Rescheduling Interrupts

What are Rescheduling Interrupts?

With multi core machines, such as Intel Centrino Duos, the scheduler tries to spread processor activity across as many cores as possible. The general rule of thumb is that it is preferable to have as many processes running on all the cores in lower power (lower clock frequencies) rather than have one core really busy running at full speed while other cores are sleeping.

When the scheduler decides to offload work from one core to another sleeping core, a kernel IPI "message" is sent to a sleeping core to wake it up from a low power sleep to make it start running a process. These IPI events are reported by powertop as "Rescheduling Interrupts". The information is available by reading /proc/interrupts - the IPI events are reported as an interrupt.

Generally speaking wakeup events are caused by timer wakeups or interrupts from hardware and these causes processes to be woken up and get scheduled to run. The scheduler will generate IPIs when it deems it necessary to put these woken up processed onto a sleeping core, hence a system with lots of wakeups or interrupts may manifest many "Rescheduling Interrupts". 

If powertop is reporting many hundreds or possibly thousands of "Rescheduling Interrupts" then there probably is a problem with a BIOS setting (misconfigured interrupt setup) or a misbehaving application (generating lots of wakeup from timer in threads).

https://help.ubuntu.com/community/ReschedulingInterrupts