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Cray CTO: Linux clusters don't play in HPC
jagger writes "Linux clustering was touted as the next big thing by many vendors last week at ClusterWorld Conference & Expo 2004. But supercomputer vendor Cray Inc. scoffed at the notion of putting Linux clusters in the high-performance computing (HPC) category. "Despite assertions made by Linux vendors, a Linux cluster is not a high performance computer," said Dr. Paul Terry, CTO of Cray Canada."
While Paul Terry makes some good points, in his statements, including the partial quote from the post, "Despite assertions made by Linux vendors, a Linux cluster is not a high performance computer, said Dr. Paul Terry, CTO of Cray Canada. "At best, clusters are a loose collection of unmanaged, individual, microprocessor-based computers."
Remember to take this with a grain of salt. The inflammatory nature of the comment is nothing more than a marketing ploy to increase visibility of, and sell, the new Cray XD1
Kinetic stupidity has a new brand leader: Allen Zadr.
...a Beowulf... cluster... thingy... doesn't that count?
A quote I've seen before:
"If you were plowing a field, which would you rather use? Two strong oxen or 1024 chickens?"
Maybe he meant penguins?
Nuke Gay Whales for Jesus.
Dr. Terry's assertions remind me of a Seymour Cray quote I had as my
I'm not picking a side, it just seems interesting that the Cray CTO would echo Seymour's thoughts. I guess it's for business and marketting reasons though, sadly.
Trolling is a art,
You did notice he is the CTO of Cray... Canada??
Those who can, do. Those who can't, consult.
Company officer claims competitor isn't as good as his product. Film at 11.
Oracle disclaim MySQL and PostgreSQL as "toy databases", Microsoft claims that "Apache cannot be used for real web serving", and Sun announces that "Intel and Linux simply cannot be used for enterprise computing".
So all those supercomputing labs that use Linux clustering (that invented Linux clustering, even) have been wasting their time?
Ceci n'est pas une signature
I guess that the simple problem is just that the algorithm applied is usually not suitable for massively parallel computing.
Regardless of whether I agree with the article or not I feel compelled to point out that:
The 1100 node Apple G5 cluster in virginia has yet to run any real scientific code. So far it has only ran benchmarks.
"We are dropping our line of Cray supercomputers and replacing them with rack mounted Beowulf cluster of 486's!"
I am not saying Cray isn't worth it, but there is something to be said on replacing/fixing your supercomputer with over the counter parts.
REading the article it's fairly obvious that Cray's CTO has an agenda, however, assuming he's right, what does play in HPC? Cray Prorpritary Cluser OS (TM) or what?
In other news...
"Despite assertions made by Toyota salesmen, a Lexus sedan is not a luxury car," said Bill Taylor, CEO of Mercedes-Benz.
This space intentionally left blank.
Clusters can get high performance on some types of tasks. But sometimes, you need fine-grained parallelism that just isn't available on a cluster.
On the other hand, high performance usually comes through special hardware. And on that hardware, I think Linux could be the right thing (modulo some patches).
A message from the system administrator: 'I've upped my priority. Now up yours.'
Now, if the CTO of Cray Canada started talking about your mother than I think you're morally entitled and required to respond.
It's not the vendors who are claiming that Linux clusters are real supercomputers, it's the people who are using them to do real supercomputer work. They sell themselves based on actual price and performance.
Methinks Cray is feeling a little threatened...
"Despite assertions made by Linux vendors, a Linux cluster is not a high performance computer,"
Maybe so but not everyone can pull a Cray out of his ass when they need horsepower. A Linux cluster is affordable, a Cray is the thing of wet dreams..
Despite assertions made by Linux vendors, a Linux cluster is not a high performance computer, said Dr. Paul Terry, CTO of Cray Canada. "At best, clusters are a loose collection of unmanaged, individual, microprocessor-based computers."
I guess they're not happy about being only #19 on the Top 500 Supercomputer List. Linux is considered faster than they are according to the list.
The 'ol ad-hominem attack of "if you can't beat them ligitimately, attack them personally" just doesn't cut it Paul. Build a better computer.
