Intel's Haswell Architecture Analyzed: Building a New PC and a New Intel
by Anand Lal Shimpi on October 5, 2012 2:45 AM ESTPrioritizing 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%.
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Magik_Breezy - Sunday, October 14, 2012 - link
Probably real customer support without paying an extra $200Spunjji - Thursday, October 18, 2012 - link
Yawn.Spunjji - Thursday, October 18, 2012 - link
The bit that aggravates me the most is that even with this lavishing of review pages, the actual comparison of Apple products to competitors tends to lack (particularly with the Macbook article). This is understandable under some circumstances (iPhone battery life - new test, small selection of data points) but not for others.Arbee - Friday, October 5, 2012 - link
I'm not really seeing any of that. AT's Android and Windows Phone reviews are just as in-depth and complementary where due as their Apple ones. AFAIK both Anand's and Brian's daily-driver phones aren't iPhones, even. They care about the tech, not who it comes from. It just happens that Apple is often the original source of new and interesting things in that space. At this exact moment they're the only people shipping something new and interesting. When the Nokia 920 launches, I'm confident Anand and Brian will be ready with a 15+ page review and discussion of anything novel on the podcast, and when Winter CES brings us Tegra 4 and other Android news, I expect to see eye-glazing levels of detail here at AT.(As an aside, I smiled at how closely DPReview's discussion of the alleged "purple haze" problem tracked Brian's rant on the podcast - clearly both writers know what they're talking about, which can be a rare quantity in tech journalism).
VivekGowri - Saturday, October 6, 2012 - link
I think Anand's daily driver is an iPhone, but he frequently carries the latest Android/WP device on the side. Brian and myself end up daily driving like a half dozen phones a month, depending on what shows up at our doorstep.Zink - Saturday, October 6, 2012 - link
"iPad 3 form factor" was used because all of the other tablets have 25Wh batteries and draw about 5W max. The A5X iPad and it's giant 42.5Wh battery on the other hand can put out over 10W of heat which is the power envelope where Intel might target a Haswell SOC.amdwilliam1985 - Monday, October 8, 2012 - link
I totally agree with you on the Apple part. That's the biggest pullback on reading Anand writings. Too much Apple praising.I used to be an Apple fan, but recently they're becoming the biggest jerks in the technology industry. The human/ethical part of in me hates them so much, that I won't buy anything that has a Apple logo on it.
I gave away my iPad 2, switched to Samsung Galaxy S phones, and using my HP windows 7 laptop over the 2011 MBA.
-say NO to bully, say NO to Apple.
xaml - Thursday, May 23, 2013 - link
Number of problems solved with this approach: NO.dartox - Tuesday, November 27, 2012 - link
Probably because most people know about how large an iPad is - if he said "tablet" form factor that's ambigious.. and if he said "Motorola XOOM" form factor not as many people are familiar with the size.Paer0 - Friday, October 5, 2012 - link
Yes... Macs are well engineered and deliver a solid performance across board.