Intel's Haswell Architecture Analyzed: Building a New PC and a New Intel
by Anand Lal Shimpi on October 5, 2012 2:45 AM ESTFinal Words
After the show many seemed to feel like Intel short changed us at this year's IDF when it came to architecture details and disclosures. The problem is perspective. Shortly after I returned home from the show I heard an interesting comparison: Intel detailed quite a bit about an architecture that wouldn't be shipping for another 9 months, while Apple wouldn't say a thing about an SoC that was shipping in a week. That's probably an extreme comparison given that Apple has no motivation to share details about A6 (yet), but even if you compare Intel's openness at IDF to the rest of the chip makers we cover - there's a striking contrast. We'll always want more from Intel at IDF, but I do hope that we won't see a retreat as the rest of the industry seems to be ok with non-disclosure as standard practice.
There are three conclusions that have to be made when it comes to Haswell: its CPU architecture, its platform architecture and what it means for Intel's future. Two of the three look good from my perspective. The third one is not so clear.
Intel's execution has been relentless since 2006. That's over half a decade of iterating architectures, as promised, roughly once a year. Little, big, little, big, process, architecture, process, architecture, over and over again. It's a combination of great execution on the architecture side combined with great enabling by Intel's manufacturing group. Haswell will continue to carry the torch in this regard.
The Haswell micro-architecture focuses primarily on widening the execution engine that has been with us, moderately changed, for the past several years. Increasing data structures and buffers inside the processor helps to feed the beast, as does a tremendous increase in cache bandwidth. Support for new instructions in AVX2 via Intel's TSX should also pave the way for some big performance gains going forward. Power consumption is also a serious target for Haswell given that it must improve performance without dramatically increasing TDP. There will be slight TDP increases across the board for traditional form factors, while ultra portables will obviously shift to lower TDPs. Idle power drops while active power should obviously be higher than Ivy Bridge.
You can expect CPU performance to increase by around 5 - 15% at the same clock speed as Ivy Bridge. Graphics performance will see a far larger boost (at least in the high-end GT3 configuration) of up to 2x vs. Intel's HD 4000 in a standard voltage/TDP system. GPU performance in Ultrabooks will increase by up to 30% over HD 4000.
As a desktop or notebook microprocessor, Haswell looks very good. The architecture remains focused and delivers a sensible set of improvements over its predecessor.
As a platform, Haswell looks awesome. While the standard Haswell parts won't drive platform power down considerably, the new Haswell U/ULT parts will. Intel is promising a greater than 20x reduction in platform idle power and it's planning on delivering it by focusing its power reduction efforts beyond Intel manufactured components. Haswell Ultrabooks and tablets will have Intel's influence in many (most?) of the components placed on the motherboard. And honestly, this is something Intel (or one of its OEMs) should have done long ago. Driving down platform power is a problem that extends beyond the CPU or chipset, and it's one that requires a holistic solution. With Haswell, Intel appears committed to delivering that solution. It's not for purely altruistic reasons, but for the survival of the PC. I remember talking to Vivek about an iPad as a notebook replacement piece he was doing a while back. The biggest advantage the iPad offered over a notebook in his eyes? Battery life. Even for light workloads today's most power efficient ultraportable notebooks can't touch a good ARM based tablet. Haswell U/ULT's significant reduction in platform power is intended to fix that. I don't know that we'll get to 10+ hours of battery life on a single charge, but we should be much better off than we are today.
Connected standby is coming to PCs and it's a truly necessary addition. Haswell's support of active idle states (S0ix) is a game changer for the way portable PCs work. The bigger concern is whether or not the OEMs and ISVs will do their best to really take advantage of what Haswell offers. I know one will, but will the rest? Intel's increasingly hands on approach to OEM relations seems to be its way of ensuring we'll see Haswell live up to its potential.
