Prioritizing ILP

Intel has held the single threaded performance crown for years now, but the why is really quite easy to understand: it has prioritized extracting instruction level parallelism with every generation. Couple that with the fact that every two years we see a "new" microprocessor architecture from Intel and there's a recipe for some good old evolutionary gains. The table below shows the increase in size of some major data structures inside Intel's architectures for every tock since Conroe:

Intel Core Architecture Buffer Sizes
  Conroe Nehalem Sandy Bridge Haswell
Out-of-order Window 96 128 168 192
In-flight Loads 32 48 64 72
In-flight Stores 20 32 36 42
Scheduler Entries 32 36 54 60
Integer Register File N/A N/A 160 168
FP Register File N/A N/A 144 168
Allocation Queue ? 28/thread 28/thread 56

Increasing the OoO window allows the execution units to extract more parallelism and thus improve single threaded performance. Each generation Intel is simply dedicating additional transistors to increasing these structures and thus better feeding the beast.

This isn't rocket science, but it is enabled by Intel's clockwork fab execution. Designers can count on another 30% die area to work with every 2 years, so every 2 years they increase the size of these structures without worrying about ballooning the die. The beauty of evolutionary improvements like this is that when viewed over the long term they look downright revolutionary. Comparing Haswell to Conroe, the OoO scheduling window has grown by a factor of 2x, despite generation to generation gains of only 14 - 33%.

The Haswell Front End Haswell's Wide Execution Engine
POST A COMMENT

247 Comments

View All Comments

  • kylewat - Tuesday, February 12, 2013 - link

    Why is Appl the largest market cap company in the world? Reply
  • Spunjji - Thursday, October 18, 2012 - link

    Fuckwit. Reply
  • nirmalv - Sunday, October 07, 2012 - link

    Anandtech being a hardware site,its more inclined to keenly flow hardware devices with new architecture and innovations. iphone brings in
    1, A new A7 chip design and a novel 3 core graphics core
    2, A new 3 microphone parabolic sound receiving design(which likely will become the new standard)
    3, A new sim tray design(which will also likely become the new standard)
    4, New sony BSI stacked sensor (the 13 mpx version will likely be the rage next year).
    5, The first time that we have a 32 nm LTE chip which will give all day usage.
    6, New thinner screen with incorporated touch panel and 100 % RGB

    I am not sure about samsung but can anyone enlighten me about S3's technical achievements?
    Reply
  • nirmalv - Sunday, October 07, 2012 - link

    Sorry make that a 28 nm LTE baseband Reply
  • centhar - Sunday, October 07, 2012 - link

    99.998% of iPhone users just don't care about that. Really they don't.

    Geeks like me who do, are too damn smart to sell our souls to the such a god damned, locked down and closed system to even bother to care.
    Reply
  • Magik_Breezy - Sunday, October 14, 2012 - link

    2nd that Reply
  • Spunjji - Thursday, October 18, 2012 - link

    3rd Reply
  • CaptainDoug - Tuesday, October 23, 2012 - link

    4th, Reply
  • solipsism - Tuesday, October 09, 2012 - link

    Of course a company that releases one device per product category per year as well as one with the greatest mindshare is going to have more articles.

    But what happens when you add up all Samsung phones against all Apple phones in a given year?

    What happens when you don't count the small blogs that only detail a small aspect of a secretive product but count the total words to get a better feel for the effort spent per company's market segment?

    I bet you'll find that AT spends a lot more time covering Samsung's phones than Apple's.
    Reply
  • Spunjji - Thursday, October 18, 2012 - link

    This. I generally trust their editorial, but the focus on Apple prevails. One just has to read accordingly. Reply

Log in

Don't have an account? Sign up now