Re: linux-2.6.0-test2: Never using pm_idle (CPU wasting power)

From: Robert Love (rml@tech9.net)
Date: Thu Jul 31 2003 - 17:58:57 EST


On Thu, 2003-07-31 at 15:45, Roger Larsson wrote:

> This smells preemptive kernel, correct?

Doesn't look like anything specific to kernel preemption to me.

But if need_resched() is never zero, the while loop fails, and
schedule() _should_ be reached. So something is fishy here. Looking at
it the other way, however, if schedule() is never called, then
need_resched() will remain non-zero forever. Maybe you mean
need_resched() is never non-zero, i.e., it is always zero?

I think the problem is that there is a race between whatever you are
saying ACPI is doing with pm_idle and the setting of idle. Actually,
that is exactly what you are saying :)

Your fix smells exactly of that. Maybe have APCI set need_resched, so
the loop flips over again?

        Robert Love

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