Revision 37407ea7f93864c2cfc03edf8f37872ec539ea2b authored by Linus Torvalds on 16 September 2012, 19:29:43 UTC, committed by Linus Torvalds on 16 September 2012, 19:29:43 UTC
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>
1 parent 3f0c3c8
.gitignore
#
# NOTE! Don't add files that are generated in specific
# subdirectories here. Add them in the ".gitignore" file
# in that subdirectory instead.
#
# NOTE! Please use 'git ls-files -i --exclude-standard'
# command after changing this file, to see if there are
# any tracked files which get ignored after the change.
#
# Normal rules
#
.*
*.o
*.o.*
*.a
*.s
*.ko
*.so
*.so.dbg
*.mod.c
*.i
*.lst
*.symtypes
*.order
modules.builtin
*.elf
*.bin
*.gz
*.bz2
*.lzma
*.xz
*.lzo
*.patch
*.gcno
#
# Top-level generic files
#
/tags
/TAGS
/linux
/vmlinux
/vmlinuz
/System.map
/Module.markers
/Module.symvers
#
# Debian directory (make deb-pkg)
#
/debian/
#
# git files that we don't want to ignore even it they are dot-files
#
!.gitignore
!.mailmap
#
# Generated include files
#
include/config
include/linux/version.h
include/generated
arch/*/include/generated
# stgit generated dirs
patches-*
# quilt's files
patches
series
# cscope files
cscope.*
ncscope.*
# gnu global files
GPATH
GRTAGS
GSYMS
GTAGS
*.orig
*~
\#*#
Computing file changes ...
