ubuntu-phone team mailing list archive

[John Lenton <john.lenton@xxxxxxxxxxxxx>]

On Wed, Sep 4, 2013 at 12:25 PM, Thomas Voß <thomas.voss@xxxxxxxxxxxxx> wrote:
>
> True, but to determine the CPU percentage, we would need to have the
> CPU usage of all processes for a certain amount of time available.
> That is, essentially parsing all of proc iiuc. I'm hopefully wrong,
> but if not, could we resort to an approach that just considers the
> per-process user and system CPU time consumed in a given time
> interval?

I might be missing something, but the load average (from
/proc/loadavg) is the overall CPU usage for three given amounts of
time (a minute, five minutes, fifteen minutes). Much faster than
parsing all of proc:

       /proc/loadavg
              The first three fields in this file are  load  average
              figures  giving  the  number  of jobs in the run queue
              (state R) or waiting for disk I/O (state  D)  averaged
              over  1,  5, and 15 minutes.  They are the same as the
              load average numbers given by uptime(1) and other pro‐
              grams.  The fourth field consists of two numbers sepa‐
              rated by a slash (/).  The first of these is the  num‐
              ber  of  currently runnable kernel scheduling entities
              (processes, threads).  The value after  the  slash  is
              the  number  of  kernel  scheduling entities that cur‐
              rently exist on the system.  The fifth  field  is  the
              PID  of  the process that was most recently created on
              the system.

(from 'man proc')