Haswell, on paper, appears to do everything Intel needs to evolve the mobile PC platform. What's unclear is how far down the TDP stack Intel will be able to take the architecture. Intel seems to believe that TDPs below 8W are attainable, but it's too early to tell just how low Haswell can go. It's more than likely that Intel knows and just doesn't want to share at this point. I don't believe we'll see fanless Haswell designs, but Broadwell is another story entirely.
There's no diagram for where we go from here. Intel originally claimed that Atom would service an expanded range of TDPs all the way up to 10W. With Core architectures dipping below 10W, I do wonder if that slide was a bit of misdirection. I wonder if, instead, the real goal is to drive Core well into Atom territory. If Intel wants to solve its ARM problem, that would appear to be a very good solution.
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FunBunny2 - Friday, October 5, 2012 - link
While not a hardware issue (and thus not an AnandTech major venue), I would be amused if one of your writers explored the implications on data storage design (normal form databases vs. traditional files) of small real estate mobile. My take is that small, consistent bites of bytes are required, and will eventually change how data is stored on the servers. Any takers?lukarak - Saturday, October 6, 2012 - link
In other words, "....all cars were trucks....."?BoloMKXXVIII - Friday, October 5, 2012 - link
Very well written article. Other sites should read Anandtech to see how it should be done.Thank you.
All this power saving in idle conditions is great (love the looping of frame buffer idea), but users aren't always reading text on their screens. When these chips are under load they are still going to draw very significant amounts of power. Unless battery technology improves by an order of magnatude I don't see Haswell (or its replacements) fitting into ultraportable devices like phones or "phablets". The other comments concerning AMD are on the mark. AMD is in big trouble. They are too far behind Intel right now and every indication is they will be falling further behind.
silverblue - Friday, October 5, 2012 - link
Steamroller will haul AMD back towards Intel. Not completely, but a lot closer than they have been, and potentially even ahead in some cases. Still, that process deficit has to be painful, as AMD can only win on idle power.I really hope GF don't mess up again, as delays really are costing AMD dearly. Steamroller is a good design, the sort that means AMD can have a cheaper but still decent part, but I fear it'll come too late.
Intel CPUs are looking even more tasty than ever.
overseer - Friday, October 5, 2012 - link
Great Article.Then I sincerely hope AMD can still survive and stride forward in this mobile tide. (R.R. and J.K., you reading this?)
It may look silly but I do like underdogs and their (solid) products, especially when they achieved something with less talents, capital and executiveness.
wumpus - Friday, October 5, 2012 - link
"To put it in perspective, you'll be able to get something faster than an Ivy Bridge Ultrabook or MacBook Air, in something the size of your smartphone, in fewer than 8 years". I can tell you right now, while this architecture is absolutely great on a motherboard, this isn't the right path to the mobile space."Haswell is the first step of a long term solution to the ARM problem." Unfortunately, anandtech is one of the few places left that can call intel on this marketing blather. Intel's ARM problem is that there is no more efficient way to execute instructions than on a in-order, single instruction issue, clean RISC design: all of which are standard features on an ARM. ARM's intel problem is that this limits you to about .5GIPS ([G]meanless indicator of processor speed) compared to over 6GIPS on an all out Intel design.
The choice isn't all or nothing, just that this time Intel choose performance over efficiency. MIPS, alpha, (to a large part) PowerPC all fell to high performance Intel chips that were vastly less complex than current designs. ARM could try to compete with Intel on performance, but if they are lucky they will end up like AMD, and if they can't out design Intel (remember Intel's process advantage) they will end up like MIPS, etc.
The reason this all appears to be built around speed (and not efficiency) can be found on pages 7 and 8 (despite protests listed on those pages). Intel needs to add wider execution paths to try to get a tiny few more instructions out per second, all the while holding even more (than ivy or sandy) instructions in flight in case it can execute one. All this means a much longer path for any instruction and many more things computed, more leaky transistors leaking picoamps, more latches burning nanowatts. All ARM has to do is execute one after another.
