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Thread: Intel Core i5 750, Core i7 870 Linux Benchmarks

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  1. #11
    Join Date
    Dec 2007
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    Bucharest, Romania
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    71

    Default These results can not be trusted

    There is something deeply wrong with the results of this benchmark! While the apparent wins of AMD processors can be attributed to anything from poor compiler support to the wild difference in platforms, there is no explanation for the unnatural balance of the Intel processors among themselves!

    While the i7 920 coming out on top in so many benchmarks starts to feel fishy, seeing the i5 750 beat any of the other Intels is clearly wrong, and casts doubt on the whole test! I think the performance problems hinted in the beginning are definitely not solved by turning Turbo Mode off in the BIOS, and further investigation is necessary.

    Perhaps these lines from the dmesg in the previous P55 article give an indication:

    Code:
    ACPI Warning: \_PR_.CPU0._PSS: Return type mismatch - found Integer, expected Package 20090521 nspredef-940
     [ 0.781763] ACPI: Invalid _PSS data
     [ 0.781855] [Firmware Bug]: BIOS needs update for CPU frequency support
     [ 0.781897] ACPI Warning: \_PR_.CPU2._PSS: Return type mismatch - found Integer, expected Package 20090521 nspredef-940
     [ 0.781900] ACPI: Invalid _PSS data
     [ 0.782000] [Firmware Bug]: BIOS needs update for CPU frequency support
     [ 0.782040] ACPI Warning: \_PR_.CPU4._PSS: Return type mismatch - found Integer, expected Package 20090521 nspredef-940
     [ 0.782044] ACPI: Invalid _PSS data
     [ 0.782140] [Firmware Bug]: BIOS needs update for CPU frequency support
     [ 0.782180] ACPI Warning: \_PR_.CPU6._PSS: Return type mismatch - found Integer, expected Package 20090521 nspredef-940
     [ 0.782184] ACPI: Invalid _PSS data
     [ 0.782283] [Firmware Bug]: BIOS needs update for CPU frequency support
    There is also a factual error in the article: the i7 870 is most definitely not a "mid-range" processor, it is running at 2.93Ghz not 2.66 (that's the 750) and has a price of ~550$, not 250$ -- that's the i7 860. There is even an Amazon link that lists the price at 695$ (obviously inflated to get early-adopters). At that price, it would be foolish for Intel to try and sell the 870 if the 920 out-performed it, now wouldn't it?! Of course, every other benchmark everywhere places the 870 far ahead of the 920, it's obvious even from the frequency difference (2.93 vs. 2.66) that the 870 should do better! As it stands, the results of this particular benchmark can not be trusted -- except as indication of something very wrong with the new Core iX processors in Linux, which warrants a closer look.

    Oh, and why is there no mention in either the P55 or this article about the other important change on the Lynnfields, integrating the PCI-E controller with 16x lanes on the processor die? That's the reason the QPI link was replaced by the slower DMI, and in itself could pose tricky problems for drivers and kernel developers, again an avenue of inquiry for the strange results of the tests.

    Regards,
    Mihnea
    Last edited by mgc8; 09-08-2009 at 03:00 PM.

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