Re: SCHED_DEADLINE as user

On Thu, 23 Aug 2018 14:37:39 +0200
Juri Lelli [off-list ref] wrote:

On 23/08/18 12:43, luca abeni wrote:

quoted

On Thu, 23 Aug 2018 12:23:50 +0200
Juri Lelli [off-list ref] wrote:  

[...]

quoted

quoted

But then what is a sane inheritance mechanism?  

In my understanding (please correct me if I am wrong), this is an
orthogonal issue: if I understand well, the issue preventing
non-root usage of SCHED_DEADLINE is that a task inheriting a dl
entity is not throttled (when the current runtime rrives to 0, the
deadline is postponed, but the task stays schedulable). So, I think
that removing this behaviour should allow to use SCHED_DEADLINE
without starving other tasks...  

Right, potential starvation would be gone...

quoted

Then, there is the issue about the deadline and runtime to inherit.
And I agree that this is important (and the solution is not easy),
but you have this issue even if you use the current "dl_boosted"
behaviour... No?  

... but, while it's true that current inheritance has problems w/ o
w/o boosting behaviour, I wonder if the problem might be more painful
for a normal user that it's still under runtime enforcement.

I think that the only way to have an answer to this doubt is to try :)

Disabling
enforcement seems to hide a bit the fact that we need proper
inheritance. :-(

My impression is that it hides the problem in some situations, but
the Murphy law ensures that the issue will appear when the quality of
the audio is more important :)


			Luca