If a task is performance-critical, pick_idle_cpu() checks if the
previous core is a big core or not. If not, don't try to run on previous
core since a performance-critical task is better to run on a big core.

Signed-off-by: Changwoo Min <[email protected]>

Signed-off-by: Changwoo Min <[email protected]>

An old BPF verifier does not allow calling bpf_cpumask_set_cpu() in the
BPF syscall context, so we defer actual bpf_cpumask_set_cpu() to the
timer handler, update_sys_stat(), to workaround the problem.

Signed-off-by: Changwoo Min <[email protected]>