Linus Torvalds 37407ea7f9 Revert "sched: Improve scalability via 'CPU buddies', which withstand random perturbations" ...

This reverts commit 970e178985cadbca660feb02f4d2ee3a09f7fdda.

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 970e178985ca ("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

sched: Clean up parameter passing of proc_sched_autogroup_set_nice()

2012-03-02 12:23:49 +01:00

auto_group.h

sched: Move all scheduler bits into kernel/sched/

2011-11-17 12:20:22 +01:00

clock.c

sched: Move all scheduler bits into kernel/sched/

2011-11-17 12:20:22 +01:00

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

sched: Move all scheduler bits into kernel/sched/

2011-11-17 12:20:22 +01:00

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

Makefile

init_task: Create generic init_task instance

2012-05-05 13:00:21 +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

Merge branch 'sched/core' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into cputime-tip

2011-12-19 19:23:15 +01:00

stop_task.c

sched: Fix migration thread runtime bogosity

2012-08-13 18:41:55 +02:00