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The Cray CTO makes the point that Linux clusters get, at best, just under 10% peak as sustained performance and uses this as a justification that Linux clusters are not HPCs. This is a reasonable criticism. Let's take the percentage he cites as real for a moment. Now what is the cost difference between a Linux cluster and a Cray (not some future offering, but today) and how much more of a Linux cluster could you afford? Would that offset the quoted inefficiency? Would the flexibility of being able to use commodity components further offset any advantage Cray might have? What about 24hr or same-day parts replacement without a hyper-expensive service contract? At the end of the day, I suspect the Linux cluster wins out even given the sub-10% efficiency figure Cray cites. --Pat / zippy@cs.brandeis.edu
well i guess now we'll have to add them to the list...after SCO and Microsoft of course
Wish I'd been there so I could have slapped him after about 3 seconds of stunned silence.
I'm trying to teach myself to set people on fire with my mind... Is it hot in here?
It all depends on the problem you are trying to solve. I have been doing some work of late that would not complete in my life time on the 108 node cluster that we have. But when programmed for and run on two Cray X1s I should complete inside of a week.
Granted there are many codes (and more every day) that will run on clusters, the big iron will never die.
Just because we love Lunux doesn't mean that clusters are HPCs.
There are real issues that differentiate mainframe/supercomputers from large, powerful, clusters.
Of course this all depends on your definition of an HPC. But I believe that it's reasonable to say that if parts of your computer are connected with low bandwidth connections (10/100,gigabit) they just can't handle the same kinds of transactions that a computer with parts that are connected by 10 gigabit or 1000 gigabit connections or whatever it is nowadays.
As far as I know if you're deploying a large database it's still advisable to have a big huge IBM mainframe or a Unisys box or a Sun 10k instead of 4,8 or 16 clustered 8 proc machines.
My point is there are valid arguments for not including clusters of commodity hardware in the HPC category.
In my mind they aren't High Performance Computers... they are High Performance Clusters of Commodity Computers.
~foooo
Where's your God now hippies? Where's your God now?
How well a cluster will do depends on the application that it is performing. Some problems can be divided into several small problems with little reliance on other parts of the problem (SETI / Encryption breaking). These things can be easily distributed to hundreds or thousands of "small" boxes for processing and are what a beowulf cluster would be good at.
Other applications require the breakneck interconnect speeds that large Cray / Sun / etc.. build on. When the data being calculated on one CPU requires data from CPU2 to continue its calculations you don't want to have it wait for 100mbit or even 1gbit ethernet speeds. Even quicker interconnects such as SCALI are going to be slowed by PC bus speeds.
Cray fills an important niche for those who can afford it.
The comment was stupid, yes, but not all jobs that you'd use supercomputers for can be broken down into many threads as others can. A linux cluster will do well for some jobs, a cray box will do well for others. There *will* be times when a Cray system is so far superior to anything you could do with Linux that it becomes the only real option.
However, dismissing linux cluster technology automatically is dumb. In many cases, it provides more than enough cpu power and I/O bandwith to support your reason for getting a supercomputer, and probably at less cost than the other options.
Its all a matter of determining what you need the computer to do, determining your budget, and get the best system in your budget for the uses you have for it. Sometimes that will be a Cray, sometimes a Linux cluster.
Who is this guy and what does a company like Cray know about... oh... never mind.
Clusters can rival a supercomupter when they are assigned is a task that's suitable for distributed computing. That is, work units can be divided up and worked on in any sequence... the result of segment 45 doesn't depend on knowing the result of 44 and such. Effectively, you can have the sum of all of the processors minus just a little overhead for the clustering.
What Cray's rightfully pointing out is that for most business applications, however, distributed computing is not a viable option. When processing on a transaction basis, the transactions often need to posted in the exact order they were recieved, which means they must be taken serially. In those situations, the programs can't multithread work out to the other processors so well, and the cluster will end up running at roughly the speed of just one processor while the others waste clock cycles waiting for something to do.
The cluster isn't the solution to everything. Nor is the supercomputer. You've gotta think about the job, then figure out which tool is right for the task.
His rhetoric is quite predictable, actually. He talks at some length about how and why clusters of PCs can't get the job done, and how clustering is inherently inferior to a REAL SuperComputer, then goes on to describe how their new product (which sounds suprisingly like a cluster of propreitary machines) can work. Repeat the above as it applies to the management software.
