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
..
Makefile	init_task: Create generic init_task instance	2012-05-05 13:00:21 +02:00
auto_group.c	sched: Clean up parameter passing of proc_sched_autogroup_set_nice()	2012-03-02 12:23:49 +01:00
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	sched/debug: Fix printing large integers on 32-bit platforms	2012-05-14 15:05:28 +02:00
fair.c	Revert "sched: Improve scalability via 'CPU buddies', which withstand random perturbations"	2012-09-16 12:29:43 -07:00
features.h	sched: Fix more load-balancing fallout	2012-04-26 12:54:52 +02:00
idle_task.c	sched/nohz: Rewrite and fix load-avg computation -- again	2012-07-05 20:58:13 +02:00
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	sched: Remove sched_switch	2012-01-27 13:28:53 +01:00
stats.h	…
stop_task.c	sched: Fix migration thread runtime bogosity	2012-08-13 18:41:55 +02:00