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x86: make poll_idle behave more like the other idle methods

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Make poll_idle() behave more like the other idle methods.

Currently, poll_idle() returns immediately.  The other
idle methods all wait indefinately for some condition
to come true before returning.  poll_idle should emulate
these other methods and also wait for a return condition,
in this case, for need_resched() to become 'true'.

Without this delay the idle loop spends all of its time
in the outer loop that calls poll_idle.  This outer loop,
these days, does real work, some of it under rcu locks.
That work should only be done when idle is entered and
when idle exits, not continuously while idle is spinning.

Signed-off-by: Joe Korty <joe.korty@ccur.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Joe Korty 2008-08-27 10:35:06 -04:00 committed by Ingo Molnar
parent 4c246edd25
commit 2c7e9fd4c6
1 changed files with 2 additions and 1 deletions
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3
arch/x86/kernel/process.c
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@ -185,7 +185,8 @@ static void mwait_idle(void)
static void poll_idle(void)
{
local_irq_enable();
cpu_relax();
while (!need_resched())
cpu_relax();
}
/*