- Separate out show_stack changes into own patch.

[linux-flexiantxendom0-3.2.10.git] / arch / ia64 / kernel / smpboot.c

diff --git a/arch/ia64/kernel/smpboot.c b/arch/ia64/kernel/smpboot.c
index dfd8ffd..8c183cd 100644 (file)
--- a/arch/ia64/kernel/smpboot.c
+++ b/arch/ia64/kernel/smpboot.c
@@ -192,6 +192,7 @@ ia64_sync_itc (unsigned int master)
 {
        long i, delta, adj, adjust_latency = 0, done = 0;
        unsigned long flags, rt, master_time_stamp, bound;
+       extern void ia64_cpu_local_tick (void);
 #if DEBUG_ITC_SYNC
        struct {
                long rt;        /* roundtrip time */
@@ -246,6 +247,16 @@ ia64_sync_itc (unsigned int master)
 
        printk(KERN_INFO "CPU %d: synchronized ITC with CPU %u (last diff %ld cycles, "
               "maxerr %lu cycles)\n", smp_processor_id(), master, delta, rt);
+
+       /*
+        * Check whether we sync'd the itc ahead of the next timer interrupt.  If so, just
+        * reset it.
+        */
+       if (time_after(ia64_get_itc(), local_cpu_data->itm_next)) {
+               Dprintk("CPU %d: oops, jumped a timer tick; resetting timer.\n",
+                       smp_processor_id());
+               ia64_cpu_local_tick();
+       }
 }
 
 /*
@@ -279,15 +290,6 @@ smp_callin (void)
 
        smp_setup_percpu_timer();
 
-       if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) {
-               /*
-                * Synchronize the ITC with the BP
-                */
-               Dprintk("Going to syncup ITC with BP.\n");
-
-               ia64_sync_itc(0);
-       }
-
        /*
         * Get our bogomips.
         */
@@ -310,6 +312,18 @@ smp_callin (void)
        local_irq_enable();
        calibrate_delay();
        local_cpu_data->loops_per_jiffy = loops_per_jiffy;
+
+       if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) {
+               /*
+                * Synchronize the ITC with the BP.  Need to do this after irqs are
+                * enabled because ia64_sync_itc() calls smp_call_function_single(), which
+                * calls spin_unlock_bh(), which calls spin_unlock_bh(), which calls
+                * local_bh_enable(), which bugs out if irqs are not enabled...
+                */
+               Dprintk("Going to syncup ITC with BP.\n");
+               ia64_sync_itc(0);
+       }
+
        /*
         * Allow the master to continue.
         */
@@ -394,13 +408,26 @@ do_boot_cpu (int sapicid, int cpu)
        return 0;
 }
 
-unsigned long cache_decay_ticks;       /* # of ticks an idle task is considered cache-hot */
+static int __init
+decay (char *str)
+{
+       int ticks;
+       get_option (&str, &ticks);
+       cache_decay_ticks = ticks;
+       return 1;
+}
+
+__setup("decay=", decay);
+
+/*
+ * # of ticks an idle task is considered cache-hot.  Highly application-dependent.  There
+ * are apps out there which are known to suffer significantly with values >= 4.
+ */
+unsigned long cache_decay_ticks = 10;  /* equal to MIN_TIMESLICE */
 
 static void
 smp_tune_scheduling (void)
 {
-       cache_decay_ticks = 10; /* XXX base this on PAL info and cache-bandwidth estimate */
-
        printk(KERN_INFO "task migration cache decay timeout: %ld msecs.\n",
               (cache_decay_ticks + 1) * 1000 / HZ);
 }