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AMD Posts New "AMD-PSTATE" CPUFreq Driver Leveraging CPPC For Better Perf-Per-Watt

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  • #51
    I hope this driver is as flexible as CPUFreq because the Intel one isn't (just two power profiles and both are misleading)...

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    • #52
      Originally posted by numacross View Post
      I provided an explanation why desktop parts have higher idle power usage
      as a matter of fact, amd chiplet cpus have higher performance per watt than intel non-chiplet ones
      Originally posted by numacross View Post
      - the Infinity Fabric is an "external" interconnect, and that still holds. No matter how well the CPU chiplets are made they still have to communicate with the IO die, and the distance is long in terms of IC design. That will take a lot of power.
      if it was on same chip, it wouldn't be significantly closer, you'll just get larger chip with all its downsided

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      • #53
        Originally posted by pal666 View Post
        as a matter of fact, amd chiplet cpus have higher performance per watt than intel non-chiplet ones
        That depends on the workload, take for example this:

        Pretty sure Intel wins in perf/power here

        (yes, I know that it's an edge case)

        Originally posted by pal666 View Post
        if it was on same chip, it wouldn't be significantly closer, you'll just get larger chip with all its downsided
        I'm sorry, I don't know what you mean.

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        • #54
          Originally posted by numacross View Post
          I'm sorry, I don't know what you mean.
          I think they're referring to the fact that electricity would still have to travel a decent distance on a monolithic die but would inherit all the downsides of a monolithic chip.

          If they didn't use chiplets then they would have needed to make a 248-ish sq/mm die for the consumer market and a 794-ish sq/mm die for the server and workstation market. I'm not even sure if that latter is really even possible but clearly both would have worse yields (insanely bad yields for the Epyc die), lower clock speeds, etc. Realistically it would be slightly smaller because the IFOP would be stripped out and the I/O portion would be on a 7nm process instead of a 14nm process but they would still be large dies. One of the reasons they did the I/O die on an older process was actually because the PHYs tend not to shrink well with newer processes anyway.

          Going monolithic but keeping the same physical layout would waste a lot of space because a single die can only be rectangular. They would have to redo the layout and location of the I/O area. They'd either have to stretch the I/O area out resulting in intra-IO-area communication using more power, require CCX to CXX communication to travel the length of the I/O area, or place one CCX further from the I/O area than the other. It's entirely possible that the non-square layout that chiplets allow actually more ideal for the architecture in terms of consistency and power-usage than if the were forced to make it rectangular.

          I don't know if that's exactly what they were getting at but that might have been along the lines of what they meant.
          Last edited by Myownfriend; 10 September 2021, 11:14 PM.

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          • #55
            Originally posted by avem View Post

            That's true however Zen 2/3 CPUs idle power consumption is simply horrible. My 5800X idles at ... ~21W. Hopefully AMD will address it sooner that later but I don't have much hope for Zen 3+ CPUs. Maybe in time for Zen4 AMD will finally be able to compete on this metric with the competition.

            Speaking of this news: it's truly great, albeit four years late. Maybe Valve can push AMD to release the documentation for Zen CPUs MSRs as well to enable proper and full monitoring which is simply cringe worthy at the moment.

            Here's what you can see in Windows:



            Here's what you get in Linux:
            Code:
            k10temp-pci-00c3
            Adapter: PCI adapter
            CPU Primary T Control: +34.6°C
            Tdie: +34.6°C
            Tccd1: +29.8°C
            Use Zenmonitor in Linux.

            This is what I get on linux.

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            • #56
              Originally posted by pete910 View Post
              Use Zenmonitor in Linux.
              Zenmonitor (zenpower, last commit Jun 15, 2020) is dead unfortunately and it adds just few inputs.

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              • #57
                Originally posted by birdie View Post

                Zenmonitor (zenpower, last commit Jun 15, 2020) is dead unfortunately and it adds just few inputs.
                Still provides far more than the k10 driver though.

                Lists power usage ect, Not much more required I would have thought.

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                • #58
                  Originally posted by pete910 View Post

                  Still provides far more than the k10 driver though.

                  Lists power usage ect, Not much more required I would have thought.
                  I'm using turbostat to get my Ryzen CPU power use.

                  Here's a fork with support for Zen 3 CPUs: https://github.com/Ta180m/zenpower3
                  Last edited by birdie; 11 September 2021, 01:26 PM.

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                  • #59
                    I'll stop after this post - I promise.

                    AMD Ryzen 9 5900HX with the performance governor, the discrete RTX 3060 (75W) GPU being switched on and having processes use it, running KDE Plasma on Wayland but with the system otherwise idle and with the screen off.

                    Power usage from the wall, with the battery neither charging nor discharging:



                    I'll now show myself out...
                    Last edited by reba; 11 September 2021, 05:10 PM.

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                    • #60
                      Originally posted by reba View Post
                      I'll stop after this post - I promise.

                      AMD Ryzen 9 5900HX with the performance governor, the discrete RTX 3060 (75W) GPU being switched on and having processes use it, running KDE Plasma on Wayland but with the system otherwise idle and with the screen off.

                      Power usage from the wall, with the battery neither charging nor discharging:

                      I'll now show myself out...
                      A very good result, don't stop.

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