Slashdot Mirror

← Back to Stories (view on slashdot.org)

How to get 1.5 TeraFlops from Linux

Posted by CmdrTaco on from the squeeze-out-the-flops dept.

Oak Ridge National Lab has purchased from SGI an Altix 3000 (flash movie). This article claims that: SGI Altix 3000 is recognized as the first Linux cluster that scales up to 64 processors within each node and the first cluster ever to allow global shared memory access across nodes. There is more here, here, and here.

6 of 280 comments (clear)

  1. Better than Beowulf for normal use... by TWX · · Score: 5, Informative

    You're better off using mosix. It'll allow for more normal (ie, not beowulf specific) applications to thread across computers. I'd imagine that an open-mosix setup (like the ones using the knoppix boot CDs tailored to it) could probably make for a fairly powerful computing cluster very easily.

    --
    Do not look into laser with remaining eye.
    1. Re:Better than Beowulf for normal use... by ERJ · · Score: 5, Informative

      Mosix is nice, because it treats the cluster like a single, large, multi-cpu box by simply allocating threads to different boxes. The nice thing about this is that any multi-threaded program can take advantage (as stated in the parent post).

      However, this also can cause problems. Most threaded programs are written assuming that all the threads have high speed (i.e. system bus / cpu cache) access to shared information. When we introduce the latency incurred by a network, this can cause programs to run alot slower then they would if they simply had all the threads on a single box. Obviously, it all depends on how the program was written, and what it does.

      If you are writting a program specifically for a cluster, I would suggest instead looking at something like LAM-MPI. This allows for a much more controlling approach to be taken. It is more work (you have to decide how the work will be split) but it allows for much better control of where and what is being done and how to optimize it.

  2. Re:Beowulf cluster jokes... by gladbach · · Score: 5, Informative

    just download clusterknoppix and knock yourself out. ; )

    http://bofh.be/clusterknoppix/

    --
    "Computer games don't affect kids; I mean if Pac-Man affected us as kids, we'd all be running around in darkened rooms,
  3. Re:Beowulf cluster jokes... by The_ForeignEye · · Score: 5, Informative

    Back in my days of parallel programming (read: 1998) on Beowulf clusters I used Fortran and C. The trick to make your program "parallel" is to use special programming libraries that will spawn instances of your program across the cluster and let them communicate between each other. The libraries I used were PVM and MPI.

    At that time they were working on a Java implementation, but I don't know what happened with that.

  4. Oops (RTFA) by Anonymous Coward · · Score: 5, Informative

    The machine has 256 processors for 1.5 teraflops, not 64.

  5. Setting one up now by jimshep · · Score: 5, Informative

    We just got ours installed yesterday. I'm still installing software and am starting benchmarks. It's only the deskside version (12 cpus, 24GB RAM, 1TB disk), but still more powerful than the 4-cpu SGI Origins that we have been using.

    It is the first one that the regional SGI reps had actually installed, but since it is almost exactly the same as the MIPS-based origin 3000 servers (with the exception of the obviously different Itanium 2 cpus and supporting chipsets), they ran into almost no problems getting it online. I have also been suprised as to how many commercial codes have already been ported to the platform.

    The main reasons we purchased this machine is for the ease in parallelizing code and the floating point performance of the Itaniam 2 cpus. We're computational materials engineers and the less time we have to spend optimizing codes so that the nodes of a cluster are always kept busy and minimizing I/O bottlenecks gives us more time to concentrate on the theoretical issues.

    It runs RedHat 7.2 with some tweaks by SGI called SGI ProPack. The Propack modifications come on separate CDs, with the proprietary software on separate CDs from the open source software. So far, from the command line, everything works just like my PC. It's kind of strange running Linux on a >$100K machine, but it sure beats dealing with the annoying differences between IRIX and Linux. Now to see if it performs as well as we expect...