This is the time of year to take stock in where high-performance computing (HPC) sits and where it is headed. That's because the SC09 conference is taking place in Portland, Ore., this week and it's the biggest HPC conference around.
SC is an odd duck as conferences go. Last year it had more than 10,000 attendees and, yet, it's a largely volunteer-organized event in a world where trade shows of this scope are packaged by conference specialists or some specific corporation. Think the much-renamed LinuxWorld (run by IDG) or VMworld (run by VMware).
"SC" comes from supercomputing. Today's large computer complexes are typically not supercomputers in the sense of a specialized architecture only suitable for a specific type of technical computing. Rather, as Ashlee Vance notes in The New York Times, "The supercomputing world was long dominated by systems that required specialized chips, memory systems and networking technology. But about 10 years ago, researchers realized they could link thousands of cheaper machines running on mainstream chips and achieve pretty solid performance."
Thus an HPC event is no longer about supercomputers per se (although the term is still used as a convenient moniker for a collection of resources managed as a single entity in a single location). Rather it's about the computing components, the interconnects, the storage, and the software that ties everything together and the applications that run on top.
The Top500 nicely illustrates the evolution of HPC over time. This list, released twice annually, ranks the largest publicly acknowledged supercomputers--as the term is used today--on the basis of a somewhat simplistic, but objective, benchmark. The Top500 entries are certainly not typical of mainstream HPC; they're the biggest of the big. But they nonetheless provide some quantitative insight into important trends.
The newest iteration of the list was released Friday. There were no striking departures from the trends of the last few years, but there was some continued evolution that's worth taking note of.
The continued rise of InfiniBand. InfiniBand is a system interconnect that offers a higher performance alterative to the ubiquitous Ethernet. Although its initial backers envisioned a broader role for the technology, it's settled nicely into HPC and, to a lesser degree, back-end commercial data center functions like database clusters where low latency and high bandwidth are also paramount. (The Sun/Oracle Exadata appliance uses InfiniBand for example.)
(Credit:
TOP500.org)
InfiniBand's initial growth in HPC wasn't so much about displacing Ethernet as it was displacing the fractured collection of high-performance interconnects that preceded it. Myricom's Myrinet and Quadrics' QsNet were the most common of these, but there were many. This year InfiniBand is deployed on 181 of the Top500, a 28 percent increase from a year ago.
That's a striking increase clearly. But what is perhaps more striking is that about half that increase came at the expense of Ethernet rather than mopping up a variety of older or proprietary connection technologies. This shift started between 2007 and 2008 but was even more pronounced this year.
It's certainly possible that the next 10GbE generation of Ethernet, which today is essentially absent from the list, could again push Ethernet's numbers higher. However, whatever the specific technology, the message that I take away is that large computer clusters are starting to favor more optimized interconnects even if they and the components they connect are largely off-the-shelf.
And we see an analogous trend with the proliferation of blade servers as well. Blades, a more modular and pluggable approach to system design, have proven popular in many enterprises and midmarket companies, in part, because they help bring together computing, storage, and networking technologies into a single integrated whole. That type of integration isn't of much interest in HPC. Rather, blades play to HPC by offering high densities and reducing cable count and complexity.
In fact, among x86 servers at any rate, dominance is not too strong a word to describe the presence blades in the Top500. Consider just one vendor, Hewlett-Packard. HP has 208 ProLiant systems on the list. A full 203 of these, almost 98 percent, are ProLiant c-Class blades.
Collectively, these trends suggest what might be thought of as a trend toward building optimization around standardization. In the main, especially as one moves down from the very top of the list, the Top500 is composed mostly of systems using mainstream technologies such as x86, Linux, and standard interconnects. Clusters are the dominant architecture.
But we're increasingly not seeing mere rackmount servers connected by Gigabit Ethernet. As the systems on the Top500 list grow in capability, we're seeing more focus on how they're packaged, powered, and connected.