If clustering doesn't work, and Supers are better / cheaper, explain why large companies (Pixar, NVidia,
Note that this does NOT mean that clusters are suitable for ALL traditional SuperComputing tasks. It really depends on the problem. If the problem is better solved with a vector processor, then a vector machine (like a Cray) is what you want. If the problem is solvable in parallel, then a cluster might be the right answer.
I assume you are refering to the Altix systems. They are Single System Image systems (SSI), when means they are built like a supercomputer, and not like a cluster. They are big and expensive.
SSI is where all CPUs can see all memory as if it was local. They are also Non-uniform memory access which means all the memory it sees is not as fast as all other memory, but really ALL single systems are like this. For example each CPU can address the entire TB of memory that is in the system, but reading from one memory location might take 100 cycles, and from another might be closter to 1000 cycles.
I'm a layman...I have no idea what I talk about, but of course that doesn't stop me.
I know I keep coming back to Virginia Tech, but isn't all those G5's linked together to make the 3rd fastest supercomputer itself a cluster? Or is it considered something else?
And if it IS considered a cluster, then why wouldn't a Linux based (along with the *BSD based G5s) be able to make a fast supercomputer?
If so, then what Paul Terry is spouting is just FUD and marketing to help sell his product, yes?
Just wondering.
"Music is everybody's possession. It's only publishers who think that people own it." - John Lennon.
In truth, such machine will always have a certain performance advantage over traditional clusters. The question is, will the price point be low enough to invalidate the idea of just adding more boxes to the traditional cluster.
"Who are in control, they are not in control of anything - they don't even control themselves!" - Glen Beck
Cray is losing market share and want people to believe that their expensive to maintain and operate machines are better and 'cheaper' than a clusteer of regualar pc's running together. My question is Does anyone with experiance with both systems back him up.
While I certainly disagree that you can't build a very high performance computer out a cluster of computers (Linux or otherwise), there is a lot of merit to the fact that clusters just don't scale well for certain classes of applications. Hence the renaissance of the vector supercomputer (ala the Earth Simulator ).
Obviously, this guy is plugging the new Cray X1 architecture, which really is quite promising. For instance, check out this paper by some folks at Oak Ridge National Lab that appeared in Supercomputing 2003.
Of course, since this is Slashdot, I expect that there will be a deluge of posts decrying everything about the new Cray machine because it commits the cardinal sin of NOT USING LINUX. Oh, the horror!
Octigabay does (did) in fact make linux solutions. However, it is not a cluster. It's a more traditional supercomputer although it does use low cost AMD processors.
Cray isn't anti-linux per se, just anti-cluster.
Somehow I wouldn't be surprised, the next step seems to be cray-marketed cluster nodes with a proprietary high speed interconnect. (If you can't beat them, join them).
The "interconnect" latency (especially) and bandwidth in a cluster, even using very high-end network hardware, is much worse than that of a Cray-style supercomputer. This does make certain applications run slower, especially if not specifically tailored to clustered architecture. Some applications are very difficult to break down into small pieces and require extensive memory sharing between nodes, which clusters just can't do well.
I happen to work in a facility that has large had both large supercomputers (cray t3e, j90, sgi) and linux and *nix based clusters (beowulf/linux, compaq/Tru64). The Cray CTO is correct that you can't just call every linux cluster out there HPC. Just about anyone with networking and linux knowledge can build a linux cluster.
What really makes a difference between an HPC cluster and your normal every day cluster is the hardware interconnects used. There is a comment in the artical that refers to not using I/O for memory and message passing. I am not quite sure what he means by that, but I am guessing that he is saying that the network is not used for shared memory/message passing (MPI/openMP/SHMEM).
If a cluster can limit the impact of latency between nodes either through smarter software or faster interconnects then I can't see any reason not to concider a linux cluster as HPC.
Clusters without smarter software tend to be a real difficult coding platforms. Some developments with things like globally shared memory might make the difference, but there will still be the problem of latency between nodes.
