Floating Point & Compilers

When looking at floating point performance we also tried out different compiler settings.

C-ray rendering at 3840x2160 - Compiler comparison

But nothing we tried gave us better results than GCC with the "-O3" setting. It looks like that setting is very effective as it almost doubles performance compared to "-O2". Once again, the XLC compiler fails to deliver any speed boost. In fact, XLC compiled code is slower than GCC 4.9.

Floating Point: Raytracing Floating Point: NAMD
Comments Locked

146 Comments

View All Comments

  • joegee - Thursday, November 19, 2015 - link

    It was an awesome community. I learned so much from everyone. I remember the days when we'd write pages arguing whether AMD's new 64 bit extension to x86 was truly 64 bit. The discussions could be heated, but they were seldom rude. I wish there were something similar today. :/
  • Kevin G - Saturday, November 7, 2015 - link

    Aces brings back memories for me as well even though I mainly lurked there.

    A solid chunk of that group have moved over to RWT.
  • joegee - Thursday, November 19, 2015 - link

    What is RWT?
  • psychobriggsy - Friday, November 6, 2015 - link

    Get back to Aces Hardware you!
  • JohanAnandtech - Saturday, November 7, 2015 - link

    Like Ryan said, I have been working 11 years at Anand. In other words, it is great working at Anandtech. AT is one of the few tech sites out there that still values deep analysis and allows the editors to take the time to delve deep.
  • joegee - Friday, November 6, 2015 - link

    And still writing as well as you ever did! Keep up the good work, Johan!
  • rrossi - Saturday, November 7, 2015 - link

    Dear Johan nice article. Did u ever consider sparse system solving (with preconditioning) as a sensitive benchmark? It is a crucial stage of most scientific applications and it is a bandwidth limited operation with a high degree of parallelism. It would be definitely interesting to see how the power 8 fares on such a test. If you are interested I think I could provide a pointer to a simple benchmark (to be compiled). If you feel it may be interesting just drop me an email.
  • JohanAnandtech - Saturday, November 7, 2015 - link

    Interested... mail me, I don't have your mail. See the author link on top of the article.
  • Ian Cutress - Saturday, November 7, 2015 - link

    I'd also like to be pointed to such a benchmark for workstation style tests on x86. Please email ian@anandtech.com with info :)
  • MartinT - Friday, November 6, 2015 - link

    Johan's been with Anandtech for more than a decade, and has been publishing on the subject since the late 90s.

    But I very much second your "Niiiiice!," as reading his name always reminds me of the old days over at aceshardware, and I'm always looking forward to his insights!

Log in

Don't have an account? Sign up now