On Wed, 2007-05-09 at 19:42 +0530, Anant Nitya wrote:
> Hi,
> Ever since I upgrade to 2.6.21/.1, system log is filled with following 
> messages if I enable CONFIG_NO_HZ=y, going through archives it seems ingo 
> sometime back posted some patch and now it is upstream, but its not helping 
> here. If I disable NOHZ by kernel command line nohz=off this problem 
> disappears. This system is P4/2.40GHz/HT with SMP/SMT on in kernel config. 
> One more thing that I noticed is this problem only arises while using X or 
> network otherwise plain command line with no network access don't trigger 
> this with nohz=on.

Is this independent of the load on the system ? i.e. : What happens if
you only use the console and run a kernel compile with -j4 ?

> [EMAIL PROTECTED] [~]$ >>  grep NOHZ /var/log/messages
> May  8 03:38:14 rudra kernel: [  419.271195] NOHZ: local_softirq_pending 02
> May  8 03:38:14 rudra kernel: [  419.271663] NOHZ: local_softirq_pending 02

The patch below ratelimits the printk output, so your syslog is not
flooded anymore.

        tglx

Index: linux-2.6.21/kernel/time/tick-sched.c
===================================================================
--- linux-2.6.21.orig/kernel/time/tick-sched.c
+++ linux-2.6.21/kernel/time/tick-sched.c
@@ -167,9 +167,15 @@ void tick_nohz_stop_sched_tick(void)
                goto end;
 
        cpu = smp_processor_id();
-       if (unlikely(local_softirq_pending()))
-               printk(KERN_ERR "NOHZ: local_softirq_pending %02x\n",
-                      local_softirq_pending());
+       if (unlikely(local_softirq_pending())) {
+               static int ratelimit;
+
+               if (ratelimit < 10) {
+                       printk(KERN_ERR "NOHZ: local_softirq_pending %02x\n",
+                              local_softirq_pending());
+                       ratelimit++;
+               }
+       }
 
        now = ktime_get();
        /*


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