"Despite assertions made by Linux vendors, a Linux cluster is not a high performance computer,"
That's like saying that the automobile is not a high performance team of clydesdales. That's true, but it may be irrelevant. If it can get you there faster or better, I guess it doesn't matter.
Disconnect your television. Do your own research. Draw your own conclusions. They're probably lying. Don't be a sheep.
My friends and I at the university create a beowulf cluster as a project for our Linux class, (just installing software, nothing impressive really, basic system administration) and benchmarked it (24 P200s 32MB ram each 10baseT network) against a reasonably fast computer running the non-parallel version of the same code... (HP C station) and ours finished faster, with the overhead of networking! as to being "a loose collection of unmanaged, individual" We managed it pretty tightly, using nfs to provide the binaries that would be used, thought we did not use NFS for the root partition, as this would put to much stress on our poor fileserving node. If I remember properly, we used dist for password files, and aside from pushing the power switches, we could manage everything in the room without leaving our seats (24 computers running 'xlock -mode matrix" hehe).
Basicly, I disagree with Dr. Terry.
our project writeup is here.
(Please forgive any mistakes or stupiness therein, we were 15, 15, and a 30something non-geek at the time.)
Less look fast, more go fast.
Oh, here's the TOP500 list, btw.
The reason that Cray only holds 19th right now is because they have only deployed X1 systems using up to 256 nodes. When the number of nodes is increased, you will certainly see the Cray moving up the top 500 list -- the architecture is VERY scalable.
Cray wants all forms of clusters disqualifed from that list for not being true supercomputers since they can only consider tasks that support multithreading at their full speed. If given a logical task that must be processed serially, the cluster will end up dropping to the speed of its fastest processor. Sure, the rest of the cluster is available to consider other questions... but the point is, it's going to waste some cycles while a true supercomputer would be able to dedicate its entire resources to the task.
Every task has a maximum number of threads it can be broken into where adding another parallel process threads just won't make it any faster. For some, that number is in the stratosphere and doesn't have to be worried about. However, for others, that number is in the single digits. Those tasks aren't going to be helped much by a cluster that exceeds that number of processors.
For some tasks distributed clusters are better, for others ultra-high-bandwidth Cray-type monsters are better. So what's new?
"'I pass the test,' she said. 'I will diminish, and go into the West, and remain Galadriel.'"
- JRR Tolkien.
but practically, the performanc is "high enough" and certainly a helluva lot cheaper than buying a custom system.
It's just like the old days, except more so:
and you can end up paying a lot of money to squeeze out that extra performance.Given that Linux clusters can achieve speeds in excess of a teraflop, that available dollars for computer purchases are finite, and that per processor performance and price performance is increasing, the market size for the world's highest performing machine is rapidly vanishing to a set of measure zero.
"Provided by the management for your protection."
The Cray XD1 System operating system is Linux
Cray could easily be at or close to the top of the top500 list, their X1 architecture will extend that far. However, for a lot of really important supercomputing codes, it's no contest: The cray will trounce the clusters (linux or otherwise). Those #19 crays are only 256 processors. To get similar performance a stack of xeons requires thousands of processors. Some tasks just can be split appart that easily.
A cray processor has eight floating-point units running at 800Mhz. The big Mac cluster (for example) uses G5 processors which have 2 FPUs at 2000Mhz. Thus the cray has a ~40% advantage. However, the G5 processor has ~4GB/s memory bandwidth. The Cray has ~50GB/s memory bandwidth. If you have a problem that needs to do a HUGE amount of math on a tiny amount of data, the G5 will rock. If you have a problem that needs to do a HUGE amount math on a GINORMOUS amount of data, buy the cray. (for a GINORMOUS amount of money too)
Similaraly infiniband (ala the big mac) is really hot in the cluster interconnect space because it gives 2.5GB/s per node. The Cray gives you 51GB/s.
You need to move a little data, buy a cluster. You need to move a lot of data, buy the Cray.
There's no one solution for all problems.
Cray is dying. The days of fat government sales have been over for a long time. It's only logical to discredit your competitors, especially if you stand to lose a lot because of them.
