I am getting pages from my hobbit server when some of my linux systems are hitting 15 on their load avg. does that equate to something worse than it sounds? Cause 15% load average on a linux system does not seem that bad? Or is it not a percentage?
Gavin Leonard
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Load is a measure of how many processes are running or runnable and is
not directly related to % of CPU used. There are cases where Load
average is through the roof but CPU % is very low, usually when when
the server is having issues talking to NFS storage or accessing some
kind of I/O resource.
We generally monitor load average based on number of CPUs in the box.
Our standard is yellow at 1.5 * # CPUs and red at 2 * # CPUs. YMMV.
On Oct 8, 2008, at 5:16 PM, Gavin Leonard wrote:
I am getting pages from my hobbit server when some of my linux
systems are hitting 15 on their load avg. does that equate to
something worse than it sounds? Cause 15% load average on a linux
system does not seem that bad? Or is it not a percentage?Gavin Leonard <image001.gif> Director, Systems-Network Engineering T 801-828-1735 F 801-828-1704 E gleonard at progrexion.com
Research | Marketing | Sales Generation www.progrexion.com
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On Wed, Oct 8, 2008 at 22:16, Gavin Leonard <gleonard at progrexion.com> wrote:
I am getting pages from my hobbit server when some of my linux systems are hitting 15 on their load avg. does that equate to something worse than it sounds? Cause 15% load average on a linux system does not seem that bad? Or is it not a percentage?
http://en.wikipedia.org/wiki/Load_(computing)
The Load Average is the number of processes requiring processor time. What it means depends on the number of processors - a load average of 6 is fine for a system with 8 processors, but not good news for one with only a single processor. Fifteen on an 8 processor box isn't good news, but isn't the end of the world. On a single processor box it's a sign that you've got problems ;)
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It is not a percentage.
http://www.luv.asn.au/overheads/NJG_LUV_2002/luvSlides.html
Simply put the load is how much calculator power your box is doing. I have seen servers that have a value of several hundred load on a day to day basis.
The biggest reason for it being monitored is to watch what is usual and when you see a spike, ascend, descend, etc, you have a history to compare it to. This value will be different for nearly every single server.
Josh Luthman Office: 937-552-2340 Direct: 937-552-2343 1100 Wayne St Suite 1337 Troy, OH 45373
Those who don't understand UNIX are condemned to reinvent it, poorly. --- Henry Spencer
On Wed, Oct 8, 2008 at 5:16 PM, Gavin Leonard <gleonard at progrexion.com>wrote:
I am getting pages from my hobbit server when some of my linux systems are hitting 15 on their load avg. does that equate to something worse than it sounds? Cause 15% load average on a linux system does not seem that bad? Or is it not a percentage?
*Gavin Leonard***
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Director, Systems-Network Engineering
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gleonard at progrexion.com
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It is based on physical processors or cores?
-Gavin
From: Josh Luthman [mailto:josh at imaginenetworksllc.com] Sent: Wednesday, October 08, 2008 3:28 PM To: hobbit at hswn.dk Subject: Re: [hobbit] Load Averages
It is not a percentage.
http://www.luv.asn.au/overheads/NJG_LUV_2002/luvSlides.html
Simply put the load is how much calculator power your box is doing. I have seen servers that have a value of several hundred load on a day to day basis.
The biggest reason for it being monitored is to watch what is usual and when you see a spike, ascend, descend, etc, you have a history to compare it to. This value will be different for nearly every single server.
Josh Luthman Office: 937-552-2340 Direct: 937-552-2343 1100 Wayne St Suite 1337 Troy, OH 45373
Those who don't understand UNIX are condemned to reinvent it, poorly. --- Henry Spencer
On Wed, Oct 8, 2008 at 5:16 PM, Gavin Leonard <gleonard at progrexion.com<mailto:gleonard at progrexion.com>> wrote:
I am getting pages from my hobbit server when some of my linux systems are hitting 15 on their load avg. does that equate to something worse than it sounds? Cause 15% load average on a linux system does not seem that bad? Or is it not a percentage?
Gavin Leonard
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On Wed, Oct 8, 2008 at 22:38, Gavin Leonard <gleonard at progrexion.com> wrote:
It is based on physical processors or cores?
The number of CPU cores in total - so a pair of single core processors and one dual core processor are effectively the same.
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Rob MacGregor Whoever fights monsters should see to it that in the process he doesn't become a monster. Friedrich Nietzsche
On Wed, October 8, 2008 17:27, Josh Luthman wrote:
Simply put the load is how much calculator power your box is doing. I have seen servers that have a value of several hundred load on a day to day basis.
Well, it depends on what sort of work the box is doing, and what your throughput expectations are, but any server at a load average of 200+ is going to have abysmal response times for online users. I've seen that on dedicated mail servers in a spam storm, but when our Oracle database servers go above about 30, we start getting calls from application users. The default alert levels in Hobbit work pretty well for us, letting us check whether anything's going awry or if it's a true spike in demand, before the phones start ringing. I do keep the dedicated Internet-facing sendmail servers at significantly higher thresholds, because mail doesn't necessarily have to move in near real time, and customers are more tolerant of slow delivery than "unable to deliver" warnings and bounces.
Gavin Leonard wrote:
I am getting pages from my hobbit server when some of my linux systems are hitting 15 on their load avg. does that equate to something worse than it sounds? Cause 15% load average on a linux system does not seem that bad? Or is it not a percentage?
Your thinking CPU Utilization. Load Average measures the number of running processes.
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Gavin,
Load average is (more or less) the average length of the run queue for a UNIX-style system (someone once posted a link to a more precise definition on this forum). For your system, a load average value of 15 means that an average of 15 processes are waiting to use the CPU -- a problem for most systems.
If you look at the trends button, you will probably find a CPU utilization graph that shows a split between user, system, and idle CPU usage.
CPU utilization shows how busy the CPU(s) is/are, but load average shows the impact of a busy CPU on the system's workload.
I once had a system that spiked to 200+ in the load average display. This problem was traced to a problem in some multi-threaded code where the threads were going into infinite loops one by one until all of them were locked up. Amazingly enough, the system still responded to interactive usage, but v-e-r-y s-l-o-w-l-y.
GLH
From: Gavin Leonard [mailto:gleonard at progrexion.com]
Sent: Wednesday, October 08, 2008 4:16 PM
To: hobbit at hswn.dk
Subject: [hobbit] Load Averages
I am getting pages from my hobbit server when some of my linuxsystems are hitting 15 on their load avg. does that equate to something worse than it sounds? Cause 15% load average on a linux system does not seem that bad? Or is it not a percentage?
Gavin Leonard
Director, Systems-Network Engineering
T
801-828-1735
F
801-828-1704
E
gleonard at progrexion.com <mailto:gleonard at progrexion.com>
Research | Marketing | Sales Generation
www.progrexion.com <http://www.progrexion.com/>
This email and its contents are confidential. If you are not the intended recipient, delete this email and do not use or disclose the information within this email or its attachments. Thank you.
participants (7)
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gleonard＠progrexion.com
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greg.hubbard＠eds.com
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hobbit＠epperson.homelinux.net
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josh＠imaginenetworksllc.com
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mmccullen＠mwm-tech.com
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rob.macgregor＠gmail.com
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rsmrcina＠wi.rr.com