I know that this is controversial, for further background please see the
discussion in http://bugzilla.kernel.org/show_bug.cgi?id=10761
Facts:
- Bugzilla statistics
(not counting duplicate bugs and bugs closed as INVALID):
- 6 CPU scheduler regressions reported during 2.6.25-rc
1 of them still open as of 2.6.26-rc4
- 6 CPU scheduler regressions reported during 2.6.26-rc until now
5 of them still open as of 2.6.26-rc4
- at about half of the CPU scheduler regressions are related to
group scheduling
- Peter Zijlstra said in Bugzilla bug #10761:
> Adrian Bunk said:
> The CPU scheduler is currently regressing horribly often, and half of the
> regressions are in group scheduling.
That is because group scheduling is horribly complex and was never
feature complete - trying to solve that is high on my list of
priorities.
My opinion:
- features that alter existing kernel functionality should (different
from drivers for previously not supported hardware) be in a very good
state before being offered in stable kernels
- Peter is wrong when he thinks that EXPERIMENTAL would somehow hide
known-problematic features - in practice nearly everyone has to have
EXPERIMENTAL enabled (e.g. for some hardware driver)
- group scheduling already has a history of people accidentally enabling
it and then running into problems
I therefore suggest this patch to let GROUP_SCHED depend on BROKEN.
Once it is feature complete and then got the usual testing through
-next I'll have no objections against offering it again to users.
Signed-off-by: Adrian Bunk <bunk@kernel.org>
---
c67cfbbb40895b72760865527dd1949631b1d183 diff --git a/init/Kconfig b/init/Kconfig
index d9526b5..564deba 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -333,7 +333,7 @@ config HAVE_UNSTABLE_SCHED_CLOCK
config GROUP_SCHED
bool "Group CPU scheduler"
- depends on EXPERIMENTAL
+ depends on BROKEN
default n
help
This feature lets CPU scheduler recognize task groups and control CPU
--
