Processor is running in the highest frequency with schedutil - TT Scheduler

[alitajelsir]

• I tried linux-tt 5.15.3-4 and linux-cacule 5.15.5-2 from AUR in Arch Linux, and in both the processor is running in the highest frequency with schedutil in intel_pstate=passive
• The same happens with powersave and performance in intel_pstate=active
• I'm using tlp to set the governor
• This doesn't happen with ondemand
• Strangely enough, if I change from schedutil to ondemand and back to schedutil, the scaling will work as expected, but it revert to the highest frequency after reboot.
• If it helps, this doesn't happen with linux zen 5.15.4.zen1-1
• Any information I can provide to help?
• Thanks in advance!

[ptr1337]

• I tried linux-tt 5.15.3-4 and linux-cacule 5.15.5-2 from AUR in Arch Linux, and in both the processor is running in the highest frequency with schedutil in intel_pstate=passive

  • The same happens with powersave and performance in intel_pstate=active

  • I'm using tlp to set the governor

  • This doesn't happen with ondemand

  • Strangely enough, if I change from schedutil to ondemand and back to schedutil, the scaling will work as expected, but it revert to the highest frequency after reboot.

  • If it helps, this doesn't happen with linux zen 5.15.4.zen1-1

  • Any information I can provide to help?

  • Thanks in advance!

How about if you using as cmdline intel_pstate=hwp ? Could be also a problem form the tt-scheduler.

Check if the cmdline and call back please.

[alitajelsir]

• In linux-tt and linux-cacule:
  • With intel_pstate=hwp or intel_pstate=active and powersave or performance the processor is running at the highest frequency without turbo (1.8 GHz in i5-8250U)
  • With intel_pstate=passive highest frequency with turbo (3.4 GHz)
• In linux-zen:
• With intel_pstate=passive (400 MHz)

[ptr1337]

Its a issue from the scheduler when no_hz_full is used i think.

See here:

https://github.com/hamadmarri/TT-CPU-Scheduler/issues/5

@hamadmarri

[ptr1337]

• In linux-tt and linux-cacule:

  • With intel_pstate=hwp or intel_pstate=active and powersave or performance the processor is running at the highest frequency without turbo (1.8 GHz in i5-8250U)
  • With intel_pstate=passive highest frequency with turbo (3.4 GHz)

  • In linux-zen:

  • With intel_pstate=passive (400 MHz)

You can also try 'intel_pstate=enable'. If its not getting solved, we need to switch to tickless idle only mode instead of completly tickless.

[alitajelsir]

• Tried linux-tt 5.15.6-1 but with the same result.

• Changing to ondemand and back to schedutil fixes the locked frequency. So I'm doing this abomination:

  [Unit]
  Description=Set ondemend governor then schedutil
  After=multi-user.target
  
  [Service]
  Type=oneshot
  ExecStart=/usr/bin/sh -c 'sleep 5 && cpupower frequency-set -g ondemand && cpupower frequency-set -g schedutil'
  
  [Install]
  WantedBy=multi-user.target

[ptr1337]

That’s a known issue at the tt kernel. Maybe it’s gonna fixed soon.

I thought first it’s the no_hz_full and changed this back to the old default

Same with the preempt behavior. But if there are no changes for you, it can be changed back.

Maybe do a issue at the tt scheduler repo.