* jidong xiao <[email protected]> wrote:
> Hi, Ingo,
>
> I am looking the source code of function softlockup_tick()
>
> 137 /* Warn about unreasonable delays: */
> 138 if (now <= (touch_timestamp + softlockup_thresh))
> 139 return;
> 140
> 141 per_cpu(print_timestamp, this_cpu) = touch_timestamp;
> 142
> 143 spin_lock(&print_lock);
> 144 printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for
> %lus! [%s:%d]\n",
> 145 this_cpu, now - touch_timestamp,
> 146 current->comm, task_pid_nr(current));
> 147 print_modules();
> 148 print_irqtrace_events(current);
> 149 if (regs)
> 150 show_regs(regs);
> 151 else
> 152 dump_stack();
> 153 spin_unlock(&print_lock);
> 154
> 155 if (softlockup_panic)
> 156 panic("softlockup: hung tasks");
>
> my kernel is kdb patched kernel, and it looks like if I stay in kdb
> for more than 60 seconds, I will receive a warning about softlockup
> when I leave kdb. it is very annoying to see the warning message
> especially in SMP environment, sometimes this could even hung the
> machine. A simple way here is:
>
> #ifdef CONFIG_KDB
> not trigger softlockup or set softlockup_thresh to be a very high value.
> #elseif
> trigger softlockup if CPU stuck for more than 60 seconds
> #endif
>
> However I feel this approach is far from perfect. Do you have any
> advice on how to avoid this warning?
Where does kdb spend this time? It's probably polling on something
(keyboard ports?) - so the right approach would be to fix up the
touch_timestamp or so.
I suspect kgdb has similar problems - if you fix it there and if you
have to touch kernel/softlockup.c for that i can apply those bits
even though kdb patches are not upstream.
Ingo
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