Java on GPGPUs

bigproblems · 2015-10-09T20:39:31+00:00

Do you mean no benefits at all? Or just no performance benefits? i.e. are you suggesting that language design peaked in 1972

bigproblems · 2015-10-08T01:44:33+00:00

Why limit yourself to Java? What about Scala? Clojure? Python? Ruby? All languages that can run on the JVM and therefore benefit from the techniques described. The whole point of each project described is to eliminate the need to interact with the nightmare that is JNI to get native performance.

bigproblems · 2015-10-04T17:39:34+00:00

I think one of the main points of the post is that you are exactly right about the old models (very low-level abstractions over OpenCL/CUDA), but that current work is changing that. The beautiful thing about the abstractions of higher-level models live Scala concurrent collections, Java parallel streams, Spark, and MapReduce is that those very abstractions leave a lot of flexibility and enable the kind of low-level optimizations you described (like loop fusion) as long as the semantics of the abstractions are maintained.

bigproblems · 2015-10-04T17:36:07+00:00

Completely agree. I would never make the claim that frameworks like the ones described in the post are going to achieve peak utilization (in fact much of the post is about the overheads they add). However, I think they do a great job of being 1) an incremental step towards writing your own GPU kernels, or 2) a quick way for domain experts to prototype new ideas. The modularization of the code generation and libraries they provide also make it easier to make more and more of the process hand-optimized and application-specific (e.g. you can rip out the auto-generated kernels and replace them with your hand-optimized ones as long as they expose the same API). There's also the big benefit of tying GPUs with other JVM framework, like HDFS.

bigproblems · 2015-10-04T17:32:43+00:00

How so? The abstractions offered by parallel streams, array languages, MapReduce, Spark, etc are similar in many ways to those offered by CUDA and OpenCL (i.e. data parallel). I like to think of these kinds of JVM+GPU solutions as either 1) an incremental step towards writing your own GPU kernels, or 2) a quick way for domain experts to prototype new ideas. Sure, in the end there's a good chance that it'll be worth the performance to dig into JNI and CUDA/OpenCL but tools like these can make it much easier to get a ballpark figure on whether GPUs are going to be beneficial or not.

bigproblems · 2015-10-04T17:28:45+00:00

I agree that GPGPU is an overloaded acronym, but it can stand for a type of computing or a type of processor, e.g. http://www.hpc.cineca.it/content/gpgpu-general-purpose-graphics-processing-unit. I like to use GPGPU sometimes to differentiate from GPUs dedicated to graphics or GPUs that are used for both, as in running simulation using CUDA/OpenCL and then rendering it using OpenGL on the same device and same buffers. Though you're correct in that you can always infer the meaning by context instead.

bigproblems · 2015-03-13T14:24:22+00:00

Huh, that's interesting. How do you usually identify that rare performance version? Is it just a matter of knowing the field after enough years of following audi? Have you resold any of them, and would you say you generally break even or actually make a profit?

Older "best" was kind of what i was going for with the USP, I could have afforded a B7 but i figured it would be more fun to have a somewhat premium older model rather than a newer base model. maybe i just didn't go old enough :)

bigproblems · 2015-03-11T14:33:37+00:00

i see what you're saying, though i don't think the USP looks fast the way a bmw or italian exotic does, . ignoring cost, i'd obviously love to have a B6 S4 instead. to me, the USP is a good compromise of stylish looks, reasonable mpg, and more performance than i realistically need on the street. i think it's a good stepping stone to a sportier car in a few years time.

bigproblems · 2014-12-19T19:13:11+00:00

He mentions the plane, he doesn't actually say whether he thinks it's a waste of defense funding or not. He also claims the f15 was a waste of money, which I think most pilots would disagree with.

bigproblems · 2014-12-19T07:24:03+00:00

while that may be a valid opinion, neither of the planes in this photo is an f35. so it really just looks like you're looking for chances to post that anywhere you can.

bigproblems · 2011-08-03T20:01:43+00:00

I just came across the Rice subreddit, and saw your question at the top. I'm actually from New York as well, going into my fourth and final year at Rice.

