I remember several times it was mentioned here during forum discussions that AMD needs to change their SP's/core architecture as it is not efficient enough. I always thought that the way AMD did things was fine since they give you almost 100% of the performance with 60% of the silicon.
One of the arguements that was brought up over and over is how the GT200 GPU's are so much larger due to the fact that they are also aimed to be used as GPGPU processors in addition to being standard GPU's, so there is a lot of extra silicon dedicated to those GPGPU functions.
I had asked in a few threads to be shown what exactly was used for GPGPU functionality in the GT200, but never really got an answer.
With the upcoming launch of the Fermi/GT300, some details about the new chip are starting to come forward. One thing we know is that with this new GPU Nvidia is truely trying to create and make a move into the GPGPU world in earnest. If we take a look at this link (tablet in the middle especially), we see a lot of changes from the GT200 architecture to Fermi that I understand are there for GPGPU functionality. But when looking at the G80 vs. GT200, there aren't many changes at all.
I know in the GT200 days Nvidia liked to talk up GPGPU ability and promote it, but I hadn't seen what they did at the silicon level to tweak the architecture for it to be truely aimed at GPGPU more so than the G80/G92 GPU's before it. It seems like it was just talked about more and a push in that direction was made at that time more so than the silicon envisioned and built with exceling at those GPGPU functions in mind. Basically they marketed it like the GT200 was built with that functionality in mind, but to me it seems more like they just created apps to work with the GPU's they had.
So I guess this brings us to Fermi (and the RV870). What about Fermi makes us think that it should be faster then a 5870 by a larger percentage then a GTX285 is faster than a 4890 (other than then the fact that AMD more or less doubled everything, Nvidia slightly more than doubled SP's by going 240 -> 512). Also, if we look at AMD's 5870 architecture (here) and (here) you'll see that AMD also tweaked their architecture in a few areas.
From the PC Perspective article, Nvidia has gone from 16KB L1 cache/shared memory to a 'configurable' 48KB. From the AT article AMD has kept the L1 texture cache at the same 16KB as the prior gen, but increased the speed (1TB/sec) as well as added a seperate 8KB L1 cache for the SIMD's and doubling the local data share to 32KB (from the prior gen). From PC Perspective, Nvidia is adding a seperate 768KB of L2 cache, from the AT article, AMD has 4 seperate L2 caches that they are doubling in size to 128KB from the prior gen.
I won't lie and pretend like I know how all of this will work differently in the different architectures, but again it looks like Nvidia will talk up GPGPU, but I'm not sure if AMD is really far behind them on a silicon level and they just need to push the software, or if Nvidia really is better optimized for GPGPU. Also, I'm not convinced that Nvidia had all of that silicon for GPGPU functions with the GT200, I think it's quite an accomplishment that AMD was able to give similar performance (though with more clock speed) with so much less silicon.
I figured at the very least this would at least make for some good discussion if anyone wants to jump in and tell me why I'm wrong... or better yet why I'm right.
Cliffs:
AMD GPU's are smaller than Nvidia GPU's but performance is similar.
Are Nvidia GPU's really more aimed towards GPGPU?
One of the arguements that was brought up over and over is how the GT200 GPU's are so much larger due to the fact that they are also aimed to be used as GPGPU processors in addition to being standard GPU's, so there is a lot of extra silicon dedicated to those GPGPU functions.
I had asked in a few threads to be shown what exactly was used for GPGPU functionality in the GT200, but never really got an answer.
With the upcoming launch of the Fermi/GT300, some details about the new chip are starting to come forward. One thing we know is that with this new GPU Nvidia is truely trying to create and make a move into the GPGPU world in earnest. If we take a look at this link (tablet in the middle especially), we see a lot of changes from the GT200 architecture to Fermi that I understand are there for GPGPU functionality. But when looking at the G80 vs. GT200, there aren't many changes at all.
I know in the GT200 days Nvidia liked to talk up GPGPU ability and promote it, but I hadn't seen what they did at the silicon level to tweak the architecture for it to be truely aimed at GPGPU more so than the G80/G92 GPU's before it. It seems like it was just talked about more and a push in that direction was made at that time more so than the silicon envisioned and built with exceling at those GPGPU functions in mind. Basically they marketed it like the GT200 was built with that functionality in mind, but to me it seems more like they just created apps to work with the GPU's they had.
So I guess this brings us to Fermi (and the RV870). What about Fermi makes us think that it should be faster then a 5870 by a larger percentage then a GTX285 is faster than a 4890 (other than then the fact that AMD more or less doubled everything, Nvidia slightly more than doubled SP's by going 240 -> 512). Also, if we look at AMD's 5870 architecture (here) and (here) you'll see that AMD also tweaked their architecture in a few areas.
From the PC Perspective article, Nvidia has gone from 16KB L1 cache/shared memory to a 'configurable' 48KB. From the AT article AMD has kept the L1 texture cache at the same 16KB as the prior gen, but increased the speed (1TB/sec) as well as added a seperate 8KB L1 cache for the SIMD's and doubling the local data share to 32KB (from the prior gen). From PC Perspective, Nvidia is adding a seperate 768KB of L2 cache, from the AT article, AMD has 4 seperate L2 caches that they are doubling in size to 128KB from the prior gen.
I won't lie and pretend like I know how all of this will work differently in the different architectures, but again it looks like Nvidia will talk up GPGPU, but I'm not sure if AMD is really far behind them on a silicon level and they just need to push the software, or if Nvidia really is better optimized for GPGPU. Also, I'm not convinced that Nvidia had all of that silicon for GPGPU functions with the GT200, I think it's quite an accomplishment that AMD was able to give similar performance (though with more clock speed) with so much less silicon.
I figured at the very least this would at least make for some good discussion if anyone wants to jump in and tell me why I'm wrong... or better yet why I'm right.
Cliffs:
AMD GPU's are smaller than Nvidia GPU's but performance is similar.
Are Nvidia GPU's really more aimed towards GPGPU?
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