Re: [PATCH v13 00/12] support "task_isolation" mode

[Chris Metcalf]

On 7/21/2016 10:20 PM, Christoph Lameter wrote:
> On Thu, 21 Jul 2016, Chris Metcalf wrote:
> > On 7/20/2016 10:04 PM, Christoph Lameter wrote:
> > unstable, and then scheduling work to safely remove that timer.
> > I haven't looked at this code before (in kernel/time/clocksource.c
> > under CONFIG_CLOCKSOURCE_WATCHDOG) since the timers on
> > arm64 and tile aren't unstable.  Is it possible to boot your machine
> > with a stable clocksource?
> It already as a stable clocksource. Sorry but that was one of the criteria
> for the server when we ordered them. Could this be clock adjustments?

We probably need to get clock folks to jump in on this thread!

Maybe it's disabling some built-in unstable clock just as part of
falling back to using the better, stable clock that you also have?
So maybe there's a way of just disabling that clocksource from the
get-go instead of having it be marked unstable later.

If you run the test again after this storm of unstable marking, does
it all happen again?  Or is it a persistent state in the kernel?
If so, maybe you can just arrange to get to that state before starting
your application's task-isolation code.

Or, if you think it's clock adjustments, perhaps running your test with
ntpd disabled would make it work better?

--
Chris Metcalf, Mellanox Technologies
http://www.mellanox.com