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Benchmarking The Intel P-State, CPUfreq Changes

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  • #11
    Originally posted by GreatEmerald View Post
    Or just make a systemd unit file that sets the kernel variables to needed values on each boot, if a static setting is desired.
    That works too, its just a personal preference for me to use the designated tool rather than hack together a unit file / shell script. But you are right, that would work

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    • #12
      Originally posted by Pontostroy View Post
      Problem with _RADEON_ driver and kernel 3.8+
      Is this with Intel or AMD cpu? Also, are you sure that it's a problem only with 3.8+? IIRC I observed reduced performance with ondemand governor long before 3.8, I'm used to run custom scripts to switch cpu governor and gpu profile between ondemand/low and performance/high depending on whether I need max performance (for games and benchmarks) or not.

      Probably we need more clever cpu governor that would take into account gpu activity to ensure best performance with OpenGL & OpenCL apps. Though I think the behavior of the ondemand governor can also be improved by tuning its parameters, e.g. the following seems to help on my system (though as I said I'm usually just switching to performance governor, so I didn't test it a lot):

      Code:
      echo 60 > /sys/devices/system/cpu/cpufreq/ondemand/up_threshold
      This parameter is cpu load (%) that triggers increase of cpu freq, default value is 95%, but according to "cpupower monitor" cpu load per core is simply not reaching this threshold with most opengl apps and r600g for me, due to load balancing between cores etc.

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      • #13
        Originally posted by Ericg View Post
        That works too, its just a personal preference for me to use the designated tool rather than hack together a unit file / shell script. But you are right, that would work
        Well, when using Arch or Gentoo, such unit files shouldn't be much of a problem. You're configuring everything manually, anyway.

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        • #14
          Originally posted by GreatEmerald View Post
          Well, when using Arch or Gentoo, such unit files shouldn't be much of a problem. You're configuring everything manually, anyway.
          True, but I also like being able to go back to the wikis and run off them. So if I start deviating from the wiki's too much then I might forget what I ever did originally haha

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          • #15
            Originally posted by vadimg View Post
            Though I think the behavior of the ondemand governor can also be improved by tuning its parameters, e.g. the following seems to help on my system (though as I said I'm usually just switching to performance governor, so I didn't test it a lot):

            Code:
            echo 60 > /sys/devices/system/cpu/cpufreq/ondemand/up_threshold
            This parameter is cpu load (%) that triggers increase of cpu freq, default value is 95%, but according to "cpupower monitor" cpu load per core is simply not reaching this threshold with most opengl apps and r600g for me, due to load balancing between cores etc.
            95% does seem too high, honestly. Perhaps they designed it with the expectation that most CPU heavy loads would be hitting 100%.

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            • #16
              don't select governors.,...

              Originally posted by AnonymousCoward View Post
              95% does seem too high, honestly. Perhaps they designed it with the expectation that most CPU heavy loads would be hitting 100%.
              The native P state driver does NOT use cpufreq governors.... no point selecting or setting them (in fact, nothing good can come out that so please just don't do that)

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              • #17
                Originally posted by fenrus View Post
                The native P state driver does NOT use cpufreq governors.... no point selecting or setting them (in fact, nothing good can come out that so please just don't do that)
                also one general note: for benchmarks that run fully flat out, don't expect many changes; that's the easiest case where pretty much every governor will pick the highest performance point and stay there.
                the most interesting benchmarks for this sort of thing are cases where the cpu is not 100% busy.

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                • #18
                  Wow!!! LMFAO! Somebody doesn't know the first thing about frequency governors or how to test them. Unless there is something particularly broken about them, when maximum CPU is demanded, they will ALL ramp the CPU up to full power. PERIOD. END OF STORY. That means that there WILL BE no difference in peak performance, which means that testing the peak performance of them is entirely absurd!

                  What you need to test is POWER CONSUMPTION and SYSTEM RESPONSIVENESS at low to moderate loads.

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                  • #19
                    Originally posted by droidhacker View Post
                    Wow!!! LMFAO! Somebody doesn't know the first thing about frequency governors or how to test them. Unless there is something particularly broken about them, when maximum CPU is demanded, they will ALL ramp the CPU up to full power. PERIOD. END OF STORY. That means that there WILL BE no difference in peak performance, which means that testing the peak performance of them is entirely absurd!

                    What you need to test is POWER CONSUMPTION and SYSTEM RESPONSIVENESS at low to moderate loads.
                    Not the powersave ones, and conservative can affect the non-peak performance.

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                    • #20
                      Powersavings ?

                      Hi,

                      The pstate is around now for several weeks and I wonder if there are people, who have actually measured some energy savings.

                      So, before I try my newest kernel compilation, are there any powertop measurements or similar which could show
                      improvements in battery life. This is what concerns me most, I am not interested in playing high-cpu games but to hear
                      experiences in normal programming/email/surfing usage.

                      Thanks to all the others

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