title: Generate Backtraces of Threads Waiting for IO Operations
name: sleepingBeauties.stp
version: 1.0
author: anonymous
keywords: io scheduler backtrace
subsystem: scheduler
status: proposed
exit: user-controlled
output: trace
scope: system-wide
description: The script monitors the time that threads spend in waiting for IO operations (in "D" state) in the wait_for_completion function.  If a thread spends over 10ms, its name and backtrace is printed, and later so is the total delay.
test_check: stap -p4 sleepingBeauties.stp
test_installcheck: stap sleepingBeauties.stp -c "sleep 0.2"