RWT: What is so compelling about Linux for HPC and research computing; in the past, Tru64 or IRIX were the OSes of choice?
Jason: I think the most compelling aspect to Linux for HPC is the access to source and the ability to collaborate with other researchers using different hardware. This was not impossible in the past but it was certainly much more cumbersome. More than likely if you were sharing code between two large scientific computing facilities it meant you had to deal with a different UNIX variant, different development tools, and different processor technologies. Linux in combination with industry standard processors like Itanium and Pentium ease collaboration by providing a de-facto standard of hardware and operating systems available from a variety of vendors.
RWT: Are most of NASA’s key applications written in house?
Jason: There are very few commercial applications that scale to the level of today’s supercomputing centers so most of the codes utilized are “roll-your-own” codes. In addition to homegrown codes unique to their mission, NASA also utilizes public domain codes many of which they have contributed to and are used in the global HPC community; the ECCO ocean simulation model is one such example.
RWT: Which Linux distribution is being used with Altix systems?
Jason: SGI provides choice of two Linux distributions on Altix server (1) SGI Advanced Linux Environment + SGI ProPack, and (2) SUSE LINUX Enterprise Server.
SGI Advanced Linux Environment is an SGI created distribution that is 100% binary compatible with Red Hat Enterprise Linux AS 2.1, which is currently based on a 2.4.22 kernel. Over the next few months we expect to be updating the distribution to be compatible with AS 3.0.
SGI ProPack is a set of open source and proprietary enhancements developed to deliver optimized performance for HPC applications and provide resource management tools for NUMA systems. These include programming libraries, such as our SCSL math libraries and MPT our MPI library. Also included are our CPUsets and dplace tools that allow the user to manage memory and process placement within the system.
SUSE LINUX Enterprise Server is also supported and runs unaltered on Altix starting with SUSE LINUX Enterprise Server 8 (SLES8) service pack 3. SUSE has real technical leadership as a company and distribution and have willingly worked with us to support scalable Linux. In fact SLES 8 supports 64-processor scalability on Altix out of the box, and SUSE has indicated they would like to continue working with us to support even greater scalability. The purpose of SUSE on Altix is to enable user who have standardized on SUSE to deploy Altix easily, and to provide additional certified ISV applications on Altix.
RWT: It seems like a lot of the 2.5/2.6 kernel enhancements were backported to 2.4, when will SGI begin using the 2.5/2.6 kernels?
Jason: We plan to initially make a 2.6 kernel available as a unsupported option for our users starting in the May timeframe. I expect we will have a fair number of our users try it and provide us with feedback on its initial performance and areas where we can make some improvements. We currently intend to fully support both the 2.4 and 2.6 kernel by the end of the year, and expect to eventually phase out 2.4 kernel support over the course of 2005.
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