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Modern GPU

nvlabs.github.io

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Re: Modern GPU

#21

Post by mjhoy »

gjm11 wrote: post #3

The title here, although it matches that of the linked page, conveys little information to anyone who doesn't already know what it's about. ("Modern GPU is code and commentary intended to promote new and productive ways of thinking about GPU computing. This project is a library, an algorithms book, a tutorial, and a best-practices guide.") Perhaps something like "Modern GPU: NVIDIA's guide to making effective use of…

The title at r/programming, by contrast, is

> New GPU computing ebook and library. Design methodologies, algorithms, tuning, the works.

Re: Modern GPU

#22

Post by hendzen »

jjoonathan wrote: post #20
quackerhacker wrote: post #9

Guide looks very well written, and I'm actually studying parallel programming right now...bookmarked. Side Note: Maybe this is Nvidia's way to promote sales, since AMD cards sold like crazy cause of the mining craze.

It's not reactionary: nvidia invested heavily in getting to market first and advertising to the HPC crowd and they have been reaping the rewards of a monopoly for a few years now. Their latest high-end cards are dramatically more expensive (vs AMD at the same raw computational power) while offering completely crippled GPGPU capabilities. I recall incredulity on IRC when people found that their new 6xx cards were a st…

Bitcoin miners flocked to AMD because the SHA-256 algorithm utilizes a 32-bit right rotate operation that AMD cards could execute in one clock cycle, while NVidia cards took ~3 cycles to do so.

At this point it doesn't really matter since GPU mining is obsolete.

Also, what's wrong with NVidia's GPGPU capabilities? The last time I had to write GPU code, I found that CUDA was much more mature - and much more pleasant to write than the equivalent OpenCL. Also, the benefits of being able to run OpenCL code on multiple compute platforms were being realized by CUDA with the development of a PTX to x86 compiler.

Re: Modern GPU

#23

Post by hdevalence »

hendzen wrote: post #22
jjoonathan wrote: post #20

Earlier quoted context omitted.

It's not reactionary: nvidia invested heavily in getting to market first and advertising to the HPC crowd and they have been reaping the rewards of a monopoly for a few years now. Their latest high-end cards are dramatically more expensive (vs AMD at the same raw computational power) while offering completely crippled GPGPU capabilities. I recall incredulity on IRC when people found that their new 6xx cards were a st…

Bitcoin miners flocked to AMD because the SHA-256 algorithm utilizes a 32-bit right rotate operation that AMD cards could execute in one clock cycle, while NVidia cards took ~3 cycles to do so. At this point it doesn't really matter since GPU mining is obsolete. Also, what's wrong with NVidia's GPGPU capabilities? The last time I had to write GPU code, I found that CUDA was much more mature - and much more pleasant t…

It's not just about right rotation, it's also about architectural differences: the AMD cards have more ALUs to work with.

https://en.bitcoin.it/wiki/Why_a_GPU_mines_faster_than_a_CPU...

Re: Modern GPU

#24

Post by vilya »

rdtsc wrote: post #5

So how do I use this with the new and modern Radeon HD7990 card? Hmm looks like there is no CUDA library for it... (flagging post for misleading title)

This is one way to run CUDA on your Radeon card: https://code.google.com/p/gpuocelot/

Although there's a note on that page saying that they're actively seeking developers for the AMD back-end, so I don't know how solid the support is.

Re: Modern GPU

#25

Post by jjoonathan »

hendzen wrote: post #22
jjoonathan wrote: post #20

Earlier quoted context omitted.

It's not reactionary: nvidia invested heavily in getting to market first and advertising to the HPC crowd and they have been reaping the rewards of a monopoly for a few years now. Their latest high-end cards are dramatically more expensive (vs AMD at the same raw computational power) while offering completely crippled GPGPU capabilities. I recall incredulity on IRC when people found that their new 6xx cards were a st…

Bitcoin miners flocked to AMD because the SHA-256 algorithm utilizes a 32-bit right rotate operation that AMD cards could execute in one clock cycle, while NVidia cards took ~3 cycles to do so. At this point it doesn't really matter since GPU mining is obsolete. Also, what's wrong with NVidia's GPGPU capabilities? The last time I had to write GPU code, I found that CUDA was much more mature - and much more pleasant t…

>Bitcoin miners flocked to AMD because the SHA-256 algorithm utilizes a 32-bit right rotate operation that AMD cards could execute in one clock cycle, while NVidia cards took ~3 cycles to do so.

That would have made the difference even larger, but even at 1:1 instruction timing AMD would have had a large price advantage so long as we're talking about the last 2 generations of cards or so. If the price/performance optimum lies further back than that, it may well have fallen at a point in time when AMD / NVidia were closer to price/performance parity.

To clarify, by "performance" I mean "performance for my needs" which means "double precision float performance."

> Also, what's wrong with NVidia's GPGPU capabilities?

The price per double-precision FLOP was off by a factor of four at the consumer level last time I went shopping and the number of DFLOPS available at the consumer level was capped lower. It seemed like a move to force penny-pinching CUDA-dependent academics to upgrade to teslas.

