Messages in this thread | | | From | Roger Larsson <> | Subject | Re: linux-2.6.0-test2: Never using pm_idle (CPU wasting power) | Date | Fri, 1 Aug 2003 00:45:08 +0200 |
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On Thursday 31 July 2003 15.07, Christian Vogel wrote: > Hi, > > on a Thinkpad 600X I noticed the CPU getting very hot. It turned > out that pm_idle was never called (which invokes the ACPI pm_idle > call in this case) and default_idle was used instead. > > /* arch/i386/kernel/process.c, line 723 */ > void cpu_idle (void) > { > /* endless idle loop with no priority at all */ > while (1) { > void (*idle)(void) = pm_idle; > if (!idle) > idle = default_idle; /* once on bootup */ > irq_stat[smp_processor_id()].idle_timestamp = jiffies; > while (!need_resched()) > idle(); > schedule(); /* never reached */ > } > } > > The schedule() is never reached (need_resched() is never 0) and > so the idle-variable is not updated. pm_idle is NULL on the > first call to cpu_idle on this thinkpad, and so I stay idling > in the default_idle()-function. >
This smells preemptive kernel, correct?
> By moving the "void *idle = pm_idle; if(!idle)..." in the inner > while()-loop the notebook calls pm_idle (as it get's updated by ACPI) > and stays cool. >
/RogerL
-- Roger Larsson Skellefteå Sweden - 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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