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>
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File | Mode | Size |
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.gitignore | -rw-r--r-- | 151 bytes |
Kconfig | -rw-r--r-- | 5.3 KB |
Makefile | -rw-r--r-- | 2.3 KB |
gen_init_cpio.c | -rw-r--r-- | 13.1 KB |
initramfs_data.S | -rw-r--r-- | 1.3 KB |
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