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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Pirks - Monday, October 5, 2009 - link
No, Jarred, they are advancing towards 2560x1600 on every PC gamer's desk. Since they move towards that (used to be 800x600 everywhere, now it's more like 1280x1024 everywhere, in couple of years it'll be 1680x1050 everywhere and so on) they cannot be described as stagnant, hence your statement is BS, Jarred.mejobloggs - Tuesday, October 6, 2009 - link
I think I'll agree with Jared on this oneLCD tech isn't advancing enough to get decent high quality large screens at a decent price. 22" seems about the sweet spot which is usually 1680x1050
Pirks - Wednesday, October 7, 2009 - link
This sweet spot used to be 19" 1280x1024 a while ago, with 17" 1024x768 before that. In a couple of years sweet spot will move to 24" 1920x1200, and so on. Hence monitor resolution does progress, it does NOT stagnate, and you do listen to Jarred's fairy tales too much :PJarredWalton - Friday, October 9, 2009 - link
What we have here is a failure to communicate. My point, which you are ignoring, is that maximum resolutions are "stagnating" in the sense that they are remaining static. It's not "BS" or a "fairy tale", unless you can provide detail that shows otherwise. I purchased a 24" LCD with a native 1920x1200 resolution six years ago, and then got a 30" 2560x1600 LCD two years later. Outside of ultra-expensive solutions, nothing is higher than 2560x1600 right now, is it?1280x1024 was mainstream from about 7-11 years ago, and 1024x768 hasn't been the norm since around 1995 (unless you bought a crappy 14/15" LCD). We have not had a serious move to anything higher than 1920x1080 in the mainstream for a while now, but even then 1080p (or 1200p really) has been available for well over 15 years if you count the non-widescreen 1600x1200. I was running 1600x1200 back in 1995 on my 75 pound 21" CRT, for instance, and I know people that were using it in the early 90s. 2048x1536 and 2560x1600 are basically the next bump up from 1600x1200 and 1920x1200, and that's where we've stopped.
Now, Anand seems to want even higher resolutions; personally, I'd be happier if we first found a way to make those resolutions work well for every application (i.e. DPI that extends to everything, not just text). Vista was supposed to make that a lot better than XP, but really it's still a crap shoot. Some apps work well if you set your DPI to 120 instead of the default 96; others don't change at all.
Pirks - Friday, October 9, 2009 - link
I agree that maximum resolution has stagnated at 2560x1600, my point was that the average resolution of PC gamers is still moving from pretty low 1280x1024 towards this holy grail of 2560x1600 and who knows how many years will pass until every PC gamer will have such "stagnated" resolution on his/her desk.So yeah, max resolution stagnated, but average resolution did not and will not.
I am as mad as hell - Friday, October 2, 2009 - link
Hi everyone,first off, I am not mad as hell! I just registered this acct after being an Anandtech reader for 10+ years. That's right. It's also my #1 tech website. I read several others, but this WAS always my favorite.
I don't know what happened here lately, but it's becoming more and more of a circus in here.
I am going to make a few points suggestions:
1) In the old days reviews were reviews, this days I there are a lot more PRE-views and picture shows and blog (chit chatting) entries.
2) In the old days a bunch of hardware was rounded up and compared to each other (mobos, memory, PSU's, etc..) I don't see that here much anymore. It's kind of worthless to me just to review one PSU or one motherboard at the time. Round em all up and then lets have a good ole fashioned shootout.
3) I miss the monthly buyer guides. What happened to them? I like to see CPU + Mobo + Mem + PSU combo recommendations in the MOST BANG FOR THE BUCKS categories (Something most people can afford to buy/build)
4) Time to moderate the comments section, but not censorship. My concern is not with f-words, but with trolls and comment abusers. I can't stand it. I remember the old days when then a famous site totally self-destruct, and at that time I think had maybe more readers than Anand, (hint: It had the English version of "Tiburon" as name as part of the domain name) when their forum went totally out of control because it was moderated.
5) Also, time to upgrade the comments software here at Anandtech. It needs a up/down ratings feature that even many newspaper websites offer these days.
shotage - Saturday, October 3, 2009 - link
I agree with the idea of a comments rating system (thumbs up or down). Its a democratic way of moderating. It also saves the need for those short replies when all you want to convey is that you agree or not.Maybe also an abuse button that people can click on should things get really out of control..?
Skiprudder - Friday, October 2, 2009 - link
The up/down idea is perfect for the site. Now why didn't I think of that! =)AnnonymousCoward - Friday, October 2, 2009 - link
I don't like commenter ratings, since they give unequal representation/visibility of comments, they affect your perception of a message before you read it, and it's one more thing to look at while skimming comments.Skiprudder - Friday, October 2, 2009 - link
I'm sorry, but I'm going to ask for a ban of SiliconDoc as well. One person has single-handedly taken over the reply section to this article. I was actually interested in reading what other folks thought of what I feel is a rather remarkable new direction that nvidia is taking in terms of gpu design and marketing, and instead there are literally 30 pages of a single person waging a shouting matching with the world.Right now there isn't free speech in this discussion because an individual is shouting everyone down. If the admins don't act, people are likely to stop using the reply section all together.