Messages in this thread | | | From | Peter Chubb <> | Date | Wed, 27 Aug 2003 11:52:52 +1000 | Subject | Re: [PATCH] 2.6.0-test4 -- add context switch counters |
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>>>>> "Mike" == Mike Fedyk <mfedyk@matchmail.com> writes:
Mike> On Tue, Aug 26, 2003 at 06:18:07PM -0700, Andrew Morton wrote: >> Peter Chubb <peterc@gelato.unsw.edu.au> wrote: >> > >> > Currently, the context switch counters reported by getrusage() >> are > always zero. The appended patch adds fields to struct >> task_struct to > count context switches, and adds code to do the >> counting. >> > >> > The patch adds 4 longs to struct task struct, and a single >> addition to > the fast path in schedule(). >> >> OK... Why is this useful? A bit of googling doesn't show much >> interest in it. >> >> What apps should be reporting this info? /usr/bin/time?
Mike> Voluntary context switches: 0
Mike> How can you have voluntary context switches in a preemptive Mike> environment?
A voluntary context switch is where a task gives up the processor (e.g., by going to sleep, or by calling sched_yield()).
An involuntary context switch is where a task is preempted by some other task.
(Another figure-of-merit might be how many times the process is interrupted by a hardware interrupt)
-- Dr Peter Chubb http://www.gelato.unsw.edu.au peterc AT gelato.unsw.edu.au You are lost in a maze of BitKeeper repositories, all slightly different. - 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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