiting for CPU time and therefor my surfers were waiting too! I looked into it. His example would have worked back in the day of a single Pentium processor running the machine. I had a quad CPU XEON setup. You probably have something better than 1 CPU or processor core on your system. So how do you read load averages then? So, that simplified explanation. Those three numbers are telling you what your load averages are for the past 1 minute, 5 minutes and 15 minutes respectively. They are scaled on a 1 processor system. So they don't recalibrate for your dual or quad core/CPU systems. On my quad core system I have 4 pipes. Only 1.71 pipes were filled in the last minute. So 2.29 were sitting around doing nothing. In his example only a single core/CPU system would have been overloaded. On a dual core/CPU system it would be right around where you could feel comfortable. On a quad core/CPU system I actually could consider my "engine" a bit of overkill! Then again, I have logs that get parsed into stats around midnight and various cronjobs that push my system into the 2.90 - 3.60 ranges. So my system is actually just about right for its overall system load averages throughout a 24 hour period. Hope this helps some of you make better/informed decisions when choosing your next server upgrade or when deciding if it isn't really needed.

02-25-2010, 04:15 PM	#2
EdgeXXX Confirmed User Join Date: Nov 2005 Location: Secretely plotting a hostile takeover Posts: 5,816	You are correct and that was well explained. __________________ . . . . I have a sig

02-25-2010, 04:45 PM	#3
greg80 Confirmed User Industry Role: Join Date: May 2007 Posts: 1,644	load average: 17.18, 15.67, 15.41 On dual core __________________ Say no to GoDaddy and high renewal prices! Go with NameSilo - FREE private whois for life, $8.99 regstrations and renewals. Free redirects, emails, great control panel and more! NameSilo rocks!

02-25-2010, 05:58 PM	#5
BIGTYMER Junior Achiever Industry Role: Join Date: Nov 2004 Location: Walled Garden Posts: 17,066	That is great info. I had no clue they were based off of 1 cpu.