Re: [RFC PATCH] clocksource: increase watchdog retries

From: Paul E. McKenney
Date: Thu Oct 28 2021 - 14:42:15 EST


On Thu, Oct 28, 2021 at 06:20:25PM +0200, Jiri Wiesner wrote:
> On Wed, Oct 27, 2021 at 02:38:29PM -0700, Paul E. McKenney wrote:
> > I had something like this pending, but people came up with other workloads
> > that resulted in repeated delays. In those cases, it does not make sense
> > to ever mark the affected clocksource unstable. This led me to the patch
> > shown below, which splats after about 100 consecutive long-delay retries,
> > but which avoids marking the clocksource unstable. This is queued on -rcu.
> >
> > Does this work for you?
> >
> > commit 9ec2a03bbf4bee3d9fbc02a402dee36efafc5a2d
> > Author: Paul E. McKenney <paulmck@xxxxxxxxxx>
> > Date: Thu May 27 11:03:28 2021 -0700
> >
> > clocksource: Forgive repeated long-latency watchdog clocksource reads
>
> Yes, it does. I have done 100 reboots of the testing machine (running
> 5.15-rc5 with the above patch applied) and TSC was stable every time. I
> am going to start a longer test of 300 reboots for good measure and
> report back next week. J.

Very good, and thank you for giving it a go! If it passes the upcoming
tests, may I have your Tested-by?

Thanx, Paul