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linuxprocfssar

How is run queue length computed in linux proc filesystem

I'm trying to obtain number of runnable processes from linux kernel. sar -q gives this information readily. However I'm trying to get this value from /proc filesystem. There is no file in /proc that gives this value directly, then how is runq-sz computed. The wiki page http://en.wikipedia.org/wiki/Load_(computing) provides some insight into how run queue length is computed based on ldavg values but it is unclear. Can someone provide more pointers on this. Cheers

Solution

  • As gcla said you cat use 

    cat /proc/loadavg

    to read loadavarage from from kernel - but strictly speaking, it is not a queue length.

    Take a look at 

    grep procs_running /proc/stat

    and

    grep procs_blocked /proc/stat

    First is an actual running queue and second is a number of process blocked on disk IO. Load average is a function from sum of both.