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Intel's New Compiler Boosts Transmeta's Crusoe

Posted by timothy on from the take-that-archenemy dept.

Bram Stolk writes: "Intel recently released its new C++ compiler for linux. I've been testing it on my TM5600 Crusoe. Ironically, it turns out that Transmeta's arch nemesis, Intel, provides the tools to really unlock Crusoe's full potential on linux." It doesn't support all of gcc's extensions, so Intel's compiler can't compile the Linux kernel yet, but choice is nice.

7 of 272 comments (clear)

  1. My results with Linux and NetBSD by Walter+Bell · · Score: 5, Interesting
    The Linux results were interesting, but rather flat: everything benefited from it on my system. However I rebooted into NetBSD and gave the compiler a shot at 'make sys' and 'make world'. Because the NetBSD kernel does not use any nonstandard gcc extensions, it compiled just fine with the new compiler. What I found was:
    • The kernel showed a marked performance benefit on the TM5600. On my TM5400 the results were not noticable.
    • Most userspace utilities appeared to be quite a bit faster on both CPUs. However, some (one notable example being /usr/local/bin/perl) were much slower with the new compiler. I verified that this was not the case on Linux, so it is unclear to me as to why this happens under NetBSD. Further investigation is needed.

    ~wally

  2. next version will do the kernel by grover · · Score: 5, Informative

    ...because this is the first question everyone asks as soon as they find out Intel's compiler works on Linux. ;-)

    I'm not surprised the compiler helped Crusoe. GCC is a remarkable achievement in portability, but architecture-tailored compilers (MSVC, ICC) do better both in terms of code size and speed - like 30% better. But if you're going to PAY for your compiler, it better not be beaten by a free alternative.

    I hope we see distros using icc, and I also hope it spurs further development in GCC.

  3. screw the kernel, recompile the system libraries! by brer_rabbit · · Score: 5, Insightful

    I wonder if Intel's compiler is binary compatible with gcc. While it's probably against the licensing to redistribute the compiler's math or C library, I wonder if you could compile the gnu math/C library with icc and produce a shared object? An optimized math or other system library would give some decent improvement in performance.

  4. Re:GCC extensions?? by wmshub · · Score: 5, Informative
    Yes, the kernel uses enormous numbers of GCC extensions. It gets significant performance improvements this way. Perhaps you are willing to give up kernel performance for a portability, but from my experience as an instructor in a Linux device drivers class, you are in the vast minority. A kernel really needs assembly inlines (for example the sti and cli instructions are get inserted pretty frequently in critical code paths), and to do them well you have to use extensions to C.

    There are even some places where GCC extensions make the code easier to maintain. For example, the way that device driver entry points are defined is much cleaner (using the "structure member : value" structure initialization syntax) and less error prone than using standard C.

    Yes, it might have been helpful a few times to have been able to compile Linux on a non-GCC compiler, but not very often. And GCC runs almost everywhere, so limiting yourself to GCC doesn't limit the architectures you can port to. It really does seem that in this case the benefits outweigh the losses.

  5. Re:Without the kernel, what good is it? by Sentry21 · · Score: 5, Insightful

    So, again, until you can actually compile the kernel, it's a fascinating breakthrough, but one with little utility to the real world.

    So what you're saying is that the only really useful use of a compiler is to compile the Linux kernel?

    That's quite possibly the silliest thing I've heard someone say. Try:

    Son: "Look ma, I got the fastest engine in the world for my car! Now I can drive faster than anyone else!"

    Ma: "Um, sonny, it can't play MIDI files or make julean fries, so it's totally useless."

    Totally wrong. There are thousands of pieces of software out there. The Linux kernel is merely one.

    --Dan

  6. Wrong... by Carnage4Life · · Score: 5, Informative

    What if, besides caruso, Intel's compiler is actually a BETTER compiler than gcc on intel hardware? Then were stuck using gcc for compiling the kernel when something better is or might be some day available. . Locking the kernel to a compiler is a BAD THING[tm].

    The Linux kernel is not only available on Intel chips. It is available on ARMs, DEC Alphas, SUN Sparcs, M68000 machines (like Atari and
    & Amiga), MIPS and PowerPC, as well as IBM mainframes.

    Which makes more sense? Targetting a cross plartform compiler like gcc are targetting individiual compilers for each platform Linux runs on?

  7. Results not surprising by jgarzik · · Score: 5, Informative
    These are not surprising results. Even the gcc developers will admit that many general, not-architecture-specific optimizations done by commercial compilers are not performed in gcc. Most new CPUs, not just Intel CPUs, can benefit from a smarter compiler to take advantage of features like data prefetching, instruction bundling and pipelining, profile-based (feedback-based) optimization, data and control speculation, and much more.

    The gcc "open projects" page gives people a good idea of what remains to be done on gcc. The minutes of the IA-64 GCC summit are especially interesting and informative, because it gives a good idea of the current state of GCC and also what GCC needs to be a competitive compiler in the future.

    Bottom line: Do not be surprised when commercial compilers beat gcc performance. It's catching up, but it's still got a long way to go.

    GCC Home Page