On Sat, 8 Aug 2015 19:10:17 -0400
Paul Gortmaker [off-list ref] wrote:

So we took 20 IRQs in 5s, or 4/s ; not quite the 1/s minimum, but definitely not
the HZ/s we'd get w/o NOHZ_FULL.  Re-running it got consistently 18-20 IRQ / 5s.

OK, so NO_HZ_FULL still isn't great on -rt, but this shows that it
keeps disturbances much lower than without it.

Thanks for the report!

-- Steve

I specifically did NOT unplug and replug cores to "clean" them of tasks; the
hotplug code just seems to unstable for that from what I've seen in the past,
and by the looks of the irq counts above, there was no need to either.

The rootfs was basically a ubu 14.10 server install (no X11/gfx) -- not that
it should matter - so long as other tasks weren't running on the nohz cores.

Paul.
--

quoted

Enjoy,

-- Steve