Re: [RFC PATCH 0/9] Introduce housekeeping subsystem

From: Chris Metcalf
Date: Fri Jul 21 2017 - 15:48:38 EST


On 7/21/2017 9:21 AM, Frederic Weisbecker wrote:
I'm leaving for two weeks so this is food for thoughts in the meantime :)

We have a design issue with nohz_full: it drives the isolation features
through the *housekeeping*() functions: kthreads, unpinned timers,
watchdog, ...

But things should work the other way around because the tick is just an
isolation feature among others.

So we need a housekeeping subsystem to drive all these isolation
features, including nohz full in a later iteration. For now this is a
basic draft. In the long run this subsystem should also drive the tick
offloading (remove residual 1Hz) and all unbound kthreads.

git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git
nohz/0hz

HEAD: 68e3af1de5db228bf6c2a5e721bce59a02cfc4e1

For the series:

Reviewed-by: Chris Metcalf <cmetcalf@xxxxxxxxxxxx>

I spotted a few typos that you should grep for and fix for your next version:
"watchog", "Lets/lets" instead of "Let's/let's", "overriden" (should have two d's).

The new housekeeping=MASK boot option seems like it might make it a little
irritating to specify nohz_full=MASK as well. I guess if setting NO_HZ_FULL_ALL
implied "all but housekeeping", it becomes a reasonably tidy solution. To make
this work right you might have to make the housekeeping option early_param
instead so its value is available early enough.

--
Chris Metcalf, Mellanox Technologies
http://www.mellanox.com