This is nothing new, nor anything special. For instance, if you've looked at the latest computer magazines, Microsoft is doing the same kind of "it sucks" argument to anything related to Linux in a wide front. For example, Apache lost to IIS in a review, and IIS became the Editor's Choice in one magazine. In the next issue of the magazine there will be somekind of "debunking Linux myths" article. (This certain computer magazine is nothing special, even though it has become a nothing short of an unfunny joke paper written by people who don't have a clue. Some of their readers do have a clue, that's why they cancel their subscription.)
So, to sum it up: it doesn't matter what the reality is, the people who decide only see the image which is created for them. Even if that image is wrong, that's the only thing they decision makers are going to see. They don't have the time or the energy to investigate things thoroughly on their own. This is why Microsoft pays the magazines to write garbage. This is why a Cray executive talks garbage.
Lobbying is pretty powerful stuff.
I do not moderate.
A lot of what he said isn't much of a surprise, however definitive statements about clusters not being supercomputers and being unmanaged loose collections of machines are a bit overblown. Management software exist for clusters and they are rather easy to program for with available popular and industrial strength libraries.
Moreover many HPC applications actually scale quite well on clusters of Linux systems. Affordable interconnect infrastructure is increasing in bandwidth and reducing in latency, further broadening the scope of the problems these clusters can tackle. In addition each node can now comfortably have 2 or four processors giving even better bandwidth between CPUs sharing a node. With 64 bit processors and operating systems now available the final barriers to very impressive easy to use HPC Linux clusters have been removed which is exactly why Cray now sees them as a threat. Now is probably the worst time to talk of how a cluster is not a supercomputer. Clusters form a class of supercomputer that can now handle most supercomputer tasks. True there are classes of problems that the dedicated supercomputer systems CRAY sells will excell at, however clusters are useful workhorses in the supercomputer world and hold their own.
Todays supercomputer problems are tomorrows computer problems and Cray must continue to find new classes of problems to solve as they always have, rather than attacking competing technologies, people will use clusters where the clusters meet their needs.
True Parallele Programming with computer with over 16 or so CPUs is a slightly different mindset then the way most people program. In PP you can write a sort routiene that runs in O(log(x)) While with one processor system you can only do it in O(x). Most programs today that are threaded tend run a buch of code on one processor and its own memory. That is much the way that linux clusters work, by writting programs that minimalize the amount of comunications needed so then they provide high performace. But crays and the like super computer allows all the processors to comunicate with each other and the shared memory a lot faster. Thus making some algorithms run in Maginatudes faser.
An example is when I took a course in Parrallel processing we used a MassPar system which had 1024 processors in a grid formation. Now woring on that system I was able to sort a list of a million random numbers way faster then my Duel Processor PC could.
But on the flip side when I ran a program on the MassPar that wasn't designed parallel processing (emacs) it took upwards of 3 minutes to load it due to the age of the computer. While my PC could open up emacs in a split second. So on the clusters even the fastest in the world a Cray that may not be the fastest could actually beat it on many applications because of the faster bus comunication.
If something is so important that you feel the need to post it on the internet... It probably isn't that important.
You know Goodwin's Law? Well, here is Heironymous' Corollary to Goodwin's Law:
"Anyone using the terms 'zealot' or 'FUD' in a Slashdot discussion is immediately declared the loser of the thread and discussion stops at that point".
Of course I'm force to break my own corollary to make this point.
But to call me a "Linux zealot spouting FUD" (and excuse me for paraphrasing your lucid comment) because I mock a commercial vendor who says that the free alternative is no competition... WTF?
As it happens: I have 20+ years of experience in IT and I've used every one of those packages (except the Cray). Oracle, MySQL, IIS, Apache, Sun, Solaris, Linux. And hundreds of other platforms, as well.
My opinions are not those of a zealot, but pretty impartial and generally very accurate. There is a good reason, for instance, why the most critical servers in my business all run Debian Linux, why the desktops use Xandros, why our applications use MySQL, and why we're phasing our out Microsoft/COM+/IIS/SQLServer platforms. Zealotry has little to do with it, but good sense does.
The facts are these: open source, free, commodity IT has become good and cheap enough to exceed the capabilities (at any price) of many commercial systems. Most specifically, Cray, Oracle, Microsoft, and Sun find themselves spot center of the area that has been commoditized.
