[Xen-changelog] Manual update for rcu changes in 2.0-testing.

[BitKeeper Bot <riel@xxxxxxxxxxx>]

ChangeSet 1.1593, 2005/05/30 11:35:55+01:00, kaf24@xxxxxxxxxxxxxxxxxxxx

        Manual update for rcu changes in 2.0-testing.
        Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>



 time.c |   78 ++++++++++++++++++++++++++++++-----------------------------------
 1 files changed, 36 insertions(+), 42 deletions(-)


diff -Nru a/linux-2.6.11-xen-sparse/arch/xen/i386/kernel/time.c 
b/linux-2.6.11-xen-sparse/arch/xen/i386/kernel/time.c
--- a/linux-2.6.11-xen-sparse/arch/xen/i386/kernel/time.c       2005-05-30 
07:03:41 -04:00
+++ b/linux-2.6.11-xen-sparse/arch/xen/i386/kernel/time.c       2005-05-30 
07:03:41 -04:00
@@ -689,58 +689,52 @@
        (void)setup_irq(per_cpu(timer_irq, 0), &irq_timer);
 }
 
-/* Convert jiffies to system time. Call with xtime_lock held for reading. */
-static inline u64 __jiffies_to_st(unsigned long j) 
+/* Convert jiffies to system time. */
+static inline u64 jiffies_to_st(unsigned long j) 
 {
-       long delta = j - jiffies;
-       /* NB. The next check can trigger in some wrap-around cases, but
-        * that's ok -- we'll just end up with a shorter timeout. */
-       if (delta < 1)
-               delta = 1;
-       return processed_system_time + (delta * NS_PER_TICK);
+       unsigned long seq;
+       long delta;
+       u64 st;
+
+       do {
+               seq = read_seqbegin(&xtime_lock);
+               delta = j - jiffies;
+               /* NB. The next check can trigger in some wrap-around cases,
+                * but that's ok: we'll just end up with a shorter timeout. */
+               if (delta < 1)
+                       delta = 1;
+               st = processed_system_time + (delta * NS_PER_TICK);
+       } while (read_seqretry(&xtime_lock, seq));
+
+       return st;
 }
 
 /*
- * This function works out when the the next timer function has to be
- * executed (by looking at the timer list) and sets the Xen one-shot
- * domain timer to the appropriate value. This is typically called in
- * cpu_idle() before the domain blocks.
- * 
- * The function returns a non-0 value on error conditions.
- * 
- * It must be called with interrupts disabled.
+ * stop_hz_timer / start_hz_timer - enter/exit 'tickless mode' on an idle cpu
+ * These functions are based on implementations from arch/s390/kernel/time.c
  */
-int set_timeout_timer(void)
+void stop_hz_timer(void)
 {
-       u64 alarm = 0;
-       int ret = 0;
+       unsigned int cpu = smp_processor_id();
        unsigned long j;
-#ifdef CONFIG_SMP
-       unsigned long seq;
-#endif
 
-       /*
-        * This is safe against long blocking (since calculations are
-        * not based on TSC deltas). It is also safe against warped
-        * system time since suspend-resume is cooperative and we
-        * would first get locked out.
-        */
-#ifdef CONFIG_SMP
-       do {
-               seq = read_seqbegin(&xtime_lock);
+       /* s390 does this /before/ checking rcu_pending(). We copy them. */
+       cpu_set(cpu, nohz_cpu_mask);
+
+       /* Leave ourselves in 'tick mode' if rcu or softirq pending. */
+       if (rcu_pending(cpu) || local_softirq_pending()) {
+               cpu_clear(cpu, nohz_cpu_mask);
                j = jiffies + 1;
-               alarm = __jiffies_to_st(j);
-       } while (read_seqretry(&xtime_lock, seq));
-#else
-       j = next_timer_interrupt();
-       alarm = __jiffies_to_st(j);
-#endif
-
-       /* Failure is pretty bad, but we'd best soldier on. */
-       if ( HYPERVISOR_set_timer_op(alarm) != 0 )
-               ret = -1;
+       } else {
+               j = next_timer_interrupt();
+       }
 
-       return ret;
+       BUG_ON(HYPERVISOR_set_timer_op(jiffies_to_st(j)) != 0);
+}
+
+void start_hz_timer(void)
+{
+       cpu_clear(smp_processor_id(), nohz_cpu_mask);
 }
 
 void time_suspend(void)

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