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    SubjectRe: [PATCH] procfs: export context switch counts in /proc/*/stat
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    On Wed, 2006-12-20 at 13:20 +0000, David Wragg wrote:
    > "Albert Cahalan" <acahalan@gmail.com> writes:
    > > On Mon, Dec 18, 2006 at 11:50:08PM +0000, David Wragg wrote:
    > >> This patch (against 2.6.19/2.6.19.1) adds the four context
    > >> switch values (voluntary context switches, involuntary
    > >> context switches, and the same values accumulated from
    > >> terminated child processes) to the end of /proc/*/stat,
    > >> similarly to min_flt, maj_flt and the time used values.
    > >
    > > Hmmm, OK, do people have a use for these values?
    >
    > My reason for writing the patch was to track which processes are
    > active (i.e. got scheduled to run) by polling these context switch
    > values. The time used values are not a reliable way to detect process
    > activity on fast machines. So for example, when sorting by %CPU, top
    > often shows many processes using 0% CPU, despite the fact that these
    > processes are running occasionally. If top sorted by (%CPU, context
    > switch count delta), it might give a more useful display of which
    > processes are active on the system.


    if all you care is the number of context switches, you can use the
    following system tap script as well:

    http://www.fenrus.org/cstop.stp


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