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Thread: Intel Linux Power Regression Still Being Worked On

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    Default Intel Linux Power Regression Still Being Worked On

    Phoronix: Intel Linux Power Regression Still Being Worked On

    A few days back I wrote about an Intel Linux developer finding a 50 Watt power regression within the kernel since the 3.10 release. At first it looked like it might be easily solved, but the issue is still being investigated and Intel hardware engineers are now getting involved in the matter...

    http://www.phoronix.com/vr.php?view=MTU0MTc

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    I think it's dishonest or at best misleading to call it a 50 watt power regression. Most people who read that will assume that it's 50 watts on one processor. But in fact, it's 50 watts over 40 xeon cores. Assuming these are quad core CPUs then it's more like a 5 watt power regression.

    I get that it's a lot more attention grabbing with bigger numbers, but please try not to do this.

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    Quote Originally Posted by papper View Post
    I think it's dishonest or at best misleading to call it a 50 watt power regression. Most people who read that will assume that it's 50 watts on one processor. But in fact, it's 50 watts over 40 xeon cores. Assuming these are quad core CPUs then it's more like a 5 watt power regression.

    I get that it's a lot more attention grabbing with bigger numbers, but please try not to do this.
    One of the other mailing-listers piped in that he was seeing I think it was a 25watt difference on a quad core system so its not a "5 watt regression" its a 50watt regression on a 40core system, but that ratio isn't linear

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    Quote Originally Posted by Ericg View Post
    One of the other mailing-listers piped in that he was seeing I think it was a 25watt difference on a quad core system so its not a "5 watt regression" its a 50watt regression on a 40core system, but that ratio isn't linear
    Maybe then there should be tests on common dual- and quad-core systems to determine the power hit and then make the decision whether its severe enough to correct. 50 watts over 40 cores seems to be relatively minimal

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    Quote Originally Posted by papper View Post
    I think it's dishonest or at best misleading to call it a 50 watt power regression. Most people who read that will assume that it's 50 watts on one processor. But in fact, it's 50 watts over 40 xeon cores. Assuming these are quad core CPUs then it's more like a 5 watt power regression.

    I get that it's a lot more attention grabbing with bigger numbers, but please try not to do this.
    Keep in mind that any modern workstation or server usually ships with 20+ cores which, translates to 25w+.
    Given the fact that my new workstation idles at ~160w, knocking down 25w is nothing to sneeze at.

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    Quote Originally Posted by gilboa View Post
    Keep in mind that any modern workstation or server usually ships with 20+ cores which, translates to 25w+.
    Given the fact that my new workstation idles at ~160w, knocking down 25w is nothing to sneeze at.
    Usually? That's pretty high end.

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    Quote Originally Posted by nils_ View Post
    Usually? That's pretty high end.
    I doubt that a 3,000-6,000$ dual socket server is considered high-end.
    (High-end usually reserved for 15,000$ 4S servers and above).

    Oh, and keep in mind that if you go AMD, the core count is usually 25% more (performance is another matter).

    - Gilboa
    DEV: Intel S2600C0, 2xE52658V2, 32GB, 4x2TB, GTX680, F20/x86_64, Dell U2711.
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    Quote Originally Posted by gilboa View Post
    I doubt that a 3,000-6,000$ dual socket server is considered high-end.
    (High-end usually reserved for 15,000$ 4S servers and above).
    Yeah, but on a dual socket system you only get to 20+ cores by using 10 core / 12 core CPUs. That's not really in the 3-6k price range. Unless you go with AMD but who does that these days? May be different for you but I usually buy 2 Socket Servers with 8 - 12 cores.

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    Quote Originally Posted by nils_ View Post
    Yeah, but on a dual socket system you only get to 20+ cores by using 10 core / 12 core CPUs. That's not really in the 3-6k price range. Unless you go with AMD but who does that these days? May be different for you but I usually buy 2 Socket Servers with 8 - 12 cores.
    We're going OT, but lets do the math:
    - An 8 core Xeon (E5-2640V2) goes for ~900$ or 1800$ for a pair.
    - Intel server platform: ~1300-1400$.
    - Memory: 64GB: ~600-800$.
    - Drives: 200-800$.
    - Total: 3,900$ - 4,800$.

    Now keep in mind that large enterprises / OEMs usually get major discounts.

    - Gilboa
    DEV: Intel S2600C0, 2xE52658V2, 32GB, 4x2TB, GTX680, F20/x86_64, Dell U2711.
    SRV: Intel S5520SC, 2xX5680, 36GB, 4x2TB, GTX550, F20/x86_64, Dell U2412..
    BACK: Tyan Tempest i5400XT, 2xE5335, 8GB, 3x1.5TB, 9800GTX, F20/x86-64.
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    Quote Originally Posted by gilboa View Post
    We're going OT, but lets do the math:
    - An 8 core Xeon (E5-2640V2) goes for ~900$ or 1800$ for a pair.
    That's a 16 core system though, not 20+. It really starts getting expensive when you go over 20.

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