NVIDIA's Fermi: Architected for Tesla, 3 Billion Transistors in 2010
by Anand Lal Shimpi on September 30, 2009 12:00 AM EST- Posted in
- GPUs
ECC Support
AMD's Radeon HD 5870 can detect errors on the memory bus, but it can't correct them. The register file, L1 cache, L2 cache and DRAM all have full ECC support in Fermi. This is one of those Tesla-specific features.
Many Tesla customers won't even talk to NVIDIA about moving their algorithms to GPUs unless NVIDIA can deliver ECC support. The scale of their installations is so large that ECC is absolutely necessary (or at least perceived to be).
Unified 64-bit Memory Addressing
In previous architectures there was a different load instruction depending on the type of memory: local (per thread), shared (per group of threads) or global (per kernel). This created issues with pointers and generally made a mess that programmers had to clean up.
Fermi unifies the address space so that there's only one instruction and the address of the memory is what determines where it's stored. The lowest bits are for local memory, the next set is for shared and then the remainder of the address space is global.
The unified address space is apparently necessary to enable C++ support for NVIDIA GPUs, which Fermi is designed to do.
The other big change to memory addressability is in the size of the address space. G80 and GT200 had a 32-bit address space, but next year NVIDIA expects to see Tesla boards with over 4GB of GDDR5 on board. Fermi now supports 64-bit addresses but the chip can physically address 40-bits of memory, or 1TB. That should be enough for now.
Both the unified address space and 64-bit addressing are almost exclusively for the compute space at this point. Consumer graphics cards won't need more than 4GB of memory for at least another couple of years. These changes were painful for NVIDIA to implement, and ultimately contributed to Fermi's delay, but necessary in NVIDIA's eyes.
New ISA Changes Enable DX11, OpenCL and C++, Visual Studio Support
Now this is cool. NVIDIA is announcing Nexus (no, not the thing from Star Trek Generations) a visual studio plugin that enables hardware debugging for CUDA code in visual studio. You can treat the GPU like a CPU, step into functions, look at the state of the GPU all in visual studio with Nexus. This is a huge step forward for CUDA developers.
Nexus running in Visual Studio on a CUDA GPU
Simply enabling DX11 support is a big enough change for a GPU - AMD had to go through that with RV870. Fermi implements a wide set of changes to its ISA, primarily designed at enabling C++ support. Virtual functions, new/delete, try/catch are all parts of C++ and enabled on Fermi.
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AlexWade - Wednesday, September 30, 2009 - link
How long have you been working for NVidia?taltamir - Thursday, October 1, 2009 - link
don't insult nvidia by insinuating that this zealot is their employeedzoni2k2 - Wednesday, September 30, 2009 - link
What the heck is wrong with you SiliconDoc?Since when is memory bandwidth main indicator of performance?!
For all I care Fermis memory bandwidth can be 999GB/s but what good is that if it's not used?
SiliconDoc - Friday, October 2, 2009 - link
I'm sure "it won't be used" because for the very first time "nvidia will make sure it "won't be used" becuase "they designed it that way ! " LOL--
You people are absolutely PATHETIC.
Now the greater Nvidia bandwith doesn't matter, because you don't care if it's 999, because... nvidia failed on design, and "it won't be used!"
ROFLMAO
Honestly, if you people heard yourselves...
I am really disappointed that the bias here is so much worse than even I had known, not to mention the utter lack of intellect so often displayed.
What a shame.
PorscheRacer - Wednesday, September 30, 2009 - link
Exactly! R600 had huge bandwidth but couldn't effectively use it; for the msot part. Is this huge bandwdth the GF300 has only able to be used in cGPU, or is it able to be used in games, too? We won't know till the card is actually reviewed a long while from now.SiliconDoc - Wednesday, September 30, 2009 - link
What a joke. The current GT200 responds in all flavors quite well to memory clock / hence bandwith increases.You know that, you have been around long enough.
It's great seeing the reds scream it doesn't matter when ati loses a category. (no actually it isn't great, it's quite sickening)
SiliconDoc - Wednesday, September 30, 2009 - link
Yes of course bandwith does not really matter when ati loses, got it red rooster. When nvidia is SO FAR AHEAD in it, it's better to say "it's not double"...LOL---
WHAT IS WRONG WITH YOU PEOPLE AND THE AUTHOR IS THE REAL QUESTION!
--
What is wrong with you ? Why don't you want to know when it's nvidia, when it's nvidia a direct comparison to ati's card is FORBIDDEN !
That's what the author did !
It was " a very adept DECEPTION" !
---
Just pointing out how you get snowballed and haven't a clue.
Rumors also speculated 4,000 data rate ddr5
4000x384/8 - 192 bandwith, still planty more than 153 ati.
CLEARLY though "not double 141" (nvidia's former number also conveniently NOT MEWNTIONED being so close to 153/5870 is EMBARRASSING) - is 282...
--
So anand knows it's 240, not quite double 141, short of 282.
DigitalFreak - Wednesday, September 30, 2009 - link
Looks like SnakeOil has another alias!therealnickdanger - Wednesday, September 30, 2009 - link
Agreed. That was refreshing!mapesdhs - Wednesday, September 30, 2009 - link
Blimey, I didn't know Ujesh could utter such things. :D When I knew
him in 1998 he was much more offical/polite-sounding (he was Product
Manager for the O2 workstation at SGI; I was using a loaner O2 from
SGI to hunt for OS/app bugs - Ujesh was my main contact for feedback).
The poster who talked about availability has a strong point. My brother
has asked me to build him a new system next week. Looks like it'll be
an Athlon II X4 620, 4GB RAM, 5850, better CPU cooler, with either an
AM3 mbd and DDR3 RAM or AM2+ mbd and DDR2 RAM (not sure yet). By heck
he's going to see one hell of a speed boost; his current system is a
single-core Athlon64 2.64GHz, 2GB DDR400, X1950Pro AGP 8X. :D My own
6000+ 8800GT will seem slow by comparison... :|
Ian.