Re: [PATCH 2/2] nohz: make nohz_full imply isolcpus

From: Chris Metcalf
Date: Fri Apr 03 2015 - 15:21:22 EST

On 04/03/2015 02:08 PM, Mike Galbraith wrote:
On Fri, 2015-04-03 at 12:24 -0400, cmetcalf@xxxxxxxxxx wrote:
From: Chris Metcalf <cmetcalf@xxxxxxxxxx>

It's not clear that nohz_full is useful without isolcpus also
set, since otherwise the scheduler has to run periodically to
try to determine whether to steal work from other cores.

Signed-off-by: Chris Metcalf <cmetcalf@xxxxxxxxxx>
Ack! nohz_full= as currently defined makes zero sense when the cpu
set (which should be spelled cpuset) remains connected to the
scheduler. Perturbation of tasks to PREVENT cpu domination is what
the scheduler does for a living. Sprinkling microsecond savers all
over the kernel is pretty silly if you don't shut down the mother lode
of perturbation.

Sounds like a thumbs up for this patch, then? :-)

Chris Metcalf, EZChip Semiconductor

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