Linus Torvalds 37407ea7f9 Revert "sched: Improve scalability via 'CPU buddies', which withstand random perturbations" ... This reverts commit 970e178985. Nikolay Ulyanitsky reported thatthe 3.6-rc5 kernel has a 15-20% performance drop on PostgreSQL 9.2 on his machine (running "pgbench"). Borislav Petkov was able to reproduce this, and bisected it to this commit 970e178985 ("sched: Improve scalability via 'CPU buddies' ...") apparently because the new single-idle-buddy model simply doesn't find idle CPU's to reschedule on aggressively enough. Mike Galbraith suspects that it is likely due to the user-mode spinlocks in PostgreSQL not reacting well to preemption, but we don't really know the details - I'll just revert the commit for now. There are hopefully other approaches to improve scheduler scalability without it causing these kinds of downsides. Reported-by: Nikolay Ulyanitsky <lystor@gmail.com> Bisected-by: Borislav Petkov <bp@alien8.de> Acked-by: Mike Galbraith <efault@gmx.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2012-09-16 12:29:43 -07:00
..
auto_group.c
auto_group.h
clock.c
core.c	Revert "sched: Improve scalability via 'CPU buddies', which withstand random perturbations"	2012-09-16 12:29:43 -07:00
cpupri.c	sched: Fix minor code style issues	2012-07-26 11:47:00 +02:00
cpupri.h
debug.c
fair.c	Revert "sched: Improve scalability via 'CPU buddies', which withstand random perturbations"	2012-09-16 12:29:43 -07:00
features.h
idle_task.c	sched/nohz: Rewrite and fix load-avg computation -- again	2012-07-05 20:58:13 +02:00
Makefile
rt.c	sched: Unthrottle rt runqueues in __disable_runtime()	2012-09-04 14:30:30 +02:00
sched.h	sched: Unthrottle rt runqueues in __disable_runtime()	2012-09-04 14:30:30 +02:00
stats.c
stats.h
stop_task.c	sched: Fix migration thread runtime bogosity	2012-08-13 18:41:55 +02:00