[Xen-changelog] [linux-2.6.18-xen] Imported patch softlockup-no-idle-hz.patch from xen-unstable.hg 15200:bd3d6b4c52ec

["Xen patchbot-linux-2.6.18-xen" <patchbot-linux-2.6.18-xen@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Ian Campbell <ian.campbell@xxxxxxxxxxxxx>
# Date 1180947924 -3600
# Node ID 61ed8662b69cc65aeb3371bcc6bc13d616999cd1
# Parent  139f7610ddf64d9eb149bfef48bc9ead83b54520
Imported patch softlockup-no-idle-hz.patch from xen-unstable.hg 
15200:bd3d6b4c52ec
---
 include/linux/sched.h |    5 +++++
 kernel/softlockup.c   |   13 +++++++++++++
 kernel/timer.c        |    4 +++-
 3 files changed, 21 insertions(+), 1 deletion(-)

diff -r 139f7610ddf6 -r 61ed8662b69c include/linux/sched.h
--- a/include/linux/sched.h     Mon Jun 04 10:05:24 2007 +0100
+++ b/include/linux/sched.h     Mon Jun 04 10:05:24 2007 +0100
@@ -211,10 +211,15 @@ extern void scheduler_tick(void);
 extern void scheduler_tick(void);
 
 #ifdef CONFIG_DETECT_SOFTLOCKUP
+extern unsigned long softlockup_get_next_event(void);
 extern void softlockup_tick(void);
 extern void spawn_softlockup_task(void);
 extern void touch_softlockup_watchdog(void);
 #else
+static inline unsigned long softlockup_get_next_event(void)
+{
+       return MAX_JIFFY_OFFSET;
+}
 static inline void softlockup_tick(void)
 {
 }
diff -r 139f7610ddf6 -r 61ed8662b69c kernel/softlockup.c
--- a/kernel/softlockup.c       Mon Jun 04 10:05:24 2007 +0100
+++ b/kernel/softlockup.c       Mon Jun 04 10:05:24 2007 +0100
@@ -39,6 +39,19 @@ void touch_softlockup_watchdog(void)
        __raw_get_cpu_var(touch_timestamp) = jiffies;
 }
 EXPORT_SYMBOL(touch_softlockup_watchdog);
+
+unsigned long softlockup_get_next_event(void)
+{
+       int this_cpu = smp_processor_id();
+       unsigned long touch_timestamp = per_cpu(touch_timestamp, this_cpu);
+
+       if (per_cpu(print_timestamp, this_cpu) == touch_timestamp ||
+               did_panic ||
+                       !per_cpu(watchdog_task, this_cpu))
+               return MAX_JIFFY_OFFSET;
+
+       return max_t(long, 0, touch_timestamp + HZ - jiffies);
+}
 
 /*
  * This callback runs from the timer interrupt, and checks
diff -r 139f7610ddf6 -r 61ed8662b69c kernel/timer.c
--- a/kernel/timer.c    Mon Jun 04 10:05:24 2007 +0100
+++ b/kernel/timer.c    Mon Jun 04 10:05:24 2007 +0100
@@ -485,7 +485,9 @@ unsigned long next_timer_interrupt(void)
                if (hr_expires < 3)
                        return hr_expires + jiffies;
        }
-       hr_expires += jiffies;
+       hr_expires = min_t(unsigned long,
+                          softlockup_get_next_event(),
+                          hr_expires) + jiffies;
 
        base = __get_cpu_var(tvec_bases);
        spin_lock(&base->lock);

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