Hi Jon,
On 04/03/25 15:32, Jon Hunter wrote:
> Hi Juri,
>
> On 04/03/2025 08:40, Juri Lelli wrote:
> > Hello!
> >
> > Jon reported [1] a suspend regression on a Tegra board configured to
> > boot with isolcpus and bisected it to commit 53916d5fd3c0
> > ("sched/deadline: Check bandwidth overflow earlier for hotplug").
> >
> > Root cause analysis pointed out that we are currently failing to
> > correctly clear and restore bandwidth accounting on root domains after
> > changes that initiate from partition_sched_domains(), as it is the case
> > for suspend operations on that board.
> >
> > The way we currently make sure that accounting properly follows root
> > domain changes is quite convoluted and was indeed missing some corner
> > cases. So, instead of adding yet more fragile operations, I thought we
> > could simplify things by always clearing and rebuilding bandwidth
> > information on all domains after an update is complete. Also, we should
> > be ignoring DEADLINE special tasks when doing so (e.g. sugov), since we
> > ignore them already for runtime enforcement and admission control
> > anyway.
> >
> > The following implements the approach by:
> >
> > - 01/05: filter out DEADLINE special tasks
> > - 02/05: preparatory wrappers to be able to grab sched_domains_mutex on
> > UP
> > - 03/05: generalize unique visiting of root domains so that we can
> > re-use the mechanism elsewhere
> > - 04/05: the bulk of the approach, clean and rebuild after changes
> > - 05/05: clean up a now redundant call
> >
> > Please test and review. The set is also available at
> >
> > git@xxxxxxxxxx:jlelli/linux.git upstream/deadline/domains-suspend
>
>
> I know that this is still under review, but I have tested on my side and it
> is working for me, so feel free to include my ...
>
> Tested-by: Jon Hunter <jonathanh@xxxxxxxxxx>
Great to hear this and thanks for the super quick turn around with
testing. I will be implementing the changes that Waiman (and possibly
others) is suggesting and post a new version soon.
Best,
Juri