I am surprised that they bothered to toot their horn about the GPU. It might beat ARM, but any code that can be made to fit a GPU should be run on an AMD machine (or possibly discrete nVidia board). They have been pushing Intel graphics for at least 15 years, don't pretend they are ever going to get it right.
In conclusion, I want one of these in my desktop. A phone CPU should look much more like an early core (maybe core2) design, maybe even more like a pentium pro.
A5 - Friday, October 5, 2012 - link
If we're going to start a RISC/CISC battle, you should really look at a modern ARM architecture before talking.What you can fit in a phone today isn't going to be what you can fit in a phone 8 years from now (in terms of both TDP and die size).
Getting Haswell-class performance from a 2020 smartphone isn't that far-fetched...you can argue that modern smartphone SoCs are close to the performance of the Athlon 64 2800+ or the Prescott Pentium 4s of 2004 in a lot of tasks.
wumpus - Friday, October 5, 2012 - link
There is a reason Atom is getting creamed in the phone space by ARM. Also the only way TDP is going to change is with major increases in battery technology. X Joules (typically changed to W/hr in battery speak, but why not stick with SI units) means X seconds a 1 W or X/n seconds at n Watts.On the high end, everything that won the war for CISC (namely, Intel's manufacturing skills) is even more true than when they won. There isn't going to be another. That doesn't mean that a chip designed for all out performance is going to have any business competing with ARM on MIP/W. If they wanted to compete on battery life, they would have scaled down the depth and breadth of the queue, not increased it.
Actually, I was ready to go into full rant when I saw the opening. Then I checked that "ultrabook" meant 1.8GHz i3s. It is quite possible (although I still doubt it is a good way to use a battery) to build a chip that will do that and have low power. I just don't think that Haskel is anyway designed to be that chip
FunBunny2 - Friday, October 5, 2012 - link
-- everything that won the war for CISC (namely, Intel's manufacturing skills) is even more true than when they wonIt's been true since P4 that the "real" cpu is a RISC engine fronted by a x86 ISA translator. Intel tried to sell a ISA level RISC chip (twice). Not so hot. But Intel does know RISC. I've always wondered why they used all that transistor budget the way they did, rather than doing the entire instruction set in hardware, as they could have. It's as if IBM turned all the 370s into 360/30s.
Penti - Saturday, October 6, 2012 - link
It was Pentium Pro that switched to a modern out of order micro-ops powered CPU. I.e. P6. It's only the front end that speaks x86. Intel's own RISC designs like i960 ultimately failed and EPIC even more so when it failed to outdo AMD and Intel server processors in enterprise applications. In reality customers only switched to Itanium because they already had made up their mind before there even was any product thus killing at the time more appropriate Alpha, MIPS and PA-RISC processors. But as soon as those where fased out, Intel's x86 compatible chips had already gained the enterprise features that it missed previously and that set those older chips apart.The front end and x86 decode doesn't use that much space in modern processors at all. CPU architecture aren't really all that important it's today largely about the features it supports, the gpu, video decode/processor etc. ARM just made it into the out-of-order superscalar era in 2011 with A9, superscalar in-order in 2008 with Cortex A8. Atom is kinda designed like a P5 cpu. I.e. superscalar in-order, and moves to an out-of-order design next year. Intel's first superscalar design was in 1988.
ARM just needs to be fast enough, it was fairly easy to replace SH3, Motorola DragonBall, i386 design in the mobile space it was even Intel that did it to a large part. And earlier 8086-stuff had already been left behind by that time. Now what's impressive is the integration and finish of the ARM SoC's. It was Intel that didn't want companies like Research In Motion to continue use low-power Intel x86-chips in their handheld devices. That only changes when Intel sold off the StrongARM/XScale line in 2006. Intel has no reason to start create custom ARM ISA chips again as they can compete with them with x86 chips which they spend much larger time to adapt development tools and frameworks for any way. Atom as a whole has a much larger market then XScale had on it's own. Remember that Intel dropped stuff like RAID/Storage-processors too. Having Intel as a Marvell in ARM chips today wouldn't have changed anything radically.