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Samsung Introduces "LAB" Linux Frequency Governor

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  • Samsung Introduces "LAB" Linux Frequency Governor

    Phoronix: Samsung Introduces "LAB" Linux Frequency Governor

    Samsung developers last week provided patches for a new cpufreq governor dubbed "LAB", or the "Legacy Application Boost", for the Linux kernel...

    http://www.phoronix.com/vr.php?view=MTM0NzI

  • #2
    That won't work!

    That won't work out as the Samsung engineers expected.
    It is a common misconception the powersave governor actually runs more efficient than ondemand.
    The opposite is true: Running at a lower clockrate increases the time until the CPU can jump back into Idle state, which in turn increases the load-time and energy consumption.

    So, when the Samsung engineers want to lower the frequency in case mutliple cores are under heavy load, the frequency would effectively be lowered when the system is under heavy, parallelized load
    , effectively increasing the load time.

    This is not effective.

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    • #3
      It reduces the heat output tremendously.

      Have you ever tried to run Linux on a notebook using a full AMD stack (AMD processor + AMD graphics cards + AMD northbridge) without forcing the powersave govenor to be active at all times? You can literally soften a pencil eraser enough to remould it after putting it behind the notebook's vents.

      I speak from personal experience.
      Last edited by Sonadow; 04-10-2013, 01:05 AM.

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      • #4
        Originally posted by Sonadow View Post
        It reduces the heat output tremendously.

        Have you ever tried to run Linux on a notebook using a full AMD stack (AMD processor + AMD graphics cards + AMD northbridge) without forcing the powersave govenor to be active at all times? You can literally soften a pencil eraser enough to remould it after putting it behind the notebook's vents.

        I speak from personal experience.
        My observations as well. Anything other than the powersave governor makes my HTPC fry itself once it tries to do more or less anything that is remotely demanding (due to fairly low air flow capability). With powersave, it never reaches dangerous temperatures. This is also with an AMD (Phenom II) processor.

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        • #5
          Less heat, but more energy consumption

          Originally posted by GreatEmerald View Post
          My observations as well. Anything other than the powersave governor makes my HTPC fry itself once it tries to do more or less anything that is remotely demanding (due to fairly low air flow capability). With powersave, it never reaches dangerous temperatures. This is also with an AMD (Phenom II) processor.
          The computer runs with less Watts over a longer period of time. In effect, it runs cooler, but computation needs more energy overall.
          Just tell me if you want me to give you an example.

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          • #6
            Originally posted by frign View Post
            The computer runs with less Watts over a longer period of time. In effect, it runs cooler, but computation needs more energy overall.
            Thankfully, an HTPC never really needs to do anything extraordinarily complex with computations.

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            • #7
              Originally posted by frign View Post
              The computer runs with less Watts over a longer period of time. In effect, it runs cooler, but computation needs more energy overall.
              Just tell me if you want me to give you an example.
              We're aware that it uses more frign, but for some bizarre reason linux seems to be worse at thermal management than windows (I dont know how thats possible... im just speaking from experience.)

              For example. This very laptop (Dell XPS 13z) running Arch linux, if I place it on my lap in such a way that my leg blocks the vent the laptop will gradually rise in temperature until it hits 95C and then BIOS kills the power to the entire laptop to prevent damage.

              The same laptop running Windows 7 doing the same thing, also with my leg blocking the vent, will hit 85C and stay there, never shutting down.

              ^While anecdotal evidence, this isnt a "This happened once, so im telling the story." I had Arch Linux on this laptop for about 8 months or so and would accidentally overheat it at least once a week. I've had Win7 on this thing for about a month now and havent accidentally overheated it even once.

              If I ever put arch linux back on this laptop I very well may stick to the powersave governor just to make sure I dont accidentally damage the internals from thermal output

              Comment


              • #8
                Originally posted by Ericg View Post
                We're aware that it uses more frign, but for some bizarre reason linux seems to be worse at thermal management than windows (I dont know how thats possible... im just speaking from experience.)
                It's open knowledge that Linux is inferior to Windows where thermal management is concerned. Generally, as long as one is using the open drivers heat is always going to be an issue.

                Once again, it's personal experience, but running my AMD notebook off the open drivers always had the graphics card and the processor idling at a very high 62 - 65 C, even with the powersave governor activated since 2009 till today. Compiling software or running Netbeans can see the temps climb to near critical levels of 80+ C and the notebook subsequently kills itself to protect the internals. This never happened under Windows.

                When Catalyst was installed back then the temps can drop to as low as 57 - 59C. Unfortunately, my card is no longer supported by Catalyst so my laptop today doubles up as both a notebook and a crotch warmer / hand warmer.

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                • #9
                  Sadly a common problem

                  Originally posted by Ericg View Post
                  We're aware that it uses more frign, but for some bizarre reason linux seems to be worse at thermal management than windows (I dont know how thats possible... im just speaking from experience.)

                  For example. This very laptop (Dell XPS 13z) running Arch linux, if I place it on my lap in such a way that my leg blocks the vent the laptop will gradually rise in temperature until it hits 95C and then BIOS kills the power to the entire laptop to prevent damage.

