Driving the Retina Display: A Performance Discussion

As I mentioned earlier, there are quality implications of choosing the higher-than-best resolution options in OS X. At 1680 x 1050 and 1920 x 1200 the screen is drawn with 4x the number of pixels, elements are scaled appropriately, and the result is downscaled to 2880 x 1800. The quality impact is negligible however, especially if you actually need the added real estate. As you’d expect, there is also a performance penalty.

At the default setting, either Intel’s HD 4000 or NVIDIA’s GeForce GT 650M already have to render and display far more pixels than either GPU was ever intended to. At the 1680 and 1920 settings however the GPUs are doing more work than even their high-end desktop counterparts are used to. In writing this article it finally dawned on me exactly what has been happening at Intel over the past few years.

Steve Jobs set a path to bringing high resolution displays to all of Apple’s products, likely beginning several years ago. There was a period of time when Apple kept hiring ex-ATI/AMD Graphics CTOs, first Bob Drebin and then Raja Koduri (although less public, Apple also hired chief CPU architects from AMD and ARM among other companies - but that’s another story for another time). You typically hire smart GPU guys if you’re building a GPU, the alternative is to hire them if you need to be able to work with existing GPU vendors to deliver the performance necessary to fulfill your dreams of GPU dominance.

In 2007 Intel promised to deliver a 10x improvement in integrated graphics performance by 2010:

In 2009 Apple hired Drebin and Koduri.

In 2010 Intel announced that the curve had shifted. Instead of 10x by 2010 the number was now 25x. Intel’s ramp was accelerated, and it stopped providing updates on just how aggressive it would be in the future. Paul Otellini’s keynote from IDF 2010 gave us all a hint of what’s to come (emphasis mine):

But there has been a fundamental shift since 2007. Great graphics performance is required, but it isn't sufficient anymore. If you look at what users are demanding, they are demanding an increasingly good experience, robust experience, across the spectrum of visual computing. Users care about everything they see on the screen, not just 3D graphics. And so delivering a great visual experience requires media performance of all types: in games, in video playback, in video transcoding, in media editing, in 3D graphics, and in display. And Intel is committed to delivering leadership platforms in visual computing, not just in PCs, but across the continuum.

Otellini’s keynote would set the tone for the next few years of Intel’s evolution as a company. Even after this keynote Intel made a lot of adjustments to its roadmap, heavily influenced by Apple. Mobile SoCs got more aggressive on the graphics front as did their desktop/notebook counterparts.

At each IDF I kept hearing about how Apple was the biggest motivator behind Intel’s move into the GPU space, but I never really understood the connection until now. The driving factor wasn’t just the demands of current applications, but rather a dramatic increase in display resolution across the lineup. It’s why Apple has been at the forefront of GPU adoption in its iDevices, and it’s why Apple has been pushing Intel so very hard on the integrated graphics revolution. If there’s any one OEM we can thank for having a significant impact on Intel’s roadmap, it’s Apple. And it’s just getting started.

Sandy Bridge and Ivy Bridge were both good steps for Intel, but Haswell and Broadwell are the designs that Apple truly wanted. As fond as Apple has been of using discrete GPUs in notebooks, it would rather get rid of them if at all possible. For many SKUs Apple has already done so. Haswell and Broadwell will allow Apple to bring integration to even some of the Pro-level notebooks.

To be quite honest, the hardware in the rMBP isn’t enough to deliver a consistently smooth experience across all applications. At 2880 x 1800 most interactions are smooth but things like zooming windows or scrolling on certain web pages is clearly sub-30fps. At the higher scaled resolutions, since the GPU has to render as much as 9.2MP, even UI performance can be sluggish. There’s simply nothing that can be done at this point - Apple is pushing the limits of the hardware we have available today, far beyond what any other OEM has done. Future iterations of the Retina Display MacBook Pro will have faster hardware with embedded DRAM that will help mitigate this problem. But there are other limitations: many elements of screen drawing are still done on the CPU, and as largely serial architectures their ability to scale performance with dramatically higher resolutions is limited.

