xfs: does mkfs.xfs require fancy switches to get decent performance? (was Tux3 Report: How fast can we fsync?)

[Mike Galbraith]

Here's something that _might_ interest xfs folks.

cd git (source repository of git itself)
make clean
echo 3 > /proc/sys/vm/drop_caches
time make -j8 test

ext4    2m20.721s
xfs     6m41.887s <-- ick
btrfs   1m32.038s
tux3    1m30.262s

Testing by Aunt Tilly: mkfs, no fancy switches, mount the thing, test.

Are defaults for mkfs.xfs such that nobody sane uses them, or does xfs
really hate whatever git selftests are doing this much?

	-Mike