Comment # 43 on bug 1169774 from Jan Kara

Thanks for all the tests! This looks like a very different from the one
originally reported in this bug. The original issue was specific to ext4
filesystem while what you report now seems like a general slow down (just
affecting different filesystems to different extent - see how XFS build on
goat19 takes over 600s with TW kernel on XFS while it takes just 189s with 15.1
kernel on ext4 - it would be good to get comparison with 15.1 build on XFS but
I'd expect it to be close to ext4 numbers on that kernel). So I'll clone this
bug so that we don't confuse this bug.