RE: [PATCH V2] kernel/watchdog: fix spurious hard lockups

[Liang, Kan]

> 
> On Mon, 17 Jul 2017, Liang, Kan wrote:
> > There are three proposed patches so far.
> > Patch 1: The patch as above which speed up the hrtimer.
> > Patch 2: Thomas's first proposal.
> > https://patchwork.kernel.org/patch/9803033/
> > https://patchwork.kernel.org/patch/9805903/
> > Patch 3: my original proposal which increase the NMI watchdog timeout
> > by 3X https://patchwork.kernel.org/patch/9802053/
> >
> > According to our test, only patch 3 works well.
> > The other two patches will hang the system eventually.
> > For patch 1, the system hang after running our test case for ~1 hour.
> > For patch 2, the system hang in running the overnight test.
> > There is no error message shown when the system hang. So I don't know
> > the root cause yet.
> 
> That doesn't make sense. What's the exact test procedure?

I don't know the exact test procedure. The test case is from our customer.
I only know that the test case makes calls into the x11 libs.

> 
> > BTW: We set 1 to watchdog_thresh when we did the test.
> > It's believed that can speed up the failure.
> 
> Believe is not really a technical measure....
> 

1 is a valid value for watchdog_thresh.
It was set through the standard proc interface.
/proc/sys/kernel/watchdog_thresh
It should not impacts the final test result.

Thanks,
Kan