Messages in this thread | | | Date | Fri, 19 Aug 2022 10:28:44 -0400 | Subject | Re: [RFC} Commit 8a99b6833c88 Moves Important Real-time Settings To DebugFS | From | Joseph Salisbury <> |
| |
On 8/18/22 21:38, Joseph Salisbury wrote: > > > On 8/18/22 16:31, Peter Zijlstra wrote: >> On Thu, Aug 18, 2022 at 03:53:28PM -0400, Joseph Salisbury wrote: >>> Hello, >>> >>> Some Ubuntu users are using the tuned package with a 5.15.x based >>> real-time >>> kernel. Tuned adjusts various sysctl options based on a specified >>> profile. >>> This userspace package has stopped working > 5.13 due to the following >>> commit: >>> >>> 8a99b6833c88 "(sched: Move SCHED_DEBUG sysctl to debugfs)" >>> >>> This commit moved some important real-time sysctl knobs to debugfs in >>> 5.13-rc1. It also appears some of the sysctl options were not moved, >>> sched_min_granularity_ns, for example. >>> >>> I was hoping to get some feedback on how to approach this. Would >>> upstream >>> real-time consider accepting a patch to the 5.15 real-time patch set >>> that >>> reverts this commit? Or a new patch that adds the sysctl settings >>> back? >>> Any other ideas or feedback would be appreciated! >> None of those knobs were available when SCHED_DEBUG=n, so relying on >> them is your error to begin with. > We have had SCHED_DEBUG=y while this kernel is in beta, so you are > correct. I need to investigate a different approach. >> >> Secondly, real-time? Which if those values affects anything in >> SCHED_FIFO/RR/DEADLINE ? > I am in the process of understanding how tuned[0] works. Many users > have reported success using tuned. One use case for tuned is to > assign isolated cores to real-time processes and then move managed > IRQs out of these isolated cores. This can be done easily with tuned > (I will research if there are other options to suggest). However, > tuned is trying to set the affected values when enabling a profile, > such as the real-time profile (Tuned offers many profiles based on a > workload type). > > I will investigate further to answer your point of what in > SCHED_FIFO/RR/DEADLINE those values affect. It could be those values > are not needed at all. The dependency on them might be left over from > some need that no longer exists. > > Thank you again for the feedback! > > [0] https://tuned-project.org/ > I also see that the github repo[0] is at version 2.19-rc1, and the version being testing is 2.15. Many of the issues we see may already be resolved.
I will find out how I can participate in the tuned community. At a minimum, I can start with testing and bug fixes.
Thanks again for your feedback, Peter. And sorry for the noise.
Thanks,
Joe
[0] https://github.com/redhat-performance/tuned
| |