/srv/irclogs.ubuntu.com/2021/04/15/#ubuntu-kernel.txt

=== halvors1 is now known as halvors
=== mIk3_09 is now known as mIk3_08
WimpressI've run into an issue with the schedutil governor on Threadripper using Hirsute.15:14
WimpressSchedutil is default for Zen CPUs now.15:14
WimpressI run 4x NVME Gen4 AIC in RAID 0. 15:15
WimpressThe system will hard lock when high I/O15:16
WimpressWhen I backup the Gen4 AIC RAID 0 array to a NVME Gen 3 RAID 0 array, the throughput reach 1 GigaBYTE per second.15:18
WimpressIf schedutil is the elected governor, the system will hard lock. I can reproduce this 2 out of 3 backups.15:19
WimpressI have since made OnDemand the default governor and stability is restored. 15:19
WimpressAnyone seen similar reports?15:20
kwilczynskiWimpress: Hi. I am not sure how you report issues to Ubuntu's Kernel team, but this might also warrant a Kernel Bugzilla report, if you can be asked. :)15:24
Wimpresskwilczynski: Yes, I think so. I thought I'd go hunting for someone else to confirm what I seeing first :)15:31
kwilczynski:)15:31
WimpressI have a couple of people I can collab with on the testing.15:31
kwilczynskiI wish I could help you.15:31
kwilczynskiBut I will be able to afford Threadripper sometime before retirement :)15:32
WimpressWho have similar 3970X systems and AICs15:32
kwilczynskiAsk Linus :D15:32
WimpressWell, indeed. I see his workstation is a good candidate for testing this :D15:32
kwilczynskiIf you open Bugzilla, then posting on LKML might... might... not get you lunched if you include the Bugzilla link.15:33
kwilczynskilynched*15:33
WimpressThanks for the advice.15:33
WimpressNoted.15:33
kwilczynskiIn all seriousness. It's an expensive kit, so not a lot of folks would have it.15:33
kwilczynskiWhich is why I recommended Bugzilla, as often kernel hackers lurk there and they might have similar machine.15:34
kwilczynskiPlus then it's easier to post to LKML asking.15:34
WimpressI know some enthusiasts with appropriate kit and one of them is tweaker who will enjoy digging into this.15:34
kwilczynskiNice!15:34
kwilczynskiYeah, if they can help, and have similar kit, then it would be ace.15:34
WimpressI have tried to rule out common issues, so disable PBO and XMP. Tried two BIOS revisions.15:35
kwilczynskiOne thing to keep in mind.15:36
kwilczynskiDid you try latest stable?15:36
WimpressStable what? Kernel?15:36
kwilczynskiIf you have 5.4 or 4.5 or something... the first thing people will do is to ask you to run latest.15:36
kwilczynskiYeah.15:36
kwilczynskiThe is a chance... some chance, that this was an issue that was already addressed15:36
WimpressYes. I was running 20.04 until 2 days ago.15:36
kwilczynski20.04 is which one?15:36
kwilczynski5.10?15:37
WimpressSo, was running a 5.4 kernel.15:37
kwilczynskiAhh, well.15:37
kwilczynskiThat's hardly recent.15:37
WimpressWhich doesn't have schedutil15:37
kwilczynskiIf you know how, try building 5.1215:37
WimpressI can test that.15:37
kwilczynskiIf that also has issues, then also if you know how (easy to learn how) you could try to bisect changes across the kernel releases to see which one might cause it. But this would be a lot of work.15:38
WimpressWell, my bisect would be pretty coarse right now, schedutil bad, ondemand good ;)15:41
WimpressBut I can see if schedutil was reliable at some point in it's introduction.15:41
kwilczynski:)15:41
kwilczynskiThat does help, indeed. :)15:42
kwilczynskiWimpress: If you spent time doing this, I'd be grateful to you a lot, for helping others, etc. :)15:42
WimpressI will test it. I also have some other AMD/Ryzen hardware and Gen4 NVME. So, I'll also see if this is reproducible on not exotic hardware.15:43
kwilczynskiAce!15:46
kwilczynskiIf you need someone running 7+ years old hardware, do reach out :P15:46

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