Messages in this thread | | | Date | Wed, 20 Dec 2006 12:36:23 -0500 | From | "Albert Cahalan" <> | Subject | Re: [PATCH] procfs: export context switch counts in /proc/*/stat |
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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. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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