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Hi all, I am in the process of thinking whether to use Linux on my Samsung notebook. Problem is that the Laptop comes with a cute feature called "Samsung Silent ...
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  1. #1
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    How to correctly throttle an AMG


    Hi all,

    I am in the process of thinking whether to use Linux on my Samsung notebook. Problem is that the Laptop comes with a cute feature called "Samsung Silent Mode", which throttles the CPU down to 800MHz and hence, all fans can go off, with an SDD the computer is absolutely silent. This works like a charme in Win7, but with Linux, I can't throttle it down to less than 1400MHz and having the fans blow like a Tomcat.

    My processor:

    linuxmint cpufreq # cat /proc/cpuinfo
    processor : 0
    vendor_id : AuthenticAMD
    cpu family : 21
    model : 16
    model name : AMD A6-4400M APU with Radeon(tm) HD
    Graphics stepping : 1
    microcode : 0x6001119 cpu
    MHz : 1400.000
    so while Win7 has no problem in throttling, cpufreq says it can't go with less than 1400:

    linuxmint cpufreq # cpufreq-info
    Treiber: acpi-cpufreq
    Hardwarebedingte Grenzen der Taktfrequenz: 1.40 GHz - 2.70 GHz
    mögliche Taktfrequenzen: 2.70 GHz, 2.40 GHz, 2.00 GHz, 1.70 GHz, 1.40 GHz
    mögliche Regler: conservative, ondemand, userspace, powersave, performance momentane Taktik: die Frequenz soll innerhalb 1.40 GHz und 2.70 GHz. liegen. momentane Taktfrequenz ist 2.70 GHz (verifiziert durch Nachfrage bei der Hardware). Statistik:2.70 GHz:6,83%, 2.40 GHz:0,26%, 2.00 GHz:0,17%, 1.70 GHz:0,23%, 1.40 GHz:92,51% (1415
    So this is the problem, how can I throttle the CPU down to less than 1400?

    Thanks in advance to all

  2. #2
    Linux Guru Rubberman's Avatar
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    You might check into the cpuspeed tool. Here is a link to the cpuspeed web site for more information: CPUSpeed - carlthompson.net

    Most modern Linux systems, especially ones aimed at the mobile market, will already include this tool - RHEL 6 does for instance. If not, then you can either find it in the system repositories or download it from the web site and install it yourself.
    Sometimes, real fast is almost as good as real time.
    Just remember, Semper Gumbi - always be flexible!

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    That is sure a nice tool, but doesn't change the fact that the kernel does only allow 1400 minimum

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    Linux Guru Rubberman's Avatar
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    Hmmm. One approach would be to get the kernel source for your system, and reconfigure it to allow lower clock speeds. So, you are saying that the tool cannot force the CPU under 1.4GHz? You may need to lower the voltage levels also, but do some research about that first so you don't accidentally damage your system.
    Sometimes, real fast is almost as good as real time.
    Just remember, Semper Gumbi - always be flexible!

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    Linux Guru Rubberman's Avatar
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    I did some more research and found the cpufrequtils package that should allow you to interface with the kernel (probably via the /sys subsystem) to better control the speed. What distribution+version+kernel are you running?

    So, when you install the package, it places some kernel modules in /lib/modules for your kernel that you can insmod to get this control. Here is a Red Hat article about this: https://access.redhat.com/site/docum...req_setup.html

    Your system may differ slightly, but this will help point you in the right direction.
    Sometimes, real fast is almost as good as real time.
    Just remember, Semper Gumbi - always be flexible!

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    That's exactly the tool I was using first, which outputs the minimum frequency of 1400.

    Well I will stick to Win7 then. It may be ok to play tool time on some pc at home, but this laptop I need for serious stuff and some trial and error manipulated kernel which might crash the system is not what I will trust in

    But thanks very much for your effort, I appreciate it!

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    Linux Guru Rubberman's Avatar
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    Quote Originally Posted by Wrzlbrmpft View Post
    That's exactly the tool I was using first, which outputs the minimum frequency of 1400.

    Well I will stick to Win7 then. It may be ok to play tool time on some pc at home, but this laptop I need for serious stuff and some trial and error manipulated kernel which might crash the system is not what I will trust in

    But thanks very much for your effort, I appreciate it!
    Well, there is an alternative. You can install a VM manager such as VirtualBox on Win7 and install Linux in a virtual machine. That's exactly what I do at work, since most of my work is Linux programming and software design, but the company system came with Win7 pre-installed. It works well for me - I even do big data (hadoop) prototyping in the VM, plus software development, testing, etc.
    Sometimes, real fast is almost as good as real time.
    Just remember, Semper Gumbi - always be flexible!

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