TPS Rep...err PRS Documents

At ATI there’s a document called the Product Requirement Specification, PRS for short. It was originally a big text document written in Microsoft Word.

The purpose of the document is to collect all of the features that have to go into the GPU being designed, and try to prioritize them. There are priority 1 features, which are must-haves in the document. Very few of these get canned. Priority 2, priority 3 and priority 4 features follow. The higher the number, the less likely it’ll make it into the final GPU.

When Carrell Killebrew first joined ATI, his boss at the time (Dave Orton) tasked him with changing this document. Orton asked Carrell to put together a PRS that doesn’t let marketing come up with excuses for failure. This document would be a laundry list of everything marketing wants in ATI’s next graphics chip. At the same time, the document wouldn’t let engineering do whatever it wanted to do. It would be a mix of what marketing wants and what engineering can do. Orton wanted this document to be enough of a balance that everyone, whether from marketing or engineering, would feel bought into when it’s done.

Carrell joined in 2003, but how ATI developed the PRS didn’t change until 2005.

The Best Way to Lose a Fight - How R5xx Changed ATI

In the 770 story I talked about how ATI’s R520 delay caused a ripple effect impacting everything in the pipeline, up to and including R600. It was during that same period (2005) that ATI fundamentally changed its design philosophy. ATI became very market schedule driven.


ATI's R520 Architecture. It was delayed.

The market has big bulges and you had better deliver at those bulges. Having product ready for the Q4 holiday season, or lining up with major DirectX or Windows releases, these are important bulges in the market. OEM notebook design cycles are also very important to align your products with. You have to deliver at these bulges. ATI’s Eric Demers (now the CTO of AMD's graphics group) put it best: if you don’t show up to the fight, by default, you lose. ATI was going to stop not showing up to the fight.

ATI’s switch to being more schedule driven meant that feature lists had to be kept under control. Which meant that Carrell had to do an incredible job drafting that PRS.

What resulted was the 80% rule. The items that made it onto the PRS were features that engineering felt had at least an 80% chance of working on time. Everyone was involved in this process. Every single senior engineer, everyone. Marketing and product managers got their opportunities to request what they wanted, but nothing got committed to without some engineer somewhere believing that the feature could most likely make it without slipping schedule.

This changed a lot of things.

First, it massively increased the confidence level of the engineering team. There’s this whole human nature aspect to everything in life, it comes with being human. Lose confidence and execution sucks, but if you are working towards a realistic set of goals then morale and confidence are both high. The side effect is that a passionate engineer will also work to try and beat those goals. Sly little bastards.

The second change is that features are more easily discarded. Having 200 features on one of these PRS documents isn’t unusual. Getting it down to about 80 is what ATI started doing after R5xx.

In the past ATI would always try to accommodate new features and customer requests. But the R5xx changes meant that if a feature was going to push the schedule back, it wasn’t making it in. Recently Intel changed its design policy, stating that any feature that was going into the chip had to increase performance by 2% for every 1% increase in power consumption. ATI’s philosophy stated that any feature going into the chip couldn’t slip schedule. Prior to the R5xx generation ATI wasn’t really doing this well; serious delays within this family changed all of that. It really clamped down on feature creep, something that’s much worse in hardware than in software (bigger chips aren’t fun to debug or pay for).

Index The Other Train - Building a Huge RV870
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  • devene - Sunday, February 14, 2010 - link

    Just like many others, I've been a long time reader and I just couldn't carry on without leaving a comment:

    This has been an article, just like the RV770 one. It may not reveal many facts but is tremendously insightful and inspiring. Thank you for bringing this deeply hidden information out to the public and to the "fans". Please do everything in your power to continue this trend.

    Once again, thank you Anand,
    devene
    Reply
  • medi01 - Sunday, February 14, 2010 - link

    Germans say "lange Rede kurzer Sinn". So many pointless sentences that do not tell anything even remotely interesting. Reply
  • TGressus - Sunday, February 14, 2010 - link

    Even the home team could not be sold on Eyefinity... Reply
  • William Gaatjes - Sunday, February 14, 2010 - link

    Fantastic article.

    "
    First, it massively increased the confidence level of the engineering team. There’s this whole human nature aspect to everything in life, it comes with being human. Lose confidence and execution sucks, but if you are working towards a realistic set of goals then morale and confidence are both high. The side effect is that a passionate engineer will also work to try and beat those goals.
    "

    Finally, someone accepting and using human nature.
    And see it works out...

    The fun part is that a requested functionality that is desired but can not make it within the expected timeframe, can still be worked on and can be ready for the next "bulge" in the market. This way you relieve your engineers form stress, you have the time to sort errors and bugs out, you have time to solve unforseen consequences that always happen( people can get sick, a bug in software, machines breaking down) and you have a feature for the market department to market to the consumer for the next iteration of the product. This way you can use the free market to build an in the end perfect device. It is all about balance. If you have to invest to much energy in situation a, you will have less energy for situation b in a certain timeframe. We are bound by laws of nature meaning there is no "perpetuum mobile" in this universe. Nothing comes for free...
    Reply
  • aegisofrime - Sunday, February 14, 2010 - link

    Anand, you have taken an article that is really technical in nature, and turned it into something entertaining to read and yet informative for non-engineer types. My hats off to you. This is really the right balance of information and readability. If only all the Scientific Papers I have to read were written like this! Reply
  • dukeariochofchaos - Sunday, February 14, 2010 - link

    i wonder if you will give fermi the same drama queen touch?

    i hope so.

    Reply
  • Jamahl - Sunday, February 14, 2010 - link

    I don't think anyone wants to read nvidia's marketing department tell us how awesome PhysX and CUDA is again tbh. Reply
  • TGressus - Sunday, February 14, 2010 - link

    I suspect Fermi will be able to stand on it's technological innovation.
    Reply
  • RJohnson - Sunday, February 14, 2010 - link

    ...and it's exorbitant price/die size will exclude mere mortals from owning one. Reply
  • Spoelie - Sunday, February 14, 2010 - link

    That depends entirely on the openness of NVIDIA on the subject, historically not one of their strong points.

    In fact ATi's take on NVIDIA's design process has been more informative than what has come out of NVIDIA itself.

    But here's to hoping..
    Reply

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