posix-timers: Shorten posix_cpu_timers/<CPU> kernel thread names

Shorten the softirq kernel thread names because they always overflow the
limited comm length, appearing as "posix_cpu_timer" CPU# times.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
posix-timers: Avoid wakeups when no timers are active

Waking the thread even when no timers are scheduled is useless.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
sched-delay-put-task.patch

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
sched-limit-nr-migrate.patch

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
sched-mmdrop-delayed.patch

Needs thread context (pgd_lock) -> ifdeffed. workqueues wont work with
RT

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>