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AMD P-State vs. ACPI CPUFreq Testing With Ryzen Laptops On Linux 5.17

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  • smitty3268
    replied
    Originally posted by Eumaios View Post

    Didn't several tests provide this? For example, several SELENIUM benchmarks tested "Score per watt" (next to the little blue triangle showing whether higher or lower is better).
    The problem is that the tests are still running benchmarks at full speed. Which is pretty much the easiest thing to optimize for - you just run the CPU at full power.

    pstate is useful for cases where you're not running at full speed - in other words, non-benchmark loads. Something like a game test with fps capped to 60fps would be better, where you want the CPU to downclock when it can in order to save power, but still run as fast as it needs to.

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  • Eumaios
    replied
    amd-pstate performance looks like a great compromise for laptops for general operation!

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  • Eumaios
    replied
    Originally posted by FireBurn View Post
    It would have been useful if all the tests had performance per watt results, simply saying pstates + schedutil wasn't as fast doesn't really give the full picture especially when the percentage difference isn't that much but could make a difference in how long the battery lasts
    Didn't several tests provide this? For example, several SELENIUM benchmarks tested "Score per watt" (next to the little blue triangle showing whether higher or lower is better).

    Leave a comment:


  • Myownfriend
    replied
    Originally posted by birdie View Post
    That explains a lot. Thank you!

    Originally posted by Linuxxx View Post
    And since you own a multi-CCX Ryzen 5950X:
    How is the energy consumption with the performance governor during idle times?

    Previously someone had reported rising temperatures with such a setup, which maybe could have something to do with increased Infinity Fabric activity.

    Ever observed anything similar?
    I never really use the performance governor so I wouldn't know. I only really use schedutil and powersave.

    Leave a comment:


  • kiffmet
    replied
    phoronix Could you maybe test amd-pstate in conjunction with Alfred Chen's ProjectC/PDS scheduler and compare the results to the ones you got here in this article? CFS' thread distribution may be suboptimal on Ryzen when it comes to allowing for higher boost clocks. PDS is said to improve performance especially in gaming, which is where you've seen the greatest deficits with CFS + amd-pstate.

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  • Mez'
    replied
    Can't say it makes a compelling case to finally reboot any of my Zen2+ computers for the first time in 2022 with a 5.17 kernel (to enable the p-state driver)
    Last edited by Mez'; 12 April 2022, 07:26 AM.

    Leave a comment:


  • Linuxxx
    replied
    Originally posted by birdie View Post

    Phoronix: AMD P-State vs. ACPI CPUFreq Testing With Ryzen Laptops On Linux 5.17 One of the most prominent features of Linux 5.17 for end-users was the introduction of the AMD P-State driver that is designed to deliver better energy efficiency than the generic ACPI CPUFreq frequency scaling driver relied on by AMD Ryzen




    If you like numbers than it does aside from https://bugzilla.kernel.org/show_bug.cgi?id=215729
    So, with amd-pstate in idle:

    Powersave and performance (!) governors ~ 20W.
    Conservative ~ 21W.
    Ondemand ~ 23.5W.
    Thanks for doing these tests, Artem, but could you also add schedutil to the above mix, just to get the complete picture?

    Thanks again!

    Leave a comment:


  • birdie
    replied
    Originally posted by Myownfriend View Post
    I frequently use the powersave profile on my desktop because it's fine for every day tasks but the one thing I never understood was by the lowest frequency that Linux reports for my 5950X is 2200Mhz but Windows will go down to 1700Mhz.
    Phoronix: AMD P-State vs. ACPI CPUFreq Testing With Ryzen Laptops On Linux 5.17 One of the most prominent features of Linux 5.17 for end-users was the introduction of the AMD P-State driver that is designed to deliver better energy efficiency than the generic ACPI CPUFreq frequency scaling driver relied on by AMD Ryzen


    Originally posted by Myownfriend View Post
    Overall, AMD's P-state driver is pretty disappointing but does it at least allow for lower minimum clock frequencies?
    If you like numbers than it does aside from https://bugzilla.kernel.org/show_bug.cgi?id=215729

    Leave a comment:


  • Linuxxx
    replied
    Originally posted by Myownfriend View Post
    I frequently use the powersave profile on my desktop because it's fine for every day tasks but the one thing I never understood was by the lowest frequency that Linux reports for my 5950X is 2200Mhz but Windows will go down to 1700Mhz. Overall, AMD's P-state driver is pretty disappointing but does it at least allow for lower minimum clock frequencies?
    ACPI-cpufreq only reports three frequencies, but your AMD CPU will still enter C-states (sleep-states), which are the real power-savers, not lower frequencies.

    And since you own a multi-CCX Ryzen 5950X:
    How is the energy consumption with the performance governor during idle times?

    Previously someone had reported rising temperatures with such a setup, which maybe could have something to do with increased Infinity Fabric activity.

    Ever observed anything similar?

    Leave a comment:


  • Myownfriend
    replied
    I frequently use the powersave profile on my desktop because it's fine for every day tasks but the one thing I never understood was by the lowest frequency that Linux reports for my 5950X is 2200Mhz but Windows will go down to 1700Mhz. Overall, AMD's P-state driver is pretty disappointing but does it at least allow for lower minimum clock frequencies?

    Leave a comment:

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