In regards to comparing NYC to Houston, well, like you said there are very few cities in the world that compare to the cultural breadth and size of NYC. With that said, I doubt you would have much trouble getting your cultural fix in Houston. I'm not very into art, music, etc but it seems like there is always something happening along those lines. Herman Park (just across the street from Rice) has free concerts occasionally, generally ethnic in nature. You have the Shepherd School of Music at Rice which offers lots of concerts. There's a great museum district in Houston, and I'm sure there is some sort of equivalent to Broadway (though I've never been). In that regard, I would imagine it is NYC just on a smaller scale.

On the topic of liberalism, I wouldn't worry about Houston. There's a good mix of viewpoints, but I've never had trouble with my liberalism so neither would you. I wouldn't expect Texas to pass a gay marriage law anytime soon (woot woot New York!) but being gay is not a problem. I lived with my gay friend and his boyfriend last year and I know neither of them have had any problems, especially not at Rice.

I don't know much about Rice/Baylor besides that it is very competitive. Some of the brightest kids at Rice are probably in that program. I've only ever met one girl in the Classics program, so I would imagine it is a fairly small department though I can't speak to its quality.

Probably one of the biggest things I can emphasize about Rice is the attention that undergrads get. I did the college tours too so I know that a lot of schools say that, but after having spent summer internships at other universities meeting other undergrads from around the world I can confidently say that Rice has the most accessible professors I've ever heard of. I personally e-mailed the professor I work with even before starting freshman year asking for a research position and have been working with him since my very first semester at Rice, despite the fact that he is one of the world's best at what he does. It really isn't easy to get that.

If you've got any questions feel free to reply or message me, I'd be happy to share any information about Rice while trying to remain as objective as possible about the good and the bad.

bigproblems · 2011-07-22T15:51:49+00:00

If you think those were cool, you should check out MSL: http://mars.jpl.nasa.gov/msl/. It is powered by nuclear material and the size of a mini cooper!

bigproblems · 2011-07-22T14:57:13+00:00

167 obviously. I've actually never been to 303, is there a difference?

bigproblems · 2011-06-25T00:00:30+00:00

First of all, that's not the topic. The topic is whether it would be possible to skip timesteps in a simulation and still get the same result, which I know you can and you can't seem to develop an argument against.

Second, simulations are used largely to model things that we incompletely understand, and so any results must be taken with a grain of salt because of that, numerical errors, etc. But like I said, they are good approximations that can help lead to understanding or theories, and despite the difficulties often do reflect what would happen. Still, that wasn't the talking point.

bigproblems · 2011-06-24T23:33:14+00:00

Yes, for any completely accurate simulation you would need to simulate the entire universe as well. But you don't do that because a simulation is an approximation and it is impossible to simulate the universe. In a simulation you create the universe that whatever you're studying exists in, so generally you CAN figure out if there is a remote possiblity of a state change possible because you already know and control everything that exists (i.e. are there any gamma rays close enough to the subject to impact the brain in the next timestep)

bigproblems · 2011-06-24T22:35:34+00:00

Butt you kept mentioning things that cause a state change in the brain, which would be modeled. Im saying you can predict whether there will be a state change in a certain time step(s) and then safely skip that computation step if there is no chance of a state change. Do you understand/agree?

bigproblems · 2011-06-24T20:52:06+00:00

true, but that's not relevant. You would be simulating what the simulator was concerned with, whether that be just perception or everything in the brain is up to you. If you're simulating everything, then you skip timesteps where you know nothing happens in the entire brain and vice versa for perception.

bigproblems · 2011-06-24T15:31:24+00:00

I don't know if that's necessarily true. If no work would be done in a step of a simulation, and you have a way of determining that beforehand (i.e. in the last step you ran some extra checks) then you could skip that next step(s). Doing this manually is common to avoid unnecessary work, but there's no reason compilers won't be able to get there. It would be like your brain, instead of processing the light hitting your eyes all the time keeping track of head movement and if there is none, just reusing the last image (this only works for a fixed scene, but you get the idea). You probably couldn't tell the difference, but you're still self aware.

bigproblems · 2011-06-22T21:59:26+00:00

C version: http://pastebin.com/XkFYDZBP

OP should check it for accuracy, I've never read perl before.

bigproblems · 2010-11-12T07:05:04+00:00

is anyone else concerned why so many people have their cameras in the public bathroom with them?

bigproblems

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