How to get cpu utilization through code with least overhead?

How to get cpu utilization through code with least overhead?

[Vaibhav Jain]

Hi,

I need to write code to get and record the cpu utilization in certain
interval with the least overhead.
Could anybody please advise me on how to proceed ? I tried looking at the
code for "top" command to see
how it works but couldn't figure out much.
I don't want to write script that uses commands and pulls out the results as
I want the overhead to be as small as possible.

Thanks
Vaibhav Jain
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How to get cpu utilization through code with least overhead?

[Mulyadi Santosa]

On Fri, Jul 29, 2011 at 00:38, Vaibhav Jain <vjoss197@gmail.com> wrote:
> Hi,
>
> I need to write code to get and record the cpu utilization in certain
> interval with the least overhead.

try to derive them from /proc/loadavg or /proc/stat...

-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com

How to get cpu utilization through code with least overhead?

[Vaibhav Jain]

Thanks! Just curious to know if  this is how "top" does it.

Thanks
Vaibhav Jain

On Thu, Jul 28, 2011 at 10:45 AM, Mulyadi Santosa <mulyadi.santosa@gmail.com
> wrote:

> On Fri, Jul 29, 2011 at 00:38, Vaibhav Jain <vjoss197@gmail.com> wrote:
> > Hi,
> >
> > I need to write code to get and record the cpu utilization in certain
> > interval with the least overhead.
>
> try to derive them from /proc/loadavg or /proc/stat...
>
> --
> regards,
>
> Mulyadi Santosa
> Freelance Linux trainer and consultant
>
> blog: the-hydra.blogspot.com
> training: mulyaditraining.blogspot.com
>
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How to get cpu utilization through code with least overhead?

[Vaibhav Jain]

Hi,

Is there any other way to do this? If I need to write a kernel module that
needs to get cpu utilization
should I still use proc/stat ? Is there a kernel function that can be used
in a module ?

Thanks
Vaibhav Jain

On Thu, Jul 28, 2011 at 10:51 AM, Vaibhav Jain <vjoss197@gmail.com> wrote:

> Thanks! Just curious to know if  this is how "top" does it.
>
> Thanks
> Vaibhav Jain
>
>   On Thu, Jul 28, 2011 at 10:45 AM, Mulyadi Santosa <
> mulyadi.santosa at gmail.com> wrote:
>
>> On Fri, Jul 29, 2011 at 00:38, Vaibhav Jain <vjoss197@gmail.com> wrote:
>> > Hi,
>> >
>> > I need to write code to get and record the cpu utilization in certain
>> > interval with the least overhead.
>>
>> try to derive them from /proc/loadavg or /proc/stat...
>>
>> --
>> regards,
>>
>> Mulyadi Santosa
>> Freelance Linux trainer and consultant
>>
>> blog: the-hydra.blogspot.com
>> training: mulyaditraining.blogspot.com
>>
>
>
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How to get cpu utilization through code with least overhead?

[Raghu Udiyar]

On Fri, Jul 29, 2011 at 5:26 AM, Vaibhav Jain <vjoss197@gmail.com> wrote:

> Hi,
>
> Is there any other way to do this? If I need to write a kernel module that
> needs to get cpu utilization
> should I still use proc/stat ? Is there a kernel function that can be used
> in a module ?
>
> Thanks
> Vaibhav Jain
>

The kernel writes all cpu metrics and more to /proc/stat. I/O data goes to
/proc/diskstat and memory to /proc/vmstat.  Top and other tools interpret
the counters written to these files.

You can also look at hardware performance counters, as used by the perf
utility.
--
Raghu S Udiyar
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How to get cpu utilization through code with least overhead?

[Jonathan Neuschäfer]

On Thu, Jul 28, 2011 at 04:56:16PM -0700, Vaibhav Jain wrote:
> Hi,
> 
> Is there any other way to do this? If I need to write a kernel module that
> needs to get cpu utilization
> should I still use proc/stat ? Is there a kernel function that can be used
> in a module ?

To get the information that's shown in /proc/stat, I'd suggest having a
look at fs/proc/stat.c in the kernel tree.

HTH,
	Jonathan Neusch?fer

How to get cpu utilization through code with least overhead?

[Vaibhav Jain]

Thanks !!
I looked at the code for top command again and I could see /proc/stat being
used. So I guess
that should be the best way to do it.


On Fri, Jul 29, 2011 at 12:15 PM, Jonathan Neusch?fer <j.neuschaefer@gmx.net
> wrote:

> On Thu, Jul 28, 2011 at 04:56:16PM -0700, Vaibhav Jain wrote:
> > Hi,
> >
> > Is there any other way to do this? If I need to write a kernel module
> that
> > needs to get cpu utilization
> > should I still use proc/stat ? Is there a kernel function that can be
> used
> > in a module ?
>
> To get the information that's shown in /proc/stat, I'd suggest having a
> look at fs/proc/stat.c in the kernel tree.
>
> HTH,
>         Jonathan Neusch?fer
>
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