AMD's Radeon HD 5870: Bringing About the Next Generation Of GPUs
by Ryan Smith on September 23, 2009 9:00 AM EST- Posted in
- GPUs
A Quick Refresher on the RV770
As Cypress is a direct evolution of the RV770 design, before we talk about what’s new with Cypress we are going to go over a quick rehash of RV770’s internal workings. As it’s necessary to understand how RV770 was built to understand what Cypress changes, if you’re completely unfamiliar with RV770, please take a look at our expanded discussion of RV770 from last year. For the rest of you, let’s get started.
At the center of the RV770 is the Stream Processing Unit (SPU), a single arithmetic logic unit. The RV770 has 800 of these, and they are packaged together in groups of 5 and are what we call a Streaming Processor (SP). A SP contains a register file, a branch predictor, and the aforementioned 5 SPUs, with the 5th SPU being a more complex unit capable of transcendental functions along with the base functions of an ALU. The SP is the smallest unit that can do individual work; every SPU in an SP must execute the same instruction.
For every 16 SPs, AMD groups them together with texture units, L1 cache, shared memory, and controlling logic. This combined block is what AMD calls a SIMD, and RV770 has 10 of them. These 10 SIMDs form the core computational power of the RV770, and in the chip work with various specialized units such as ROPs, rasterizers, L2 cache, and tesselators to form a complete chip.
To utilize the computational power of the hardware, instruction threads are issued to the SPs. These threads are grouped into wavefronts, where there are 64 threads per wavefront. To maximize the utilization of the GPU, threads need to be organized so that they can feed all 5 SPUs in a SP an instruction every clock cycle. Doing this requires extracting instruction level parallelism (ILP) out of programs being passed to the GPU, which is difficult task of AMD’s compiler.
If SPUs go unused, then the performance of the chip suffers due to underutilization. This design gives AMD a great deal of theoretical computational power, but it is always a challenge to fully exploit it.
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pinguin - Monday, September 28, 2009 - link
It IS a hard launch as obviously a few cards are available. That consumers rip them off one's hand is another problem...Anyway I'll wait until the 5650: 4850 performance w/o PCIe connector + DX11: I'm coming! What else do I need to show off to my friends still staying with rebranded G92 chips!!
jabroni619 - Friday, September 25, 2009 - link
I guess it is, it was even better still when I decided to come home a bit early and UPS got there 2 hours sooner than they usually do. Playing through Crysis Warhead once more "The way it's meant to be played" on an ATI card though.Also included was a Dirt 2 code to be activated on steam, which I nearly threw out! Now I just have to wait for the game to be released.
camylarde - Thursday, September 24, 2009 - link
Lol. I was horrified, when i heard that my precious badminton racquet purchased on my friends address in england was "delivered" to the front door, waiting for him all day on the doorstep.if the card is gonna wait for you in a similar fashion, may i get to know where do you live to... erm... be there when you open the box and celebrate with you?
[/envy]
SiliconDoc - Wednesday, September 23, 2009 - link
I'm not certain how you saw any available then, looks from 3 different states didn't show that.Heck they weren't even active at 8 am, nor later than that. I guess you "got the only one" that wasn't Autonotify when arriving.
The0ne - Wednesday, September 23, 2009 - link
This is the last piece of hardware I've been waiting for before I build my i7 system. Now I think it's a ok time for enthusiast to start building again but on a cheaper budget with better performance :) no more of these 200-300 MB and stuff lolgwolfman - Wednesday, September 23, 2009 - link
I agree. Full bit-streaming support! Yeaz!blanarahul - Wednesday, December 21, 2011 - link
They should have given the option for 5870 to have triple DVI rather than single DVI + Dual DP. :(