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Thread: Intel Releases Linux Thermal Daemon

  1. #11
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    Quote Originally Posted by wargames View Post
    Quick question: why don't they just patch the current cpufreq subsystem ? Why reinvent the wheel ?

    Last question: that daemon runs in user space ? How efficient is that ? do we really a daemon for something that can be done by the kernel ?
    Why run it in kernel, if it can be run in userland? That's how all the power daemons worked so far (laptop-mode-tools, cpupower, fancontrol etc.), and the cpufreq kernel governors are just there to do one thing and one thing only - change the CPU frequency depending on the load. They don't detect temperatures and all that.

  2. #12
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    Quote Originally Posted by wargames View Post
    Quick question: why don't they just patch the current cpufreq subsystem ? Why reinvent the wheel ?

    Last question: that daemon runs in user space ? How efficient is that ? do we really a daemon for something that can be done by the kernel ?
    The Cpufreq subsystem handles controlling the CPU, via the governors which is CPU agnostic.. There's a reason the only options are: OnDemand, Performance, Powersave, and Conservative (and Userspace, but ive never seen that one get used o.O). This is about putting a watchdog daemon in place that says "I only ever want the internal temperature of the computer to get THIS hot." Lets call it 80degreess Celsius. If it ever hits 81 degrees or higher, then the daemon starts limiting the frequency of the CPU (and probably the GPU for intel's case) to keep things at the specified temperature. If we keep Cpufreq CPU agnostic-- as it should be-- it would probably way over-complicate things as far as abstracting away the differences in Intel vs AMD CPU's and drivers.

    The upside to this, and not using just the cpufreq subsystem is we can use both. We can tell cpufreq "Use the ondemand governor." and then tell the Daemon "80 degrees max." So until the CPU starts hitting the high temps, you're getting the full performance of the CPU. And the daemon will only kick in if needed.

    As far as why isn't it kernel space... I'm guessing the temperature reading is likely being handled by lm_sensors and then the daemon just continually checks the output of 'sensors', if that was done in kernel there'd be no way to guarantee lm_sensors existence, also everytime it'd go to check the temperature, wouldn't there be a context switch from kernel to userspace and back to kernel?

  3. #13
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    Quote Originally Posted by Ericg View Post
    There's a reason the only options are: OnDemand, Performance, Powersave, and Conservative (and Userspace, but ive never seen that one get used o.O).
    It gets used all the time... from userland. It's just not set by default, because you need to have a userland daemon that would implement its own governor for it, and it's not available early during boot. One such a daemon is launched, it can manually set the governor to "userspace".

  4. #14
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    Quote Originally Posted by GreatEmerald View Post
    It gets used all the time... from userland. It's just not set by default, because you need to have a userland daemon that would implement its own governor for it, and it's not available early during boot. One such a daemon is launched, it can manually set the governor to "userspace".
    What i meant was i've never seen a program actually use the Userland daemon, nor have I ever seen it recommended, nor have I ever seen it being used by default on any distro. I'm sure there is SOME program out there (such as Launched) that uses it, ive just never seen it.

  5. #15
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    I like it. fancontrol never worked well and is an ugly hack.

    What I've always missed is freely defined filters for fan voltage/PWM. I want to take temperature sensors 1...N, run them each through a digital filter to compensate for the low pass response of the thermal mass and then combine them with realtime data like P states to arrive at the fan control output (and probably high pass filter that to compensate for the fan inertia.)

  6. #16
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    Selling Hardware that don't gives the power that's described in the advertising sounds like a fraud to me.
    And thermal control should be done outside of a maybe crashed OS.

    What happens to your warranty if your device gets damaged because of a crashed OS ? Is your warranty
    void because you are using a non certified OS with a given patch level and non certified applications ?

  7. #17
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    Quote Originally Posted by dibal View Post
    Selling Hardware that don't gives the power that's described in the advertising sounds like a fraud to me.
    And thermal control should be done outside of a maybe crashed OS.

    What happens to your warranty if your device gets damaged because of a crashed OS ? Is your warranty
    void because you are using a non certified OS with a given patch level and non certified applications ?
    what the hell are you talking about?

  8. #18
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    Quote Originally Posted by Ericg View Post
    what the hell are you talking about?
    Devices that need help from the OS to not being physical destroyed are crap.

  9. #19
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    Quote Originally Posted by dibal View Post
    Devices that need help from the OS to not being physical destroyed are crap.
    And that's why they don't?.. If your parts are ventilated correctly, then you won't need anything else. These daemons are there to decrease the noise while still keeping the hardware cool enough.

  10. #20
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    Quote Originally Posted by dibal View Post
    Devices that need help from the OS to not being physical destroyed are crap.
    This isn't about not being destroyed Dibal, this is about restricting thermal output. Such as on a phone or Tablet where you don't have fans and probably have a very small heatsink the CPU would probably be fine with the heat, its more so Bout the person holding it. Or in mg case its about the Linux kernel and Intel oss driver not having as good power management as windows 7 and therefore I have to watch for overheats. this daemon would help take that risk away for me.

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