On 05.06.2011 11:55, Ingo Molnar wrote:
* Arne Jansen<lists@xxxxxxxxxxxxxx> wrote:( Arne, please also double check on a working bootup that the NMI watchdog is actually ticking, by checking the NMI counts in /proc/interrupts go up slowly but surely on all CPUs. )It does, but _very_ slowly. Some CPUs do not count up for tens of minutes if the machine is idle. If I generate some load like 'make tags', the counters go up quite quickly. After 4 minutes and one 'make cscope' it looks like this: NMI: 8 13 43 5 2 3 22 1 Non-maskable interrupts But I never see a single tick on console or in dmesg, even when I replace the early_printk with a printk.hm, that might be because the NMI watchdog uses halted cycles to tick. That's not a problem (the kernel cannot lock up while there are no cycles ticking) but nevertheless could you work this around please by starting 8 infinite shell loops: for ((i=0; i<8; i++)); do while : ; do : ; done& done ? This will saturate all cores and makes sure the NMI watchdog is ticking everywhere. Hopefully this wont make the bug go away :-)
OK, now we get going. I get the ticks, the bug is still there, and all CPUs still tick after the lockup. I also added an early_printk inside the lockup-if, and it reports hard lockups. At first for only one or 2 CPUs, and after some time all CPUs are locked up. -Arne -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
|