The CONFIG_IPI_OPTIMIZE configuration option allows for the flagging
and subsequent signaling of IPIs to be optimized.
It does this by making each bit in the kernel's pending_ipi field
a flag that indicates whether the corresponding CPU might need an IPI
to trigger the scheduling of a new thread on that CPU.
When a new thread is made ready, we compare that thread against each
of the threads currently executing on the other CPUs. If there is a
chance that that thread should preempt the thread on the other CPU
then we flag that an IPI is needed for that CPU. That is, a clear bit
indicates that the CPU absolutely will not need to reschedule, while a
set bit indicates that the target CPU must make that determination for
itself.
Signed-off-by: Peter Mitsis <peter.mitsis@intel.com>