At some point during the flight over the Pacific from Tokyo, I seriously questioned my decision to take a detour rather than heading straight to Boston and home. It wasn't that I had no interest in attending the Supercomputing show, SC08, being held in Austin last week. It's just that I was coming off of what was already a two-week trip to Japan. However, Supercomputing has been getting more and more buzz in recent years--and I hadn't been able to attend previously because of conflicts--so duty beckoned.
I was glad I made it. It was an immensely interesting and educational (albeit exhausting) couple of days. What follows are a few things that caught my eyes and ears. I plan to follow up on at least some of these in more depth when I have a chance.
Energy and attendees. First of all it's worth noting the general ambience of the show. It was hopping. Economic slump you say? One wouldn't know it from walking the exhibit floor or attending the sessions. To be sure, both booth and attendance commitments are often made well in advance. Nonetheless, I find it striking that SC08 set an attendance record--over 10,000 people--and that a lot of the exhibitors I spoke with were not only happy about the level of traffic to their booths and meetings, but were, in many cases, actually closing business. I found the general feel of the show to be at least somewhat reminiscent of a long-ago UniForum--albeit with more of an academic and application flavor.
InfiniBand is very much alive. I wrote after the October TechForum '08 event that "InfiniBand may not ever markedly expand on the sorts of roles that it plays. But 10 Gigabit Ethernet is far from ready to take over when latency has to be lowest and bandwidth has to be highest." The biggest of those roles is high-performance computing (HPC) and, indeed, InfiniBand was omnipresent at SC08. No particular surprise there but certainly lots of confirmation that InfiniBand is anything but dead. Also significant was QLogic's announcement at the show of an InfiniBand switch family. What's notable is that these switches use QLogic's own chips, rather than sourcing them from Mellanox as everyone else does. That QLogic made this design investment must count as a considerable vote of confidence in InfiniBand's future.
Clusters continue their advance. Supercomputers used to be largely bespoke hardware designs specifically constructed for HPC tasks. There's still some of that. IBM's Blue Gene is one example. A start-up, SiCortex, exhibiting at the show provides another. However, in the main, supercomputing continues to be more and more about clustering together many--mostly standard off-the-shelf--rackmount or blade servers rather than creating monolithic specialized systems. This isn't a new trend, but it continues apace (and is certainly one of the reasons that InfiniBand has been regaining visibility of late).
Microsoft makes modest gains. Microsoft made it into the top 10 of the (publicly acknowledged) largest supercomputers with the Dawning 500A at the Shanghai Supercomputer Center. There was still far more Linux--and, to a lesser degree, other flavors of Unix--at the show than Windows. But this example and others help to reinforce the notion that Microsoft products are technically capable of playing in HPC. That's not to say that Microsoft will easily insert itself into environments that are predisposed to and have in-house skills aligned with Unix tools and techniques. However, as HPC in commercial environments becomes increasingly common, it means that Microsoft has an opportunity there, where Windows typically already has a footprint.
Parallel programming is still a challenge. So much so that all-around computing guru David Patterson devoted his plenary session to the topic. That said, based on Patterson's session as well as the work of a variety of companies such as RapidMind and Pervasive Software, we may be starting to see at least the outlines of how developing for processors with many cores and for amalgams of many systems might progress. The issue is that parallel programming is hard and most people can't do it. One approach is training but we seem to be developing a consensus that neither this nor new programming tools (e.g., languages) really get to the heart of the matter. Rather, the general direction seems to be toward something you might call multicore virtualization--the abstraction of parallel complexities by carefully crafted algorithms and runtimes that handle most of the heavy lifting. (MapReduce is a good example of the sort of thing I'm talking about.)
Supercomputing and HPC used to be their own world. Increasingly they illuminate the future direction of all (or at least most) computing--including the challenges ahead. That's a big reason that I find Supercomputing such a fascinating show.
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