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Subject[PATCH] x86: Conditionally update time when ack-ing pending irqs
Date
From: Shai Fultheim <shai@scalemp.com>

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>
[ido@wizery.com: rebased and reworded the commit message]
Signed-off-by: Ido Yariv <ido@wizery.com>
---
arch/x86/kernel/apic/apic.c | 12 +++++++-----
1 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 11544d8..f0330f2 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -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);

--
1.7.7.6


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