On Fri, Aug 17, 2012 at 09:40:39AM -0400, Theodore Ts'o wrote:

On Fri, Aug 17, 2012 at 02:09:15PM +0800, Fengguang Wu wrote:

quoted

Ted,

I find ext4 write performance dropped by 3.3% on average in the
3.6-rc1 merge window. xfs and btrfs are fine.

Two machines are tested. The performance regression happens in the
lkp-nex04 machine, which is equipped with 12 SSD drives. lkp-st02 does
not see regression, which is equipped with HDD drives. I'll continue
to repeat the tests and report variations.

Hmm... I've checked out the commits in "git log v3.5..v3.6-rc1 --
fs/ext4 fs/jbd2" and I don't see anything that I would expect would
cause that.  The are the lock elimination changes for Direct I/O
overwrites, but that shouldn't matter for your tests which are
measuring buffered writes, correct?

Is there any chance you could do me a favor and do a git bisect
restricted to commits involving fs/ext4 and fs/jbd2?

No problem :)

Thanks,
Fengguang