[PATCH] Run timers as softirqs, not tasklets

The timer code is attempting to replicate the softirq characteristics at
the tasklet level, which is a little pointless.  This patch converts
timers to be a first-class softirq citizen.

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 946a6229e4cd999d192e144bc15ba03ba37760db..21023d2807e8456003007ff0fb56de4d31694d89 100644 (file)
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -44,6 +44,7 @@ extern void free_irq(unsigned int, void *);
 enum
 {
        HI_SOFTIRQ=0,
+       TIMER_SOFTIRQ,
        NET_TX_SOFTIRQ,
        NET_RX_SOFTIRQ,
        SCSI_SOFTIRQ,

diff --git a/kernel/timer.c b/kernel/timer.c
index ffc50df1a072760ded9963f234d3427b67c25777..19e4296c72bddbc5aef57e88df45380c35bf1e53 100644 (file)
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -66,9 +66,6 @@ typedef struct tvec_t_base_s tvec_base_t;
 /* Fake initialization */
 static DEFINE_PER_CPU(tvec_base_t, tvec_bases) = { SPIN_LOCK_UNLOCKED };
 
-/* Fake initialization needed to avoid compiler breakage */
-static DEFINE_PER_CPU(struct tasklet_struct, timer_tasklet) = { NULL };
-
 static void check_timer_failed(timer_t *timer)
 {
        static int whine_count;
@@ -766,9 +763,9 @@ rwlock_t xtime_lock __cacheline_aligned_in_smp = RW_LOCK_UNLOCKED;
 unsigned long last_time_offset;
 
 /*
- * This function runs timers and the timer-tq in softirq context.
+ * This function runs timers and the timer-tq in bottom half context.
  */
-static void run_timer_tasklet(unsigned long data)
+static void run_timer_softirq(struct softirq_action *h)
 {
        tvec_base_t *base = &per_cpu(tvec_bases, smp_processor_id());
 
@@ -781,7 +778,7 @@ static void run_timer_tasklet(unsigned long data)
  */
 void run_local_timers(void)
 {
-       tasklet_hi_schedule(&per_cpu(timer_tasklet, smp_processor_id()));
+       raise_softirq(TIMER_SOFTIRQ);
 }
 
 /*
@@ -1140,7 +1137,6 @@ static void __devinit init_timers_cpu(int cpu)
        }
        for (j = 0; j < TVR_SIZE; j++)
                INIT_LIST_HEAD(base->tv1.vec + j);
-       tasklet_init(&per_cpu(timer_tasklet, cpu), run_timer_tasklet, 0UL);
 }
        
 static int __devinit timer_cpu_notify(struct notifier_block *self, 
@@ -1167,4 +1163,5 @@ void __init init_timers(void)
        timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE,
                                (void *)(long)smp_processor_id());
        register_cpu_notifier(&timers_nb);
+       open_softirq(TIMER_SOFTIRQ, run_timer_softirq, NULL);
 }