Android has added a scheduler trace point which shows why a thread was blocked called  sched_blocked_reason which can be very useful for determining why a process is blocked in the kernel

here's an example

sched_blocked_reason: pid=1984 iowait=1 caller=__wait_on_buffer+0x40/0x43


I'd like to take this information and attach it to the cpu slices when a thread is shown as in uninterruptible sleep.