A-Team_Digital_Solutions/android_kernel_motorola_sm6375
Watch
2
0
Fork
You've already forked android_kernel_motorola_sm6375
 0
mirror of https://github.com/BobTheBlinker/android_kernel_motorola_sm6375.git synced 2026-10-24 13:44:26 -04:00
Code Issues Projects Releases Packages Wiki Activity

Revert "sched: Improve scalability via 'CPU buddies', which withstand random perturbations"

Browse source 
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>
This commit is contained in:
Linus Torvalds 2012-09-16 12:29:43 -07:00
commit 37407ea7f9
3 changed files with 22 additions and 46 deletions
Download patch file Download diff file Expand all files Collapse all files

1
include/linux/sched.h
View file

@ -954,7 +954,6 @@ struct sched_domain {
unsigned int smt_gain;
int flags; /* See SD_* */
int level;
int idle_buddy; /* cpu assigned to select_idle_sibling() */
/* Runtime fields. */
unsigned long last_balance; /* init to jiffies. units in jiffies */