Intel Core i5 750, Core i7 870 Linux Benchmarks

[Kjella]

Conclusion, new core i5/i7 work terribly under Linux. Least that's the only conclusion I can draw compared to everything I read at Anandtech.

Here's their main conclusion:
"I'll start this conclusion with what AMD must do in response to Lynnfield. The Core i5 750 is a great processor at $196, in fact, it's the best quad-core CPU you can buy at that price today. In nearly every case it's faster than AMD's Phenom II X4 965 BE, despite the AMD processor costing almost another $50." (...) "The Core i7 870 gets close enough to the Core i7 975 that I'm having a hard time justifying the LGA-1366 platform at all."

In short, the results I'm seeing here do not make sense. There's not a single case of the many, many Windows benchmarks where the i5 would lose to an triple-core processor.

[Apopas]

These whole benchmarks just compare Intel i5 to Intel i7 CPUs performance and nothimg more

That's the title of the benchmark after all. i5 750 vs i7 870 and not Intel vs AMD.

[lem79]

Phoronix is probably also the only site benchmarking on Linux? And using GCC instead of the Intel C compiler? I don't know if ICC still does dodgey stuff with checking CPU vendor strings etc, or if the version of GCC used doesn't properly support Nehalem ... but the results here should be a genuine representation of what they are. I doubt anyone went to any length to rig these results.

[Dragoran]

What is important to keep in mind though is that Intel Turbo Boost Technology was disabled on the processors during testing, since this functionality had not worked under Linux for increasing the clock frequency but instead appeared to cause some sporadic performance problems.

Err.. what?

Turbo mode does not really depend on the OS, and works fine on my i7 920.
And of course without turbo mode the single threaded performance is not quiet as good as it supposed to be, also comparing apples with oranges (quad vs. triple core) does not make the test very useful.

[suokko]

Phoronix is probably also the only site benchmarking on Linux? And using GCC instead of the Intel C compiler? I don't know if ICC still does dodgey stuff with checking CPU vendor strings etc, or if the version of GCC used doesn't properly support Nehalem ... but the results here should be a genuine representation of what they are. I doubt anyone went to any length to rig these results.

I wouldn't be surprised if icc is still doing some Intel only optimizations. It would be interesting to see difference wiht icc compiled tests to gcc compiled with all icc optimizations enabled. (I think some of optimizations would require some compiler switches.)

gcc has many contributions from amd while Intel only recently started contributing to gcc.

[Apopas]

Conclusion, new core i5/i7 work terribly under Linux.

Or maybe, Phenom work terribly under Windows

[Michael]

The amd tricore was used since that is just what was available...

[Max Spain]

If you look at some of the benchmarks, AMD has tended to be superior in anything involving cryptography, but I am still surprised to see a lowly AMD X3 pwn the bejeezus out of Intel's latest and greatest so frequently

[Ant P.]

Phoronix is probably also the only site benchmarking on Linux? And using GCC instead of the Intel C compiler? I don't know if ICC still does dodgey stuff with checking CPU vendor strings etc, or if the version of GCC used doesn't properly support Nehalem ... but the results here should be a genuine representation of what they are. I doubt anyone went to any length to rig these results.

If the i5/i7 are getting beaten by a Phenom II just because it's GCC, then maybe Intel should start contributing to GCC... considering it's what 99.9% of Linux users' software is built with.

[StringCheesian]

There's more info on page 4 of the motherboard review:

On some test runs with the Phoronix Test Suite the Lynnfield processors would run very well, but when running the tests again just seconds later, the performance results would be wildly and severely impaired.

[...] core frequencies never increased to their Intel Turbo Boost frequencies when they were encountering a load. Intel's Turbo Boost Technology was not working under Linux. Once we disabled Turbo Boost from the BIOS, our sporadic performance problems were eliminated too. The performance numbers stopped fluctuating and dropping so much between runs and there were finally stable performance figures. Turbo Boost never boosted the performance under Linux or even the frequencies for that matter, but just seemed to cause some problems in our early testing.

Dragoran and other i7 owners, can any of you verify that your i7 is overclocking one or two cores when it should while running linux?