The RV870 Story: AMD Showing up to the Fight
by Anand Lal Shimpi on February 14, 2010 12:00 AM EST- Posted in
- GPUs
Carrell Loses His Baby: Say Goodbye to Sideport
Sitting at dinner with Eric Demers and Carrell Killebrew is honestly one of the best experiences I’ve ever had working with ATI. Before he got huge and subsequently left, I used to have annual dinners with Pat Gelsinger at Intel. They were amazing. To get to sit at the same table as someone as talented and passionate as a Gelsinger, Demers or Killebrew is one of the most fortunate and cherished parts of my job.
Eric was telling me about how they trimmed down 870 from over 400mm2 down to 334mm2 and how wonderful the end product was. I stopped him and asked for more detail here. I wanted an example of a feature that they had to throw out but they really wanted to keep in. Manufacturers rarely tell you what they threw out, marketing likes to focus on what’s in the chip and make everything sound like a well calculated move. Thankfully, marketing wasn’t allowed to speak at my dinner.
Eric turned to Carrell and said: “i know one feature we could talk about.”
“Sideport”.
Carrell responded, “OH MY GOD, that’s totally not fair.” (note that Carrell does not sound like a teenage girl, imagine that phrase just spoken more engineer-y).
When ATI first talked about the Radeon HD 4870 X2 they told us about a feature called Sideport. It was a port off each RV770 GPU that could be used for GPU-to-GPU communication.
Sideport as it was intended to be used
The whole point of doing CrossFire in alternate frame rendering mode (AFR) is that the chips never have to talk. The minute you have to start synchronizing them, you kill performance. Sideport was supposed to alleviate that.
Unfortunately, due to power reasons, Sideport was never used on the 4870 X2. ATI’s reference design had it disabled and all vendors followed suit.
Sideport was Carrell Killebrew’s favorite feature, and he had to give it up.
In early 2008 ATI realized they had to cut this chip down from 20 - 22mm on a side to 18mm, everyone had to give up something. Carrell was the big advocate for making 870 smaller, he couldn’t be a hypocrite and not give anything up.
A bunch of my conversation with Carrell at this point had to go off the record. Sideport would have been useful in RV870, but it’s unfortunately not there. Although he did tell me not to be surprised if I saw Sideport again at some point. Carrell doesn’t give up easily.
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Stas - Sunday, February 14, 2010 - link
Awesome. Thanks!Adul - Sunday, February 14, 2010 - link
Really helps pass the time at work today. :) Keep it up.Btw when can we expect to see the new site launch?
aapocketz - Sunday, February 14, 2010 - link
[quote]I was convinced that ATI had embraced a new, refocused approach to GPU design, only to learn that they nearly threw out all of the learnings with the RV870. [/quote]It sounds like they have had some successes trying different techniques, but without stability in their production process it is hard to repeat success. I understand that they require constant innovation to stay competitive, but throwing out whole processes seems chaotic to me. I would like them to refine and improve successful processes rather than toss everything every time a new business guru is in charge.
Also half of their effort was all about openness and collaboration. The opening up of the PRS document so that "everyone was involved in the process" seems to clash with the hyper-secret groups where "AMD has since incorporated much of Carrell’s brand of information compartmentalization into how it handled other upcoming features." This seems like a recipe for disaster to me. Which is it, broad openness, collaboration and consesus; or secret teams that have no idea what the other teams are doing?
SuperGee - Sunday, February 14, 2010 - link
The story told us that they didn't know it will become a succes because these desision where made before RV770 release. So doing the high risk choice again. Wasn't a nobrainer. But a risky choice. We know that it turn out good now.mckirkus - Sunday, February 14, 2010 - link
It's kind of funny that you're not yet running one of these companies yet Anand.One of the reasons I check this site on a daily basis is because you also seem to also get the business side of the equation. It's downright refreshing to see someone bridging that gap. You pretty much saved the Vertex from self destruction. I'd like to see what interesting things you could build us if you put your mind to it.
deputc26 - Sunday, February 14, 2010 - link
Articles like these are what differentiate AnandTech from all the other sites out there. AnandTech goes from being one of the best review sites out there to something special.Beyond excellent, thanks Anand.
rickyv - Sunday, February 14, 2010 - link
As a loyal follower of your website for the past 15 years, I also felt that I just had to register and compliment you on an excellent article.With the rapid advancement of technology, it is very easy just to get caught up in the PR and marketing hype or focus only on the numbers game. We often lose sight of the fact that it is teams of dedicated people who make this possible. You have always had the ability to bring out the "human" side to this. I have not seen this on any other site nor in printed form (that is not an unashamedly PR marketing exercise).
Thanks for staying true to your roots by giving honest opinions of the technology that you review. The latest releases are not necessarily always the greatest (as much as the marketing departments would like us to believe :-) )
krish123 - Sunday, February 14, 2010 - link
After i read the article, I found that "Engine is running well and firing on all the cylinders", It can create better products in the future, I can trust and buy ATI products, hope they deliver better products in the future for my upgrade."Kudos to Anand for the excellent article".
By the way graphics card is a product, not just hardware, it has to work in tandem with the software, its better ATI put some more effort on the driver/software side and fix all the issues.
Krish
smartalec - Sunday, February 14, 2010 - link
"When companies like AMD and NVIDIA do a product the engineers don't know all of the answers, and the knowledge they do have isn't binary - it's probability, it's weight, it's guesses. Sometimes they guess right, and sometimes they guess very wrong. The best they can do is to all weigh in with their individual experiences and together come up with the best group of guesses to implement."I'm afraid this is how all engineering works. Project managers think that engineers can predict the future. That we know exactly how much time it'll take, and how much risk a given feature will bring.
We don't. There's a lot of educated guesses. Sometimes we're pleasantly surprised that what we thought was a tough problem wasn't. Sometimes we're the bearer of bad news-- something we assumed would be trivial wasn't.
My most frustrating issues aren't technical at all. I ask for 2000 hours, and are given 1000. Or are given 2 engineers instead of 3, and told-- figure out a way to get it done anyway, without impacting schedule.
Great article Anand.
mckirkus - Sunday, February 14, 2010 - link
Any decent project manager (I do software) reviews the risks up front with the engineers before building the project plan / timeline.The fact that most project managers don't really understand the products they manage is the rule not the exception. The problem is that great engineers don't always make great PMs. Having a good tech lead helps.