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Thread: Is CPU scaling not working in 15?

  1. #1

    Default Is CPU scaling not working in 15?

    Back when I had 42.3, the lscpu command would show lower frequencies (about 800MHz) when the system was not doing anything (idle).
    Now with 15.0, it always shows 1696 MHz (which is the max speed of this celeron processor).

    I have installed tlp and setting lower max frequencies in /etc/default/tlp doesn't seem to have any effect (1696 MHz, no matter what settings i select).

    The command watch -n.1 "cat /proc/cpuinfo | grep \"^[c]pu MHz\"" shows 1696 MHz for as long as I keep it running. The system is idle CPU load is 0 to 1 percent, yet it looks like it's running on max speed.

    With watch -n.1 "cat /proc/cpuinfo | grep \"^[c]pu MHz\"" running, i pull out the power adapter, the system switches to battery power, everything idle, but both cores are running at 1696MHz even when on battery.

    Is this really what's going on? Or is this just some bug that's misreporting the current speed?
    Is there a way to fix this?

    Thanks..

  2. #2
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    Default Re: Is CPU scaling not working in 15?

    Hi
    Use cpupower command;
    Code:
    cpupower frequency-info
    What driver is in use?
    Cheers Malcolm °¿° SUSE Knowledge Partner (Linux Counter #276890)
    SUSE SLE, openSUSE Leap/Tumbleweed (x86_64) | GNOME DE
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  3. #3

    Default Re: Is CPU scaling not working in 15?

    Quote Originally Posted by malcolmlewis View Post
    Hi
    Use cpupower command;
    Code:
    cpupower frequency-info
    What driver is in use?
    Hello Malcolm,
    Thanks for your reply,
    Output of cpupower frequency-info while plugged in:

    Code:
    analyzing CPU 0:
      driver: intel_pstate
      CPUs which run at the same hardware frequency: Not Available
      CPUs which need to have their frequency coordinated by software: Not Available
      maximum transition latency:  Cannot determine or is not supported.
      hardware limits: 500 MHz - 1.60 GHz
      available cpufreq governors: performance
      current policy: frequency should be within 500 MHz and 1.60 GHz.
                      The governor "powersave" may decide which speed to use
                      within this range.
      current CPU frequency: Unable to call hardware
      current CPU frequency: 1.59 GHz (asserted by call to kernel)
      boost state support:
        Supported: no
        Active: no
    Output of cpupower frequency-info while on battery:

    Code:
    analyzing CPU 0:
      driver: intel_pstate
      CPUs which run at the same hardware frequency: Not Available
      CPUs which need to have their frequency coordinated by software: Not Available
      maximum transition latency:  Cannot determine or is not supported.
      hardware limits: 500 MHz - 1.60 GHz
      available cpufreq governors: performance
      current policy: frequency should be within 500 MHz and 800 MHz.
                      The governor "powersave" may decide which speed to use
                      within this range.
      current CPU frequency: Unable to call hardware
      current CPU frequency: 798 MHz (asserted by call to kernel)
      boost state support:
        Supported: no
        Active: no
    Output of lscpu (both on battery and plugged-in):

    Code:
    Architecture:        x86_64
    CPU op-mode(s):      32-bit, 64-bit
    Byte Order:          Little Endian
    CPU(s):              2
    On-line CPU(s) list: 0,1
    Thread(s) per core:  1
    Core(s) per socket:  2
    Socket(s):           1
    NUMA node(s):        1
    Vendor ID:           GenuineIntel
    CPU family:          6
    Model:               61
    Model name:          Intel(R) Celeron(R) CPU 3215U @ 1.70GHz
    Stepping:            4
    CPU MHz:             1696.056
    CPU max MHz:         1600.0000
    CPU min MHz:         500.0000
    BogoMIPS:            3392.11
    Virtualization:      VT-x
    L1d cache:           32K
    L1i cache:           32K
    L2 cache:            256K
    L3 cache:            2048K
    NUMA node0 CPU(s):   0,1
    Flags:               fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 sdbg cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer xsave rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb invpcid_single pti tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust erms invpcid rdseed intel_pt xsaveopt ibpb ibrs stibp dtherm arat pln pts
    cpupower frequency-info does show frequency reduction when AC is removed. Does this mean it's working okay? There are a few "Not available" entries in cpupower frequency-info, are these expected? Why is lscpu and cpupower frequency-info not in agreement?

  4. #4
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    Default Re: Is CPU scaling not working in 15?

    Hi
    Run it as root user to see all the info. You might want to have a read here;
    https://www.kernel.org/doc/html/v4.1...el_pstate.html

    Some folks disable it to fall back to the acpi version which will allow more frequency shifting.
    Cheers Malcolm °¿° SUSE Knowledge Partner (Linux Counter #276890)
    SUSE SLE, openSUSE Leap/Tumbleweed (x86_64) | GNOME DE
    If you find this post helpful and are logged into the web interface,
    please show your appreciation and click on the star below... Thanks!

  5. #5

    Default Re: Is CPU scaling not working in 15?

    As long as it's working, I figure there's no point poking around..
    Thanks for the link, m reading it now, very interesting

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