Intel's Haswell Architecture Analyzed: Building a New PC and a New Intel
by Anand Lal Shimpi on October 5, 2012 2:45 AM ESTHaswell's GPU
Although Intel provided a good amount of detail on the CPU enhancements to Haswell, the graphics discussion at IDF was fairly limited. That being said, there's still some to talk about here.
Haswell builds on the same fundamental GPU architecture we saw in Ivy Bridge. We won't see a dramatic redesign/re-plumbing of the graphics hardware until Broadwell in 2014 (that one is going to be a big one).
Haswell's GPU will be available in three physical configurations: GT1, GT2 and GT3. Although Intel mentioned that the Haswell GT3 config would have twice the shader count of Haswell GT2, it was careful not to disclose the total number of EUs in any of the versions. Based on the information we have at this point, GT3 should be a 40 EU configuration while GT2 should feature 20 EUs. Intel will also be including up to one redundant EU to deal with the case where there's a defect in an EU in the array. This isn't an uncommon practice, but it does indicate just how much of the die will be dedicated to graphics in Haswell. The larger of an area the GPU covers, the greater the likelihood that you'll see unrecoverable defects in the GPU. Redundancy at the EU level is one way of mitigating that problem.
Haswell's processor graphics extends API support to DirectX 11.1, OpenCL 1.2 and OpenGL 4.0.
At the front of the graphics pipeline is a new resource streamer. The RS offloads some driver work that the CPU would normally handle and moves it to GPU hardware instead. Both AMD and NVIDIA have significant command processors so this doesn't appear to be an Intel advantage although the devil is in the (unshared) details. The point from Intel's perspective is that any amount of processing it can shift away from general purpose CPU hardware and onto the GPU can save power (CPU cores go to sleep while the RS/CS do their job).
Beyond the resource streamer, most of the fixed function graphics hardware sees a doubling of performance in Haswell.
At the shader core level, Intel separates the GPU design into two sections: slice common and sub-slice. Slice common includes the rasterizer, pixel back end and GPU L3 cache. The sub-slice includes all of the EUs, instruction caches and EUs.
In Haswell GT1 and GT2 there's a single slice common, while GT3 sees a doubling of slice common. GT3 similarly has two sub-slices, although once again Intel isn't talking specifics about EU counts or clock speeds between GT1/2/3.
The final bit of detail Intel gave out about Haswell's GPU is the texture sampler sees up to a 4x improvement in throughput over Ivy Bridge in some modes.
Now to the things that Intel didn't let loose at IDF. Although originally an option for Ivy Bridge (but higher ups at Intel killed plans for it) was a GT3 part with some form of embedded DRAM. Rumor has it that Apple was the only customer who really demanded it at the time, and Intel wasn't willing to build a SKU just for Apple.
Haswell will do what Ivy Bridge didn't. You'll see a version of Haswell with up to 128MB of embedded DRAM, with a lot of bandwidth available between it and the core. Both the CPU and GPU will be able to access this embedded DRAM, although there are obvious implications for graphics.
Overall performance gains should be about 2x for GT3 (presumably with eDRAM) over HD 4000 in a high TDP part. In Ultrabooks those gains will be limited to around 30% max given the strict power limits.
As for why Intel isn't talking about embedded DRAM on Haswell, your guess is as good as mine. The likely release timeframe for Haswell is close to June 2013, there's still tons of time between now and then. It looks like Intel still has a desire to remain quiet on some fronts.
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A5 - Friday, October 5, 2012 - link
8 years is a loooooong time in this space, and yes you (and most people here) are in the minority.Notebooks have been outselling desktops for several years, and in 2011 smartphone shipments were higher than all PC form-factors combined. It's pretty clear where the big bucks are going, and it isn't desktop PCs.
flamethrower - Friday, October 5, 2012 - link
In 8 years you'll have 50-inch OLED TVs on your walls. What's going to drive them? Possibly a computer integrated into them.Peanutsrevenge - Friday, October 5, 2012 - link
We'll just be using large screens, keyboards and mice wireless connected to our ultra portable devices.The desktop will likely still exist for people like us who frequent this site, however it's role will be far more specialised, possibly more as our personal cloud servers than our PCs.
yankeeDDL - Friday, October 5, 2012 - link
Wow. Thanks for the excellent article: I really enjoyed it.The thought of having a processor of the power level of Ivy bridge in my mobile phone blows my mind.
Honestly though, I really can't see how the volume of CPUs for desktop PCs and servers is going to drop so dramatically, that Intel will need the volume generated by mobile, to "survive".
Yes, of course more volume will help, but 8 years from now, even if the mobiles will have such kind of computational power, I would imagine that a Desktop would have 10~20x that performance, as it is today.
It's true that today's CPUs are typically more powerful than the average user ever needs, but raise the hand who wouldn't trade his CPU for one 10x faster (in the same power envelope) ...
That said, 10W still seems like a lot to fit in a mobile: who knows the power consumption of high-end mobile CPUs today? (quad-core Krait CPU, for example, or even Tegra3)
dagamer34 - Friday, October 5, 2012 - link
Intel's real problem is that the power needed for "good enough" computing in a typical desktop CPU came a couple of years ago Nd is rapidly approaching in mobile. With more and more tasks being offloaded to the cloud, battery life is becoming a stronger and stronger focus.What's sad is that because AMD isn't the major player it once was, Intel has allowed it's eye off the ball, revving Atom with only minor tweaks and having a laissez faire approach to GPU performance. It's only been recently when mobile has started to dominate in the minds of consumers and Intel's lack of any major design wins (the RAZR I doesn't count) which has forced Intel to push as hard as it is now.
sp3x0ps - Friday, October 5, 2012 - link
Where is the iPhone 5 review? I need details!! arghh.Demon-Xanth - Friday, October 5, 2012 - link
Atom was targeted to UMPCs, but quickly took over low power embedded systems who don't need much power but do run Windows.tipoo - Friday, October 5, 2012 - link
Poor Via.dgingeri - Friday, October 5, 2012 - link
"Within 8 years many expect all mainstream computing to move to smartphones, or whatever other ultra portable form factor computing device we're carrying around at that point."They said the same thing about laptops. Sure, laptops hold about 60-65% of the market these days, but the desktop is still very much around, and is the preferred platform for PC gamers and HTPC applications. They're far more flexible than any mobile form factor.
Smartphones also have the severe disadvantage of a very small screen. Even the largest are too small for most people to deal with. On top of that, actually surfing the net on those tiny screens is an exercise in frustration for many people. I try to tap on a link, only to get the link next to it, or above it, or below it, or possibly having my stupid phone just select the text instead of following the link.
Smartphones have their niche. There's no doubt there, but they are not going to be anyone's mainstream device unless they have needle thin fingers and 20/10 vision.
Anand Lal Shimpi - Friday, October 5, 2012 - link
I agree with the notebook/desktop comparison - these form factors won't go away. I should have said the majority of mainstream client computing goes to smartphones. And solving the display and input problems is easy: wireless display (WiDi/Miracast) and wireless keyboard/mouse (or a dock that does both over wires if you'd rather that).Take care,
Anand