Some elements of drawing in Safari for example aren’t handled by the GPU. Quickly scrolling up and down on the AnandTech home page will peg one of the four IVB cores in the rMBP at 100%:

The GPU has an easy time with its part of the process but the CPU’s workload is borderline too much for a single core to handle. Throw a more complex website at it and things get bad quickly. Facebook combines a lot of compressed images with text - every single image is decompressed on the CPU before being handed off to the GPU. Combine that with other elements that are processed on the CPU and you get a recipe for choppy scrolling.

To quantify exactly what I was seeing I measured frame rate while scrolling as quickly as possible through my Facebook news feed in Safari on the rMBP as well as my 2011 15-inch High Res MacBook Pro. While last year’s MBP delivered anywhere from 46 - 60 fps during this test, the rMBP hovered around 20 fps (18 - 24 fps was the typical range).


Scrolling in Safari on a 2011, High Res MBP - 51 fps


Scrolling in Safari on the rMBP - 21 fps

Remember at 2880 x 1800 there are simply more pixels to push and more work to be done by both the CPU and the GPU. It’s even worse in those applications that have higher quality assets: the CPU now has to decode images at 4x the resolution of what it’s used to. Future CPUs will take this added workload into account, but it’ll take time to get there.

The good news is Mountain Lion provides some relief. At WWDC Apple mentioned the next version of Safari is ridiculously fast, but it wasn’t specific about why. It turns out that Safari leverages Core Animation in Mountain Lion and more GPU accelerated as a result. Facebook is still a challenge because of the mixture of CPU decoded images and a standard web page, but the experience is a bit better. Repeating the same test as above I measured anywhere from 20 - 30 fps while scrolling through Facebook on ML’s Safari.

Whereas I would consider the rMBP experience under Lion to be borderline unacceptable, everything is significantly better under Mountain Lion. Don’t expect buttery smoothness across the board, you’re still asking a lot of the CPU and GPU, but it’s a lot better.

Achieving Retina Boot Camp Behavior & Software Funniness
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  • Sabresiberian - Tuesday, June 26, 2012 - link

    Haven't been interested in anything Apple since the Lisa, but I'm actually tempted to get one of these - which is saying a lot because I'm not a fan of the company at all.

    One thing for sure; I'm sure not interested in buying a different laptop made by someone else with a lousy display! You want my business, I suggest you at least follow Apple's lead here.

    I couldn't agree with Anand more on the state of quality of monitors in general - and the fact that you can buy a (Korean) 2560x1440 monitor now for $300, including shipping from S. Korea, tells the story on affordability there.

    ;)
    Reply
  • orthorim - Wednesday, June 27, 2012 - link

    Compared to this review, all the others out there are more or less a variation of "ohhhh... shiny!".

    Thanks for this fantastic in-depth article, AnandTech!
    Reply
  • darwiniandude - Friday, June 29, 2012 - link

    Still waiting for mine to arrive, although I've used the rMBP a fair bit in the mean time.

    Not sure why 1/3rd of the comments are about a Sony Z series, and couldn't see mention of real word battery life tests?

    Regardless, 1st gen rMBP is an awesome product, and just like with the 1st MacBook Air, this model will look terrible compared to its 2nd or 3rd gen. Can't wait.
    Reply
  • danrhiggins - Saturday, June 30, 2012 - link

    I have been trying to talk myself into buying the MBR for two weeks now to replace my 2011 17" MBP (to which I added SSD) because the 17" is just a bit too large/heavy to carry around. I use the 17" mostly for my photography hobby.

    The problem is that my main computer is a 13" Macbook air and I jumped on the new 2012 MBA - which I love. So after reading your article I took my 2012 MBA down to the Apple store and put it alongside the MBR on display. Then I brought up ESPN.com and created a couple of matching "virtual" desktops all in full screen mode. (I used MS Excel and one of the included templates for one of the windows as that would be mostly the same on both machines.)

