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

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

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 Neuschäfer <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 Neuschäfer