[PATCH 0/3] kmod: Make nohz-full friendly + cleanups

From: Frederic Weisbecker
Date: Mon Jul 06 2015 - 11:34:00 EST


Usermodehelpers kernel threads are nohz-full unfriendly because they
force some explicit CPU-wide affinity that happen to disturb user code
that don't want to see noise on isolated CPUs.

So I spent many time on that, despite the one-liner end result.
The out-of-date comments didn't help much, especially it wasn't clear
why we need khelper at all, probably it was first introduced to bring
necessary asynchronous code but I couldn't justify that with the current
code.

I wrote patches to remove it but finally realized we still need it to
inherit a system wide (or nohz-full housekeeping) CPU affinity on
usermodehelper kernel threads because some usermodehelper callers may
have a reduced affinity (eg: per cpu workqueues). All I needed eventually
was to improve the comments to highlight that purpose. And remove a
nohz-full unfriendly wide affinity forcing.

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

HEAD: 9a0ad418b7739fbbe4add684551aa5582a58718b

Thanks,
Frederic
---

Frederic Weisbecker (3):
kmod: Bunch of internal functions renames
kmod: Add up-to-date explanations on the purpose of each asynchronous levels
kmod: Remove unecessary explicit wide CPU affinity setting


kernel/kmod.c | 61 +++++++++++++++++++++++++++++++++++++++++------------------
1 file changed, 43 insertions(+), 18 deletions(-)
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