Re: [PATCH] NMI watchdog config option (was: Re: [PATCH] NMI lockup and AltSysRq-P dumping calltraces on _all_ cpus via NMI IPI)

[Kirill Korotaev <dev@sw.ru>]

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> Kirill Korotaev <dev@sw.ru> wrote:
> 
>>BTW, why NMI watchdog is disabled by default?
> 
> 
> There was a significantly large string of reports of dying PCs in the
> 2.4.early timeframe.  These machines would mysteriously lock up after
> considerable periods of time and the problem was cured by disabling the NMI
> watchdog.  Nobody was ever able to solve it, so we changed it to default to
> off.
Hmm, it is strange, since we used 2.4 kernels with watchdog for years 
(starting from 2.4.1)...

> So much has changed in there that we might have fixed it by accident, and I
> do recall a couple of fundamental and subtle NMI bugs being fixed.  So
> yeah, it might be worth enabling it by default again.  Care to send a patch
> which does that?
I attached the patch which turns NMI watchdog on by default on i386.

Signed-Off-By: Pavel Emelianov <xemul@sw.ru>

Kirill

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--- linux-2.6.12-rc4/arch/i386/kernel/nmi.c.nmiwd	2005-05-07 09:20:31.000000000 +0400
+++ linux-2.6.12-rc4/arch/i386/kernel/nmi.c	2005-05-17 13:47:38.000000000 +0400
@@ -34,7 +34,7 @@
 
 #include "mach_traps.h"
 
-unsigned int nmi_watchdog = NMI_NONE;
+unsigned int nmi_watchdog = NMI_IO_APIC;
 extern int unknown_nmi_panic;
 static unsigned int nmi_hz = HZ;
 static unsigned int nmi_perfctr_msr;	/* the MSR to reset in NMI handler */