Ceci n'est pas une signature
"No, a Kilochicken is a 1000 chickens. You're thinking of a kibichicken. Check it out at http://www.nist.gov" Somebody had to, right? Right?
I'd like to see Paul Terry say this in front of everybody at the Super Computing conference where they announce the Top 500 Computers. Its worth noting that he is not bashing Linux per se, but "Linux Clusters", which is pretty arbitrary, because he should be saying "all clusters", because the OS really doesn't have too much to do with it. Supercomputing apps run in userspace, not kernel space, and the hardware, including interconnects or some kind of interprocessor communication drive the performance.
The Cray XD1 looks like a nice system, but there are only theoretical performance values given, and noone can go out and buy one of these things yet. I also don't know how much these guys cost.
I love this statement:
Linux clusters do have a place. "For applications that require low performance, they are a cheaper solution," said Terry.
Yeah, when we spend a million+ dollars on a supercomputer, we are thinking of low performance, because our applications require it. Thanks.
I'm guessing this guy is a wannabe marketer who got stuck in a CTO position. There are plenty of HPC vendors out there, and trust me if this XD1 has a good price/performance and they work (this is key), then people will buy them with little questions asked. Otherwise, this whole article is just an advertisement that makes many statements without any evidence that the XD1 is any better than 4 Xboxes connected together over a serial connection. Next....
I bet if you asked a lot of computer dilletantes out there what the fastest computer in the world was, they'd still say "Cray 2".
Savages.
doesn't this CTO of cray remind you of someone?
"There IS no Linux in high-performance clusters."
"There IS no Americans in Iraq."
OMG! It's the former Iraqi mis-Informed-ation minister!
Especially when 2004 has been dubbed the year of the penguin, it's wreckless to claim that Linux can't be used in HPC's.
Hell, just look at the current top500 list. There's no Cray in the top 10 but there are two Linux based clusters there (and one based on OSX [FreeBSB based]).
Here's a few:
NCSA's IA32 Linux cluster
NCSA's IA32 Linux cluster
Space Simulator Clust at Los Alamos (SS51G based; makes me proud as I have a SS51G too)
Beowulf - used in many Linux clustering projects
Linux clusters at Los Alamos (they seem to have more than one)
Virginia Tech's Supercomputer X
I have a rack right here housing a linux cluster. 36 1U dual-Xeon servers. On the Cray XD1 site it details the "Exceptional Performance" of the XD1 system. It details the performance of a system with 12 AMD Opteron processors, and the performance of a rack of systems with 12 AMD Opteron processors. I understand that the underlying architecture of those servers may be vastly different than the servers in the rack next to me, but fundementally aren't they both multi-processor PC servers operating in a cluster? If so why does their rack full of multi-processor systems qualify as an HPCbut mine does not?
"We can't solve problems by using the same kind of thinking we used when we created them."
Despite assertions made by Linux vendors, a Linux cluster is not a high performance computer, said Dr. Paul Terry, CTO of Cray Canada. "At best, clusters are a loose collection of unmanaged, individual, microprocessor-based computers."
Although this statement reeks of FUD, he's right about one thing: a cluster is not an HPC... that's why its called a cluster. But to say that a cluster is 'unmanaged' is one hell of a stretch IMO. All in all, he's just arguing semantics: nothing to see here, put down your flamethrowers, move along folks.
Since this is slashdot, I'll add that the rest of the article is full of choice quotes all of which point squarely at basic FUD + marketing spin for their new cluster-cost-like product.
It seems to me that Cray is just plain bitter that Linux (through all the cluster solution providers) has managed to steal Cray's thunder at a mere fraction of the cost. Cray's probably even more bitter that folks are willing to sacrifice performance (at least from Cray's perspective) just to save a buck.
Okay, this is Cray we're talking about here: people are saving millions of bucks all over the place by using clusters instead of big expensive machines.
And guess who wants 'their' slice of the pie back.
There are certain types of computing which simply cannot be done with microprocessor based platforms including clustering. One of these calculation types is vector processing. A Cray supercomputer is a vector processing based unit. When comparing a cluster of PC systems being used to calculate what a single Cray is designed to calculate, the Cray CTO is perfectly correct in his statement.
