Joel Becker wrote:
> Folks,
> Attached is a module, hangcheck-timer. It is used to detect
> when the system goes out to lunch for a period of time, such as when a
> driver like qla2x00 udelays a bunch.
> The module sets a timer. When the timer goes off, it then uses
> the TSC (warning: portability needed) to determine how much real time
> has passed.
> On a normal system, the real elapsed time will be almost
> identical to the expected timer duration. However, if a device decided
> to udelay for 60 seconds (or some other circumstance), the module takes
> notice. If the margin of error passes a threshold, the machine is
> rebooted.
> The module is currently used in a cluster environment. After
> some time out to lunch, the rest of the cluster will have given up on a
> machine. If the machine suddenly comes back and assumes it is still
> "live", bad things can happen.
> We can also see use for this in a debugging sense, for kernel
> hangs as well as driver code. That's why I'm proposing it for general
> inclusion.
> Comments? Thoughts?
>
> Joel
>
> Building:
> The module should happily build against most 2.4 kernels. The
> usual module building compile line:
> gcc -I /scratch/jlbec/kernel/linux-2.4.20-rc2/include \
> -DMODULE -D__KERNEL__ -DLINUX -c -o hangcheck-timer.o \
> hangcheck-timer.c
>
> Running:
> Load the module with insmod. There are two options.
> "hangcheck_tick=<seconds>" specifies the timer timeout, and
> "hangcheck_margin=<seconds" specifies the margin of error.
>
> Joel
>
There is already an NMI watchdog that is better than what you propose,
because it will also catch cases where something gets stuck with
interrupts disabled.
-- Brian Gerst- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Sat Nov 23 2002 - 22:00:37 EST