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    SubjectRe: [PATCH] procfs: export context switch counts in /proc/*/stat
    On 12/20/06, David Wragg <david@wragg.org> 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.

    Oh, that'd be great.

    The cumulative ones are still not justified though, and I fear they
    may be 64-bit even on i386. It turns out that an i386 procps spends
    much of its time doing 64-bit division to parse the damn ASCII crap.
    I suppose I could just skip those fields, but generating them isn't
    too cheap and probably I'd get stuck parsing them for some other
    reason -- having them separate is probably a good idea.
    -
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