[PATCH] tick-management: dyntick / highres functionality

With Ingo Molnar <mingo@elte.hu>

Add functions to provide dynamic ticks and high resolution timers.  The code
which keeps track of jiffies and handles the long idle periods is shared
between tick based and high resolution timer based dynticks.  The dyntick
functionality can be disabled on the kernel commandline.  Provide also the
infrastructure to support high resolution timers.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 12 insertions, 3 deletions

diff --git a/kernel/softirq.c b/kernel/softirq.c
index 14e1a14f94d2..8b75008e2bd8 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -17,6 +17,7 @@
 #include <linux/kthread.h>
 #include <linux/rcupdate.h>
 #include <linux/smp.h>
+#include <linux/tick.h>
 
 #include <asm/irq.h>
 /*
@@ -278,9 +279,11 @@ EXPORT_SYMBOL(do_softirq);
  */
 void irq_enter(void)
 {
-        account_system_vtime(current);
-        add_preempt_count(HARDIRQ_OFFSET);
-        trace_hardirq_enter();
+        __irq_enter();
+#ifdef CONFIG_NO_HZ
+        if (idle_cpu(smp_processor_id()))
+                tick_nohz_update_jiffies();
+#endif
 }
 
 #ifdef __ARCH_IRQ_EXIT_IRQS_DISABLED
@@ -299,6 +302,12 @@ void irq_exit(void)
         sub_preempt_count(IRQ_EXIT_OFFSET);
         if (!in_interrupt() && local_softirq_pending())
                 invoke_softirq();
+
+#ifdef CONFIG_NO_HZ
+        /* Make sure that timer wheel updates are propagated */
+        if (!in_interrupt() && idle_cpu(smp_processor_id()) && !need_resched())
+                tick_nohz_stop_sched_tick();
+#endif
         preempt_enable_no_resched();
 }