CPU Utilization, Not Good

6 messages in this thread

list James Wade · Fri, 30 Nov 2007 11:21:25 -0600 ·

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

list Mike Rowell · Fri, 30 Nov 2007 17:51:16 -0000 ·

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

▸ quoted from James Wade

From: James Wade [mailto:user-659655b2ea05@xymon.invalid] 
Sent: 30 November 2007 17:21
To: user-ae9b8668bcde@xymon.invalid
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.

list Greg L Hubbard · Fri, 30 Nov 2007 12:01:39 -0600 ·

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

▸ quoted from James Wade



	From: James Wade [mailto:user-659655b2ea05@xymon.invalid] 
	Sent: Friday, November 30, 2007 11:21 AM
	To: user-ae9b8668bcde@xymon.invalid
	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

list James Wade · Fri, 30 Nov 2007 12:06:44 -0600 ·

I thought I'd give some more information.

I'm using solaris, and cpu utilization used vmstat.

 
If I do a sar I get this:

 
10:10:00      23       5       6      66

10:20:00      46       5       4      44

10:30:00      69       7       7      18

10:40:00      76       7       4      13

10:50:01      81       6       2      11

11:00:00      69       7       4      20

11:10:01      71       9       5      15

11:20:01      88       7       1       4

 
Average       23       5       6      66

 
Notice that cpu utilization from about 10:30 to 11:20 is

high. 

 
However, with Hobbit, I get a solid 23% average for everything.
the hobbit-client-sunos.sh uses:  vmstat 300 2 which gives met this:

 
$ vmstat 300 2

 kthr      memory            page            disk          faults      cpu

 r b w   swap  free  re  mf pi po fr de sr s0 s3 s6 s9   in   sy   cs us sy
id

 0 0 0 166920152 16811328 878 1814 1902 55 55 0 0 0 0 0 0 1755 3374 6188 16
4 80

 0 0 0 166919832 16811024 878 1814 1902 55 55 0 0 0 0 0 0 1756 3376 6188 16
4 80

 
Notice that a 5 minute average from vmstat shows 80% idle, yet the sar above
doesn't show that.

 
Is there anyway to get Hobbit to use sar for CPU utilization instead of
vmstat on solaris?

 
Thanks.James

▸ quoted from James Wade

From: James Wade [mailto:user-659655b2ea05@xymon.invalid] 
Sent: Friday, November 30, 2007 11:21 AM
To: 'user-ae9b8668bcde@xymon.invalid'
Subject: 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

list James Wade · Fri, 30 Nov 2007 12:13:31 -0600 ·

Added the sar descriptions

▸ quoted from James Wade

Thanks.James

From: James Wade [mailto:user-659655b2ea05@xymon.invalid] 
Sent: Friday, November 30, 2007 12:07 PM
To: user-ae9b8668bcde@xymon.invalid
Subject: [hobbit] RE: CPU Utilization, Not Good

I thought I'd give some more information.

I'm using solaris, and cpu utilization used vmstat.

If I do a sar I get this:


             %usr    %sys    %wio   %idle

▸ quoted from James Wade


10:10:00      23       5       6      66

10:20:00      46       5       4      44

10:30:00      69       7       7      18

10:40:00      76       7       4      13

10:50:01      81       6       2      11

11:00:00      69       7       4      20

11:10:01      71       9       5      15

11:20:01      88       7       1       4

 
Average       23       5       6      66

 
Notice that cpu utilization from about 10:30 to 11:20 is

high. 

 
However, with Hobbit, I get a solid 23% average for everything.
the hobbit-client-sunos.sh uses:  vmstat 300 2 which gives met this:

 
$ vmstat 300 2

 kthr      memory            page            disk          faults      cpu

 r b w   swap  free  re  mf pi po fr de sr s0 s3 s6 s9   in   sy   cs us sy
id

 0 0 0 166920152 16811328 878 1814 1902 55 55 0 0 0 0 0 0 1755 3374 6188 16
4 80

 0 0 0 166919832 16811024 878 1814 1902 55 55 0 0 0 0 0 0 1756 3376 6188 16
4 80

 
Notice that a 5 minute average from vmstat shows 80% idle, yet the sar above
doesn't show that.

 
Is there anyway to get Hobbit to use sar for CPU utilization instead of
vmstat on solaris?

 
Thanks.James

 
From: James Wade [mailto:user-659655b2ea05@xymon.invalid] 
Sent: Friday, November 30, 2007 11:21 AM
To: 'user-ae9b8668bcde@xymon.invalid'
Subject: 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

list Henrik Størner · Fri, 30 Nov 2007 22:29:46 +0100 ·

▸ quoted from 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 :-)

▸ quoted from James Wade

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

CPU Utilization, Not Good 🔗 link

CPU Utilization, Not Good