Not 100% sure the article doesn't cover this, but if you want a constant rate of wakeups over time (not a precise duration of each sleep call), it's important t

Not 100% sure the article doesn't cover this, but if you want a constant rate of wakeups over time (not a precise duration of each sleep call), it's important to schedule your next sleep 1 period after your most recent intended wakeup time (in absolute time), not 1 period after the call to the sleep function (in relative time), to ensure that the time spent after sleep() returns before you call sleep() again doesn't accumulate with every sleep iteration and cause you to fall behind in real time.