Thread (33 messages) 33 messages, 10 authors, 2016-11-09

Re: [PATCH] sched/rt: RT_RUNTIME_GREED sched feature

From: Christoph Lameter <hidden>
Date: 2016-11-07 19:30:41
Also in: lkml

On Mon, 7 Nov 2016, Steven Rostedt wrote:
On Mon, 7 Nov 2016 10:55:38 -0600 (CST)
Christoph Lameter [off-list ref] wrote:
quoted
On Mon, 7 Nov 2016, Daniel Bristot de Oliveira wrote:
quoted
With these two options set, the user will guarantee some runtime
for non-rt-tasks on all CPUs, while keeping real-time tasks running
as much as possible.
Excellent this would improve the situation with deadlocks as a result of
cgroup_locks not being released due to lack of workqueue processing.
?? What deadlocks do you see? I mean, can you show the situation that
throttling RT tasks will cause deadlock?

Sorry, but I'm just not seeing it.
SCHED_RR tasks alternately running on on cpu can cause endless deferral of
kworker threads. With the global effect of the OS processing reserved
it may be the case that the processor we are executing never gets any
time. And if that kworker threads role is releasing a mutex (like the
cgroup_lock) then deadlocks can result.
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