getProcessCPULoad returns different CPU percentage as comparead to top linux command

[Nikhil Agarwal]

Hi David,
		Thanks for your reply , It seems top command  also uses /proc/stat to do the magic .Reading a similar issue for top vs another monitor tool on
https://medium.com/@yogita088/how-to-calculate-cpu-usage-proc-stat-vs-top-e74f99f02d08  , What is the duration for which getProcessCPUload reports CPU utilisation , is it from system start time or 1 sec or x seconds ? It is configurable in top command as -d parameter. This might help to discover difference btw top vs getprocesscpuload

regards
Nikhil


-----Original Message-----
From: David Holmes <david.holmes at oracle.com> 
Sent: 06 November 2023 10:58
To: Nikhil Agarwal <nikhil.a.agarwal at oracle.com>; serviceability-dev at openjdk.org
Subject: Re: getProcessCPULoad returns different CPU percentage as comparead to top linux command

Hi,

On 3/11/2023 11:50 pm, Nikhil Agarwal wrote:
> Hi All,
> 
>                getProcessCPULoad returns different CPU percentage as 
> compared to top linux command intermittently . Does it supposed to 
> returned same data as top command always .  Should the 
> getProcessCPULoad value be same as  top/number of cpus always ?

I've no idea how top calculates what it does. The VM reads the first line of /proc/stat to get the various tick counters.

HTH.

David

> regards
> 
> Nikhil
>