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

From: Chris Metcalf
Date: Fri Jul 22 2016 - 10:24:28 EST

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