Hi,
I've asked this several times, but I really have not received
a good answer. Hobbit doesn't really seem to monitor cpu
utilization correctly.
For example, I can look at the load, login to the box, and then
run top. Top shows that cpu utilization is at 100%, 0% idle time.
However, the "trends" utilization graph shows 20% cpu utilization.
Can someone tell me why?
Thanks..James
James Wade
James,
What box are we talking about here, architecture and OS/version.
I know that Top doesn't run accurately for certain bits iowait being the most common one on Solaris 10 anymore due to changes in the underlying structures it uses.
Regards,
Mike
From: James Wade [mailto:jkwade at futurefrontiers.com] Sent: 30 November 2007 17:21 To: hobbit at hswn.dk Subject: [hobbit] CPU Utilization, Not Good
Hi,
I've asked this several times, but I really have not received
a good answer. Hobbit doesn't really seem to monitor cpu
utilization correctly.
For example, I can look at the load, login to the box, and then
run top. Top shows that cpu utilization is at 100%, 0% idle time.
However, the "trends" utilization graph shows 20% cpu utilization.
Can someone tell me why?
Thanks....James
James Wade
This email has been scanned for all viruses by the MessageLabs service.
This email has been scanned for all viruses by the MessageLabs service.
The agent may be using top to get an average across the entire sample period (300 seconds). When you run top interactively you are seeing a shorter sample. But I think there is some "smoothing" in top to begin with. To add some extra zest, the RRD tool also applies some normalization of its own to the data as it comes in.
To really answer your question, though, you should look at the source to see what parameters Hobbit is using for top, then you can compare the "raw" output with what is getting graphed.
GLH
From: James Wade [mailto:jkwade at futurefrontiers.com]
Sent: Friday, November 30, 2007 11:21 AM
To: hobbit at hswn.dk
Subject: [hobbit] CPU Utilization, Not Good
Hi,
I've asked this several times, but I really have not received
a good answer. Hobbit doesn't really seem to monitor cpu
utilization correctly.
For example, I can look at the load, login to the box, and then
run top. Top shows that cpu utilization is at 100%, 0% idletime.
However, the "trends" utilization graph shows 20% cpuutilization.
Can someone tell me why?
Thanks....James
James Wade
On Fri, Nov 30, 2007 at 11:21:25AM -0600, James Wade wrote:
I've asked this several times, but I really have not received a good answer. Hobbit doesn't really seem to monitor cpu utilization correctly.
Hobbit uses the system's "vmstat" command to determine how much the CPU is being used. So the blame should go to your vmstat tool - or your interpretation of the data :-)
For example, I can look at the load, login to the box, and then run top. Top shows that cpu utilization is at 100%, 0% idle time.
However, the "trends" utilization graph shows 20% cpu utilization.
Hobbit monitors the load as an average over 5 minutes. "top" - at least when used interactively - has a sample period of a few seconds. I have some systems where "top" will ALWAYS show the cpu as 100% busy, because "top" is gobbling up all of the cpu time for itself ....
If you want to see things the way Hobbit does, run "vmstat 2 300", wait for it to complete (5 minutes), and look at the cpu-utilisation reported on the last line.
Henrik
participants (4)
-
greg.hubbard＠eds.com
-
henrik＠hswn.dk
-
jkwade＠futurefrontiers.com
-
Mike.Rowell＠Rightmove.co.uk