Re: getloadavg and proc filesystem

[Andrew Miehs <andrew@2sheds.de>]

Actually, I am looking at /proc/stat and that is the problem...

I looked at the implementation of getloadavg to see how 'real  
programmers' used
the proc filesystem. I do not see how the implementation (in glibc)  
is protected
from the kernel changing the data underneath it while it is being  
read....

ie: getloadavg open /proc/loadavg for O_RDONLY
    getloadavg reads the first 4 bytes
    kernel completely updates the file
    getloadavg reads the rest of file.....

And as /proc/stat is bigger, the problem is likely to occur even more  
often?!
Or am i just being stupid?

As for /proc/stat - I am unable to find complete doco for it....
man proc does not state what the last 3 columns in the 'cpu' lines  
are....
Are these iowait and intr (soft) intr (hard)?

Thanks for any help,

Andrew

On Oct 4, 2005, at 6:19 PM, Andy Davidson wrote:
> If you want to monitor just cpu utilisation, the load average isn't  
> going to be a great measure; IO slowdown will 'break' the load  
> average, for example.
>
> You are probably better off looking at /proc/stat.
>
> https://sourceforge.net/projects/loadinfo is an awful hack which  
> might be a good starting point.