    Then I scrolled up and down and swiped from left to right on both machines at the same time. I wanted to see if any of the issues described here manifested themselves in this admittedly crude comparison. I tried different resolutions on the MBR. (I would not be interested in the "Best for Retina" as I would be looking for more screen real estate.) I also tried it with graphics switching turned on and off.

    Where scrolling on the MBA was very smooth, be it up/down scrolling in Safari or in Excel or side to side scrolling between desktops, the MBR was noticeably jittery in comparison. It reminded me of when my HD cable signal has a bit of interference and can't quite keep up.

    To those coming from older MBP's this may not be an issue. But having grown accustomed to the much smoother operation (IMHO) of the MBA the MBA wins. For now. Yes, they are different machines with different goals. But I don't need the extra I/O ports (1 Thunderbolt and 2 USB 3 is enough given that I use BT keyboard and trackpad) and a Thunderbolt display as a "docking station".

    I look forward to the day that the MBR will have the smooth graphics of the MBA and have addressed any other issues. Then I will get one to replace my 17" MBP. Maybe Mountain Lion and a firmware upgrade or two will clean this up. Or maybe not until the next generation or two. Then the hardware and the software (including 3rd party) will catch up.

    Thanks again for your review. I was going to buy one today. They had what I needed at the Apple Store. But because of your review I did this test and I'm glad I did. Now I'll wait. And there will be one more available for all of those anxious to upgrade.
    Reply
  • marraco - Sunday, July 01, 2012 - link

    The retina display is a waste with that crappy Intel video. Reply
  • Fingalterre - Sunday, July 01, 2012 - link

    I have the Z from 2010. It is still as faster or as fast with its graphics and i620 processor as the latest Air or 13" Pro to which it is directly comparable. What the Z lacks is the multitouch ability and the scalability of the Air or Retina Pro. What I am left with is a computer whose graphics are too small to read and a mousepad too small to scroll with easily. Also, after using Windows and Lion, I think Windows 7 is just not as user friendly as OS X. The form factor of the Air and Retina Pro are also a joy when you travel, which I do much. The Mac App store, though limited compared to the IOS, also is something Sony just doesn't have.

    I have been a Windows user for 20 years after Apple lost me with their limited selection and miscues. I still have my reservations about their corporate culture, but right now, they are producing superior products, a well thought out support network, and works of beauty of art, which distinguish them from all other OEMs. Dell once did this--my wife kept her Dell 5150 laptop for 7 years, only to trade it in for a 17 in XPS which didn't work and which was not well supported,, and then to a Mac Book Air in 2010, which has met her every need (as a high end IT security person). My Retina Pro arrives on July 20 and my Z is going to Ebay to pay for it.
    Reply
  • negativeions - Monday, July 02, 2012 - link

    What is the point in retina? Who cares. I mean it's ok, but the scaling is so utterly stupid it's beyond belief. Why in God's name don't Apple just program proper resolution independence into OSX... Then you could have any bloody user space you want with any resolution. Reply
  • Steelbom - Monday, July 02, 2012 - link

    What's the point? It looks fantastic. And why is the scaling stupid? It's a pretty great way to handle it. Reply
  • gunny2k6 - Tuesday, July 03, 2012 - link

    http://www.eurocom.com/products/index.htm
    check the EUROCOM Panther 3.0

    talk about apple making high end partts in laptops i call BS ... this compnay and many others like Clevo and Lenovo before they bourght IBM's pc hardware side ... have been putting high end things in laptops since the BLOODY Pentium 4 Northwood !!!!

    http://www.clevo.com.tw/en/index.asp
    http://www.pcspecialist.co.uk/notebooks/vortexIII-...

    THEY ALL BEEN DOING IT FOR YEARS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! before apple moved to intel !

    yes not for everyone as there big heavy and expensive what jobs did was bring those peoples ides to the masses !! when they moved to Intel .... they kept the high price tag from the PowerPC to the cheaper to make Intel based system and then used that spare cash for R&D to make the above ideas work for the masses !!
    Reply
  • gunny2k6 - Tuesday, July 03, 2012 - link

    for got to say let me guess a years time we will see apple do something like this and all the praise will go to Apple for "inventing it " Reply

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