[SOLVED] Unhappy with CPU frequency / performance

[regox]

I have a laptop with a fairly recent CPU, an i7-10610U. It has 8 Cores and a maximum frequency of 4.9 GHz.

What I don't understand is why my CPU frequency (and therefore noticeably performance) is dropping as soon as I perform computationally heavy tasks. In Idle, the CPU is around 800 MHz - 1 GHz. During normal browsing, PDF viewing etc. it jumps up to and beyond 4 GHz, so far so good.

But when I'm compiling a kernel or use QEMU/KVM, the frequency is stuck at 400 MHz (or sub-1GHz most of the time) and my system feels very sluggish to use. In my understanding, the CPU should be at its maximum frequency in those cases. The frequency should only go down when the task is finished or thermal throttling kicks in. I don't think it's a thermal problem, the CPU reports 52 °C (125° F) right now, that should be okay.

I am using "performance" governor

[mike155]

1. Please post the output of
   

   Code:

   uname -a

   
   and of
   

   Code:

   cpupower frequency-info

   
   
   
2. Please run
   

   Code:

   while [ 1 ]; do i=1; done &

   
   That will run a job with a constant load in the background. Use 'top' to verify that this job is running. What are CPU frequency and CPU temperature? Let this test run for at least two minutes. Do CPU frequency and temperature reach stable values? Or do they jump up and down?
   
   
3. Run the command 3 more times. Use 'top' to verify that 4 jobs are running. What are CPU frequency and CPU temperature? Let this test run for at least two minutes. Do CPU frequency and temperature reach stable values? Or do they jump up and down?
   
   
4. Run this command 4 more times. Use 'top' to verify that 8 jobs are running. What are CPU frequency and CPU temperature? Let this test run for at least two minutes. Do CPU frequency and temperature reach stable values? Or do they jump up and down?
   
   
5. Kill the jobs running in the background
   

   Code:

   jobs kill %1 kill %2 ...

   
   

[Hu]

52C seems rather high for an idle CPU, though that would be quite reasonable under load. What were the system circumstances when you observed the 52C? If the system was idle then, what temperature does it reach when you have it under full load? My system idles in the 34C-38C range. Under full load for an extended period, I have seen it go as high as 80C.

[regox]

Thank you both for the replies.

[mike155]

Thanks for the test results.

Something is totally wrong with either your kernel or with your notebook. Maybe both. If I had to guess I would say that sleep states don't work.

Please post your kernel config using wgepaste.

[grknight]

You should read /usr/src/linux/Documentation/admin-guide/pm/intel_pstate.rst on how the intel_pstate driver works and how the governor is ignored to some extent.

[regox]

Thanks for your quick reply.

[NeddySeagoon]

regox,

[figueroa]

Not the same CPU, but I get very good CPU responsiveness on my i7-2600 (SandyBridge at least 11 years old) with intel_pstate=active on the kernel commandline and the powersave governor. It took me a long time to wrap my mind around PSTATE.

sensors show 47, 38, 37, and 47 on the four cores, in a warm room, Thunderbird in the background and Firerfox with two tabs, a Youtube video running in the background. CPU frequency bouncing around on all threads, but in the viscinity of minimum MHz. I don't believe I get any overheating at full loads.
_________________
Andy Figueroa
hp pavilion hpe h8-1260t/2AB5; spinning rust x3
i7-2600 @ 3.40GHz; 16 gb; Radeon HD 7570
amd64/23.0/split-usr/desktop (stable), OpenRC, -systemd -pulseaudio -uefi

[regox]

[Goverp]

If you're running bleeding edge kernels, are you also doing anything with fan controls? My current desktop has all sorts of ways to screw up the cooling! Or maybe the fan is broken.
_________________
Greybeard

[pietinger]

The behavior of Intels P-State Performance for a DESKTOP is:
When your cores are idle it switches all cores to BOOST frequency (if CPU has a boost; if not then to maximum). If your cores are under pressure it switches BACK to MAXimum frequency. The minimum frequency is almost not really needed ! (Sometimes it goes below MAX and of course it is not allowed to go below MIN) (I dont know for a notebook; never tried).

Recommendation for a NOTEBOOK (with a newer CPU than Intels 4.Gen) is P-State Powersave. This governor uses of course also MINimum frequency You should use only this one and not ACPI ... BUT ... you should also configure your kernel for using a Notebook: LPSS and all other options needed for A / THIS special notebook model. e.g.

[mike155]

[regox]

Thanks for all the help. I really appreciate it.

[mike155]

I have a Dell Latitude 5289 notebook with an Intel 5-7200U CPU @ 2.50GHz. I use the Intel pstate driver and the governor "powersave".

Below are the results on my machine. '# jobs' is the number of while loops running in parallel:

[regox]

Okay, so I think I finally found the problem. Although it was better with the fixes you suggested, the behavior was not repeatable and sometimes my laptop would still fall back to this 400 MHz-state sometimes. Especially on battery, this occurred more often. I tried several things over several months, but nothing was really satisfactory.

After some more searching, also specifically for my laptop model (Lenovo Thinkpad P14s), I found that other people (even on Windows OS sometimes!) seem to have similar problems. What finally helped me was throttled[1]. Seems like the limiting factor was the package power limit, that explains why my CPU frequency would collapse randomly under heavy load on all cores (because it trips some power limit). Now it is very stable for prolonged periods of time, even under full load at 3-4GHz while also getting reasonably hot, but never exceeding 95°C. I am very happy now with performance. Hopefully it stays that way now.

There is even an Overlay available for Portage and support for OpenRC! [2]

[1] https://github.com/erpalma/throttled
[2] https://github.com/erpalma/throttled-overlay

[AstroFloyd]