Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.debian.kernel > #79416

Bug#1038981: capping maximum frequency no longer works in kernel 6.1

Cross-posted to 2 groups.

Show all headers | View raw

[Multipart message — attachments visible in raw view] - view raw

Package: linux-image-6.1.0-9-amd64
Version: 6.1.27-1
Below, I try to cap the frequency for each of my processor cores, but some cores resists:
# for i in `seq 0 7`; do echo "400000"> /sys/devices/system/cpu/cpu$i/cpufreq/scaling_max_freq && cat /sys/devices/system/cpu/cpu$i/cpufreq/scaling_cur_freq; done 400002 400004 399989 2300000 2300000 2300000 400013 399519
Moreover, the cores that resist changes each time; e.g., the next run yields this:
# for i in `seq 0 7`; do echo "400000"> /sys/devices/system/cpu/cpu$i/cpufreq/scaling_max_freq && cat /sys/devices/system/cpu/cpu$i/cpufreq/scaling_cur_freq; done 400024 2300000 400002 400020 2300000 400000 399930 400008
I tried to read the frequency via /proc/cpuinfo:
# for i in `seq 0 7`; do echo "400000"> /sys/devices/system/cpu/cpu$i/cpufreq/scaling_max_freq; done && cat /proc/cpuinfo | grep MHz cpu MHz : 400.001 cpu MHz : 399.989 cpu MHz : 2300.000 cpu MHz : 400.107 cpu MHz : 1028.210 cpu MHz : 399.942 cpu MHz : 400.001 cpu MHz : 400.004
I also tried to use tlp (yes, I said TLP_DEFAULT_MODE=BAT, TLP_PERSISTENT_DEFAULT=1, CPU_BOOST_ON_BAT=0, and CPU_HWP_DYN_BOOST_ON_BAT=0) and sysfs packages; all methods yield the similar results: capping the frequency of all cores doesn't work. I tried to cap all at, say, 800 MHz, 1.2 GHz, and 2 GHz instead, but the result is often (but not always!) the same: a few cores often (but not always!) resist and run at higher frequencies up to 2.4 GHz. Only seldom I see the expected:
# for i in `seq 0 7`; do echo "400000"> /sys/devices/system/cpu/cpu$i/cpufreq/scaling_max_freq; done && cat /proc/cpuinfo | grep MHz cpu MHz : 400.004 cpu MHz : 399.988 cpu MHz : 399.999 cpu MHz : 400.011 cpu MHz : 399.980 cpu MHz : 400.048 cpu MHz : 400.002 cpu MHz : 400.008
But running cat /proc/cpuinfo | grep MHz a few seconds later yields again a few lines with 2300.000.
The governor is powersave everywhere.
For kernel 5 with Debian 11 (which I can no longer test), everything worked like a charm (or at least I always observed all-400-MHz back then). So either the new kernel is erroneous or my processor broke somehow (perhaps, during the upgrade). It has Intel(R) Core(TM) i7-10610U CPU @ 1.80GHz.
Who is the culprit? What to do?
Gratefully,
AlMa

Back to linux.debian.kernel | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

Bug#1038981: capping maximum frequency no longer works in kernel 6.1 "Al Ma" <alma0@ro.ru> - 2023-06-24 00:30 +0200
  Bug#1038981: Acknowledgement (capping maximum frequency no longer works in kernel 6.1) AlMa <AlMa0@ro.ru> - 2023-06-24 01:00 +0200
  Bug#1038981: scaling_cur_freq ≰ scaling_max_freq "Al Ma" <alma0@ro.ru> - 2023-07-20 01:30 +0200
  Bug#1038981: capping maximum frequency no longer works in kernel 6.1 Diederik de Haas <didi.debian@cknow.org> - 2023-08-01 00:20 +0200
    Bug#1038981: capping maximum frequency no longer works in kernel 6.1 AlMa <AlMa0@ro.ru> - 2023-08-01 01:50 +0200
      Bug#1038981: capping maximum frequency no longer works in kernel 6.1 Diederik de Haas <didi.debian@cknow.org> - 2023-08-01 10:50 +0200
        Bug#1038981: capping maximum frequency no longer works in kernel 6.1 AlMa <AlMa0@ro.ru> - 2023-08-01 16:50 +0200

csiph-web