CPU/disk usage

CPU/disk usage

[Adam Dyga]

Hello,

What's the best way to:
1. Get the percent cpu usage (as in top)
2. Get disk activity (eg. number of bytes read/written from/to disk 
during some period of time).

Ad1) I know I could find the cpu usage in top sources, but unfortunately 
I don't have enough time
to do it currently - maybe some of you did this already.
There is sysinfo() system call that returns average loads during the 
last 1, 5, and 15
minutes but average load, AFAIK, is a average number of tasks waiting 
for cpu, so it's not
exactly what I want.

Cheers
AD

Re: CPU/disk usage

[Glynn Clements]

Adam Dyga wrote:

> What's the best way to:
> 1. Get the percent cpu usage (as in top)

The way that ps does it is to obtain the process start time and amount
of user and system time used from /proc/<pid>/stat, and the number of
seconds since boot from /proc/uptime, then compute the CPU usage as
the ratio of the total time used (user + system) to the time the
process has been running (system uptime - process start time).

Note that this gives the average CPU usage over the lifetime of the
process. If you want a current figure, measure the change in the total
usage over a given interval and divide by the interval.

-- 
Glynn Clements <glynn@gclements.plus.com>

Re: CPU/disk usage

[Akbar Ali]

Why not just take a quick look at the top source code
?
btw, if you find out tell me, cause i'm intersted in
that data as well..

--- Adam Dyga <adeon@tlen.pl> wrote:
> Hello,
> 
> What's the best way to:
> 1. Get the percent cpu usage (as in top)
> 2. Get disk activity (eg. number of bytes
> read/written from/to disk 
> during some period of time).
> 
> Ad1) I know I could find the cpu usage in top
> sources, but unfortunately 
> I don't have enough time
> to do it currently - maybe some of you did this
> already.
> There is sysinfo() system call that returns average
> loads during the 
> last 1, 5, and 15
> minutes but average load, AFAIK, is a average number
> of tasks waiting 
> for cpu, so it's not
> exactly what I want.
> 
> Cheers
> AD
> -
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