Benchmarking The Linux 2.6.24 Through 2.6.29 Kernels

[Kano]

I only tested OpenSSL, because i know of the extreme diffs between 32+64 bit. But in your article you stated that you used 64 bit for all. Then those values are extra low.

[lsatenstein]

I would be very interested to know if the current applications (graphmagik ffmpeg, etc.) were compiled with the compiler in use at the time the kernel was created.

I understand, that Intel has an optimising C compiler that produces substantially faster code then does gcc. Since the bulk of installations are on Intel / AMD platforms, it would be interesting to have a comparison of the last kernel and one compiled with Intel's C compiler.

[Nexus6]

I understand, that Intel has an optimising C compiler that produces substantially faster code then does gcc.

I think you'd be surprised at the performance difference between GCC 4.x and ICPC 10.x compiled code. It's not as huge as you might expect - in mixed workloads, I've typically seen anything from GCC being a couple of percent faster to 5-6% slower. I'm certain that there are cases where icpc does outperform GCC by a larger margin but I've not seen it on large projects. GCC has come a long way towards smarter and more extensive optimisation in the 4.x series.

[Kano]

So last live test i made was using 2.6.29 - 32 bit, but even that was only 35.2. High values only possible with 64 bit, but so low values that you have got for OpenSSL are more or less impossible for a 64 bit system.

[Wyatt]

I'm certain that there are cases where icc does outperform GCC by a larger margin but I've not seen it on large projects.

Large projects like FFmpeg?

[smitty3268]

Large projects like FFmpeg?

That test had icc compiling to the 686 target and gcc targeting 486 (i think) so it's not exactly a fair test. Although it wouldn't surprise me if it did still win by a big margin.

[Wyatt]

That test had icc compiling to the 686 target and gcc targeting 486 (i think) so it's not exactly a fair test. Although it wouldn't surprise me if it did still win by a big margin.

Turns out Mike noticed that, too. Seems my bookmark is obseleted by this third post; looks like if you feel like running in the danger zone, there's some improvements in line for GCC. But I don't know many people that commonly run trunk code for their compiler.... :/