* Interference from CFS scheduler
@ 2017-09-13 1:53 Allen Martin
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From: Allen Martin @ 2017-09-13 1:53 UTC (permalink / raw)
To: linux-rt-users
I've been trying to eliminate sources of unpredictability in the
latency of interrupt response in my real-time application, and I'm
struggling a bit with the CFS scheduler. If a SCHED_OTHER task was
preempted the rt scheduler eventually calls put_prev_task() which
results in a rb tree insert in the CFS scheduler. So the latency of
my real-time task depends on the scheduling class of the task I'm
interrupting and how many SCHED_OTHER tasks are in the runqueue, which
seems like a priority inversion.
Are there any ways to mitigate this other than trying to minimize the
number of SCHED_OTHER tasks in the system? Ideally what I'd really
like is to defer the work in put_prev_task_fair() until there's no
real-time work to do.
-Allen
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