On Wed, 13 May 2015 10:12:36 +0200
Sebastian Andrzej Siewior [off-list ref] wrote:

* Steven Rostedt | 2015-05-11 20:15:06 [-0400]:

quoted

I'm backporting this to the stable releases, and I'm a bit worried
about the above comment. The new Scheduler IPI code uses work queues and
requires it to be done in a hard irq.

The IPI part is only done for the high-prio which is only used by NOHZ.
Everyone else gets in via softiq as we did it before.

My push/pull RT tasks via IPI, uses the irq_work to do this. It has
nothing to do with NOHZ, and will cause serious latencies if it is done
by softirq.

-- Steve