Revert "Optimize EXT4 filesystem"

This reverts commit 716c8b6c5856a8450d969158f588f1a90a20d404.
Revert "mm: tweak sysctl params thx cocafe"

This reverts commit 3571d77253e090bc262343c5acbe1c555e38525e.
Revert "Revert " sched: Prevent wakeup to enter critical section needlessly""

This reverts commit b4356d363949877662591ae8b0b0f82d325bbcd1.
Revert "Revert "xens_config: update""

This reverts commit 0ec34c881e25631de8d19bf88f1855c9fe49c8f5.
Revert "Revert "xens_config: disable SCHEDSTATS""

This reverts commit f165545754dfca0bf9b1e54ffad79b9999a8c9af.