ipv4: save cpu cycles from check_leaf()
Erase memory pages as soon as they are freed to prevent new processes getting old information
zalloc tweak
init: apply SCHED_FIFO to kthreadd

Hotplug (cpu_up) latency currently suffers because the system
must wait for kthreadd to spawn certain kthreads (such as the
migration and workqueue kthreads) and for them to run for
the first time. Setting SCHED_FIFO will cause kthreadd to run
immediately. The newly created kthreads will inherit the scheduler
policy and run immediately also.

The scheduling policy of newly created kthreads is already set
back to SCHED_NORMAL in kthread_create_on_node, so nothing needs
to be done to restore normal scheduling behavior for the kthreads
once spawned.

Change-Id: I236ceb29845cf58ea1ea886fc3210ccaab2dd792
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
reduce sleep duration in wait_task_inactive
Min readahead 16 -> 32