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[Xen-devel] [PATCH] linux: fix condition for entering tickless state

To: <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: [Xen-devel] [PATCH] linux: fix condition for entering tickless state
From: "Jan Beulich" <jbeulich@xxxxxxxxxx>
Date: Fri, 09 Mar 2007 16:54:17 +0000
Delivery-date: Fri, 09 Mar 2007 08:53:06 -0800
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I noticed that timer interrupts were running at full rate regardless
of whether the system was idle.
softlockup_get_next_event() must return the maximum of zero and the
delta to the next event, not the minimum (which is always zero or
negative, yielding zero or a very large positive number as return

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

Index: ./patches/linux-2.6.18/softlockup-no-idle-hz.patch
--- ./patches/linux-2.6.18/softlockup-no-idle-hz.patch
+++ ./patches/linux-2.6.18/softlockup-no-idle-hz.patch
@@ -34,7 +34,7 @@ unsigned long softlockup_get_next_event(
 +                      !per_cpu(watchdog_task, this_cpu))
 +              return MAX_JIFFY_OFFSET;
-+      return min_t(long, 0, touch_timestamp + HZ - jiffies);
++      return max_t(long, 0, touch_timestamp + HZ - jiffies);

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