> The last time I had to write GPU code, I found that CUDA was much more mature - and much more pleasant to write than the equivalent OpenCL.

It still is, but the gap has closed for many use cases (including mine). I'm not saying that CUDA isn't/wasn't a reasonable choice, especially a few years back, just that we are now paying the hidden price that comes from allowing a monopoly to develop.

Re: Modern GPU

#26

Post by seanmcdirmid »

sliverstorm wrote: post #4
compilercreator wrote: post #2

Is it CUDA only or can we submit code written in OpenCL, DirectCompute or C++ AMP etc?

It looks like NVIDIA is hoping to highlight CUDA here. You can always try though.

To be honest, for the target audience of this book, CUDA is the only thing that matters right now. OpenCL and DirectCompute will possibly be significant in the future if AMD and Intel can catch up with NVIDIA in GPGPU performance.

Re: Modern GPU

#27

Post by seanbaxter »

It's my site. I didn't realize it was even posted here (I did post it at reddit).

To address some points:

The title of the site is kind of vague, agreed. I'm going to write an abstract for the index page to describe the gist of the design methodologies.

It's not part of an NVIDIA sales pitch, at all. I work in NVIDIA Research and have a lot of autonomy. I like doing programming patterns and algorithms research. At some point I had amassed a lot of stuff and thought it would be nice to share everything with the community.. no coordination with the marketing folks. My employer was nice enough to let me release it, but this is my project, not an official company one. This flexibility is one advantage of working in research.

I don't want to get dragged into a vendor or API debate. The MGPU project is about programming concepts. It wouldn't be hard for a developer to translate all the functions into another API--"hackability" is a goal that I talk about in the introduction. I chose CUDA because it's succinct (important for code readability) and its what I use on a daily basis.

Re: Modern GPU

#28

Post by Jach »

seanmcdirmid wrote: post #26
sliverstorm wrote: post #4

Earlier quoted context omitted.

It looks like NVIDIA is hoping to highlight CUDA here. You can always try though.

To be honest, for the target audience of this book, CUDA is the only thing that matters right now. OpenCL and DirectCompute will possibly be significant in the future if AMD and Intel can catch up with NVIDIA in GPGPU performance.

Here's a question you might be able to answer... what exactly do Nvidia cards do better than AMD cards? In the bitcoin and litecoin worlds, Nvidia is horribly outclassed for hash algorithms like sha-256 or scrypt. In the gaming world it's closer, but ATI's 79xx series still wins. (Especially when you consider in the cases a single 7970 isn't enough, which is true for several games, you can get 2 7970s for less than the price of a GTX Titan and win that way. Or a single 7990.) 32bit and 64bit floating point benchmarks favor AMD, the openCL Sala and Room benchmarks in Luxmark favor AMD... (Not exactly fair for that one since it's not CUDA, but the difference is enough that a performance boost from CUDA likely wouldn't close the gap.)

I suspect Nvidia's advantage is their proprietary software like PhysX and other software used in high-end computing or scientific-computing, and possibly they scale better (or simply there are Nvidia-supported solutions) when you want to add dozens of cards together. Is this the case? Because I don't see how one can claim AMD needs to "catch up" in performance if you're looking solely on a card-by-card basis.

Edit: Comparing http://clbenchmark.com/device-info.jsp?config=14470292&t... and http://clbenchmark.com/device-info.jsp?config=11905561&t... (easier comparison: http://clbenchmark.com/compare.jsp?config_0=11905561&con...), the only ones where Nvidia trounces are on Mergesort and memory usage of Gaussian blur; mergesort is mentioned in the submission. So what about the rest? And factoring in being able to buy two 7970s for the price of one Titan?

Re: Modern GPU

#29

Post by binarycrusader »

Jach wrote: post #28
seanmcdirmid wrote: post #26

Earlier quoted context omitted.

To be honest, for the target audience of this book, CUDA is the only thing that matters right now. OpenCL and DirectCompute will possibly be significant in the future if AMD and Intel can catch up with NVIDIA in GPGPU performance.

Here's a question you might be able to answer... what exactly do Nvidia cards do better than AMD cards? In the bitcoin and litecoin worlds, Nvidia is horribly outclassed for hash algorithms like sha-256 or scrypt. In the gaming world it's closer, but ATI's 79xx series still wins. (Especially when you consider in the cases a single 7970 isn't enough, which is true for several games, you can get 2 7970s for less than t…

Drivers, ISV certification and SDKs. Ask any user of AMD on Linux workstations what it's like. Then compare the experience of nVidia users.

AMD has the superior hardware in many ways, but their software just isn't quite there yet in my personal opinion.

Re: Modern GPU

#30

Post by baggers »

seanbaxter wrote: post #27

It's my site. I didn't realize it was even posted here (I did post it at reddit). To address some points: The title of the site is kind of vague, agreed. I'm going to write an abstract for the index page to describe the gist of the design methodologies. It's not part of an NVIDIA sales pitch, at all. I work in NVIDIA Research and have a lot of autonomy. I like doing programming patterns and algorithms research. At so…

Cheers for the great work, I'm really looking forward to working through this.
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