Re: [PATCH] sched/nohz: add debugfs control over sched_tick_max_deferment

From: Kevin Hilman
Date: Mon Sep 29 2014 - 11:11:32 EST

Frederic Weisbecker <fweisbec@xxxxxxxxx> writes:

> On Fri, Sep 26, 2014 at 12:45:32PM -0700, Kevin Hilman wrote:
>> From: Kevin Hilman <khilman@xxxxxxxxxx>
>> Allow debugfs override of sched_tick_max_deferment in order to ease
>> finding/fixing the remaining issues with full nohz.
>> The value to be written is in jiffies, and -1 means the max deferment
>> is disabled (scheduler_tick_max_deferment() returns KTIME_MAX.)
>> Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
>> Signed-off-by: Kevin Hilman <khilman@xxxxxxxxxx>
> So, I'm worried that it becomes a hack that everybody uses to shutdown
> the tick completely then nobody will come and fix the issue that prevents
> from doing it properly.


> I seriously doubt this will be used for development purpose to help
> fixing the real problem.

Well, that's what I was using it for, until I was distracted by other

> Quite the opposite. If developers want to do
> testing, they can as well comment out the call to scheduler_max_tick_deferment().

OK, fair enough.


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