                  The same laptop running Windows 7 doing the same thing, also with my leg blocking the vent, will hit 85C and stay there, never shutting down.

                  ^While anecdotal evidence, this isnt a "This happened once, so im telling the story." I had Arch Linux on this laptop for about 8 months or so and would accidentally overheat it at least once a week. I've had Win7 on this thing for about a month now and havent accidentally overheated it even once.

                  If I ever put arch linux back on this laptop I very well may stick to the powersave governor just to make sure I dont accidentally damage the internals from thermal output
                  Ok, good to know that. Most applets show up the "powersave" governor and most normal users think it actually saves power.

                  Laptops are an unique case when it comes to Linux: I for example have a small Apple Desktop computer and actually had to write my own fan-control software, because the Kernel was just doing such a bad job with it.
                  I would recommend everybody to do the same to keep the temperature low enough. But still, my computer idles at 42C, which is a lot for my purposes.

                  Comment


                  • #10
                    Originally posted by frign View Post
                    Laptops are an unique case when it comes to Linux: I for example have a small Apple Desktop computer and actually had to write my own fan-control software, because the Kernel was just doing such a bad job with it.
                    I would recommend everybody to do the same to keep the temperature low enough. But still, my computer idles at 42C, which is a lot for my purposes.
                    Well of course I'm running lm_sensors with fancontrol. It's still not all that helpful, though. The fact that the sensor data of the HTPC CPU is blacklisted from lm_sensors isn't helping, either (although there are motherboard CPU sensors - just that they can't track each core and are not as close to the CPU).

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                    • #11
                      Originally posted by Ericg View Post
                      We're aware that it uses more frign, but for some bizarre reason linux seems to be worse at thermal management than windows (I dont know how thats possible... im just speaking from experience.)

                      For example. This very laptop (Dell XPS 13z) running Arch linux, if I place it on my lap in such a way that my leg blocks the vent the laptop will gradually rise in temperature until it hits 95C and then BIOS kills the power to the entire laptop to prevent damage.

                      The same laptop running Windows 7 doing the same thing, also with my leg blocking the vent, will hit 85C and stay there, never shutting down.

                      ^While anecdotal evidence, this isnt a "This happened once, so im telling the story." I had Arch Linux on this laptop for about 8 months or so and would accidentally overheat it at least once a week. I've had Win7 on this thing for about a month now and havent accidentally overheated it even once.

                      If I ever put arch linux back on this laptop I very well may stick to the powersave governor just to make sure I dont accidentally damage the internals from thermal output
                      Same for me, but we are not alone https://bbs.archlinux.org/viewtopic.php?id=149901

                      my post:
                      same for my Laptop. The temps on archlinux are significantly higher than on Windows. For me thats around 10C difference, too.
                      I didnt compare it to ubuntu, but I shall do that. Also I will compare the temps of my desktop PC soon (Arch vs Ubuntu vs Windows 7).
                      I started a similar thread in the German forums some 2 months ago: https://bbs.archlinux.de/viewtopic.php?id=22089

                      Arch in general seems to be very affected as there is a vast numberof complains about cpu overheating in the forums
                      e.g. https://bbs.archlinux.org/viewtopic.php?id=143580
                      https://bbs.archlinux.org/viewtopic.php?id=148456
                      https://bbs.archlinux.org/viewtopic.php?id=148695

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                      • #12
                        For people with an AMD gpu: the oss drivers keep the gpu in the "mid" or even "high" profile, even if it's not doing anything. That's because a (really) small number of gpus tend to output errors/artifacts on the "low" profile. However, this increases temperature. If you want to enable dynamic power profile or force a particular profile (you may want to, expecially on laptops), follow this steps from archwiki.

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                        • #13
                          Originally posted by cip91 View Post
                          For people with an AMD gpu: the oss drivers keep the gpu in the "mid" or even "high" profile, even if it's not doing anything. That's because a (really) small number of gpus tend to output errors/artifacts on the "low" profile. However, this increases temperature. If you want to enable dynamic power profile or force a particular profile (you may want to, expecially on laptops), follow this steps from archwiki.
                          Thank you, I'll look through it!

                          Comment


                          • #14
                            Originally posted by Nuc!eoN View Post
                            Thank you, I'll look through it!
                            Dynpm only alternates between mid and high profiles. Also it doesn't always complete the reclock during the v-blank so sometimes when it switches you see brief flickering on the screen. We're still waiting on AMD to release proper PM docs to figure out why our reclocking takes longer then a v-blank to complete and why catalyst doesn't.

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                            • #15
                              Myself, I use "low" profile, conservative governor (believe it or not, it actually does make a difference in temperature), and phc (with a patch for 3.8...)
                              Besides that, I've got thinkpad_acpi configured to allow fan control--I use "level auto" by default, but thinkfan or a script to switch to level 7 for high loads.

                              I rather wish there were a daemon that combines the features of acpid, thinkfan, and cpufreqd, so you can base settings on cpu frequency, programs running, acpi events, _and_ temperatures.

                              Oh, and by the way...LAB is more-or-less like Turbo Boost, except for its relation to the nominal frequency and capabilities of the processor.

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