[tip:x86/apic] x86: Conditionally update time when ack-ing pending irqs
From: tip-bot for Shai Fultheim
Date: Tue May 08 2012 - 00:25:09 EST
Commit-ID: 42fa4250436304d4650fa271f37671f6cee24e08
Gitweb: http://git.kernel.org/tip/42fa4250436304d4650fa271f37671f6cee24e08
Author: Shai Fultheim <shai@xxxxxxxxxxx>
AuthorDate: Fri, 20 Apr 2012 01:12:32 +0300
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Mon, 7 May 2012 16:25:28 +0200
x86: Conditionally update time when ack-ing pending irqs
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@xxxxxxxxxxx>
[ rebased and reworded the commit message]
Signed-off-by: Ido Yariv <ido@xxxxxxxxxx>
Acked-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1334873552-31346-1-git-send-email-ido@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
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 edc2448..3beab62 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);
--
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