Re: [Xen-devel] [PATCH] x86/watchdog: Use real timestamps for watchdog timeout

[Tim Deegan <tim@xxxxxxx>]

At 21:32 +0100 on 23 May (1369344726), Andrew Cooper wrote:
> Do not assume that we will only receive interrupts at a rate of nmi_hz.  On a
> test system being debugged, I observed a PCI SERR being continuously asserted
> without the SERR bit being set.  The result was Xen "exceeding" a 300 second
> timeout within 1 second.

Sounds like the CPU is indeed stuck, and the watchdog has just optimized
away the 5 minutes of back-to-back NMIs. :)

Handling this case it nice, but I wonder whether this patch ought to
detect and report ludicrous NMI rates rather than silently ignoring
them.  I guess that's hard to do in an NMI handler, other than by
adjusting the printk when we crash.

Tim.

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