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x86: Conditionally update time when ack-ing pending irqs

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On virtual environments, apic_read could take a long time. As a
result, under certain conditions the ack pending loop may exit
without any queued irqs left, but after more than one second. A
warning will be printed needlessly in this case.

If the loop is about to exit regardless of max_loops, don't
update it.

Signed-off-by: Shai Fultheim <shai@scalemp.com>
[ rebased and reworded the commit message]
Signed-off-by: Ido Yariv <ido@wizery.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1334873552-31346-1-git-send-email-ido@wizery.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Shai Fultheim 2012-04-20 01:12:32 +03:00 committed by Ingo Molnar
parent 22042c086c
commit 42fa425043
1 changed files with 7 additions and 5 deletions
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12
arch/x86/kernel/apic/apic.c
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@ -1325,11 +1325,13 @@ void __cpuinit setup_local_APIC(void)
acked);
break;
}
if (cpu_has_tsc) {
rdtscll(ntsc);
max_loops = (cpu_khz << 10) - (ntsc - tsc);
} else
max_loops--;
if (queued) {
if (cpu_has_tsc) {
rdtscll(ntsc);
max_loops = (cpu_khz << 10) - (ntsc - tsc);
} else
max_loops--;
}
} while (queued && max_loops > 0);
WARN_ON(max_loops <= 0);