I'm seeing alot of single threaded versus multi-threaded arguments.
That's great and all, but for a single threaded application a cray isn't even going to smash your modern top of the line home pc by too terribly much.
crays are massive smp systems, they need a multi-threaded app to take advantage just as much as a cluster does. The difference is in the bus speed. A cray has a much faster bus, and with equivelent processing and memory it will excel with a number of small quickly terminated threads, whereas a cluster will as well or better with larger more processor consuming threads.
Why would a cluster ever do better? Simple, although a cluster has a drastically slower bus, there is memory local to the processor in question so there is much less congestion on the bus, and since if your shelling out for a cluster you will be switching rather than hub style whatever you do there will be almost without collisions and bus contention. Each node has it's own ram so there isn't much of an issue with contention for the bus and much greater memory throughput.
So like I said, it's all about how fast threads spawn and terminate, because if your rapid firing threads then you will doing alot of communicating between nodes over the slow bus (network), if your sending good sized chunks of data do something and keeping your nodes busy they will spend more time working and less time communicating results and your cluster will tromp all over that cray.
At what price point does the Cray XD1 come in? While huge clusters are (supposedly) cheap individual computers -- I would argue that G5s are not inherantly cheap -- how many G5s that make up the Virginia Tech cluster would you have to get to before you've paid for a Cray XD1?
I mention this because the article implies that Cray is planning on selling the XD1s at a price point cheaper than equivelant clusters. If they succeed at making the XD1 cheap enough, then it may be more cost effective to [[ effectively, cluster ]] a couple of these Crays, with less power consumption, heat dissipation and plain old real-estate.
It seems to me that TCO would be cheaper for the Cray, especially considering that the best clusters expect 5% of the member computers to be broken at any given time.
So, does anybody have Cray XD1 pricing? That, seems to me, to be the only way to rationally decide on the 'better' solution.
Kinetic stupidity has a new brand leader: Allen Zadr.
And it's worth noting, for the uninformed, that the reason Slash puts in the spaces is that there used to be a problem with page-widening fucks screwing up the comments sections with deliberately wide strings.
It's not a 'bug' in the slashcode.
resigned
Every other machine in the top 10 is built from standard processors. The old DEC Alpha, PowerPCs, and IA-32 predominate, with a few Itanium machines.
Because supercomputers today have several thousand processors, they can't even be big shared-memory multiprocessors. Speed of light lag in the interconnects would slow everything down. It just takes too long for the signals to make it across the room.
So all supercomputers today are clusters of one kind or another, fast machines with slower interconnects between them. The hardware architecture revolves around interconnect schemes. The software architecture revolves around working around the limitations of the interconnect schemes. Tightly coupled problems don't map well to such machines.
Bear in mind that we're talking about clusters of uniform machines located near each other with gigabit or better interconnects. We're not talking about "clusters" consisting of spare-time programs out at the end of Internet connections. Those are useful only for problems with almost no coupling between parts. Such problems are usually low hit rate search problems, like cryptanalysis, SETI@HOME, and such.
Yes, there's the Cray X1, the last of the liquid-cooled monsters, but it looks like the only customers who bought one were Government agencies with old Cray machines.
Most readers have the right idea - you don't listen to a competitor's opinion when judging whether something is viable or not. It is very easy to twist the words to be "true" while misleading.
A cluster isn't a supercomputer, by definition, but for many jobs can be equal or better. In other words: Those 2 oxen cost more, consume more resources, are only useful for the one job (pulling a plow) and only benefit a single owner. Those 1024 chickens cost less, consume less resource, are useful for many jobs besides the one (including laying eggs) and benefit their many owners.
I was taking one day at a time, but then several days got together and ambushed me. (from a Rhymes with Orange comic)
I asked this earlier in the thread: Provably non-Parallelizable?
Allow me to ask it again: What's the state of the art of proofs of parallelizability [and non-parallelizability]?
Is there a standard list of problems that have been proven to be non-parallelizable? Are there any problems that have been proved to be parallelizable, but for which no parallelizing algorithm has yet been discovered? Is there anything analogous to the NP-completeness conjecture in this field?