ARM’s Mali Midgard Architecture Explored
by Ryan Smith on July 3, 2014 11:00 AM EST
So far this is shaping up to be a banner year for SoCs. From a market perspective the mobile hardware space is still in a period of significant growth, but more importantly from a hardware point of view these products and especially the GPUs in these products have made significant strides in performance and in features. SoC GPUs will approach feature parity with desktop GPUs this year, and from a performance perspective they’re nearing the performance of the last-generation game consoles, a long-aspired goal given the “good enough” status attached to those devices.
Meanwhile at the same time that these products are maturing at a technical level, we’ve seen the various SoC firms mature at a professional level. The “wild west” days of SoCs have given way to mature markets of longer product cycles, longer product lives, and a more stable market overall. This both good and bad news for the various players in the SoC market as firms get squeezed out – SoC integrators such as TI and STMicroelectronics have been the first of such victims – but it also means that as companies become better established and more deeply entrenched, they can be more open about their projects and their products, and discuss them in greater detail than before without needing to be concerned about getting scooped by a competitor.
Here at AnandTech we’re particularly fond of doing architectural deep dives; our chance to talk to the people behind various processors and learn from them about how their products work and how they came together. Thanks to the maturation of the SoC market we’re finally getting a level of access in the SoC market that we haven’t had before, and in turn for the first time we get to tell the stories of the people behind these mind-bogglingly complex devices while better learning how they operate and as such how they compare. It’s admittedly a level of access we take for granted in the PC space, where companies such as Intel, AMD, and NVIDIA are regularly open, but it’s hard to contain our excitement about gaining this kind of access to the myriad of players in the SoC space.
This year then has been especially productive in that regard, and as of today it’s going to get even better. After we took a look at Imagination’s PowerVR Rogue architecture earlier this year, ARM contacted us and indicated that they would like to do the same; that they would like to take a seat at the “open architecture” table. To give us the access we need to discover how their GPUs work, and in turn tell you what we’ve learned.
To that end we’ve gladly let ARM pull up a seat, and today we’ll be taking our first in-depth look at ARM’s newest Mali SoC GPU architecture: Midgard. Now as with Imagination what we’re seeing today is most, but not all of the picture, as ARM has their secrets and they wish to keep some of them. But today we get to learn all about Midgard’s shader cores while also learning a thing or two about its pixel rendering pipeline, power optimizations, and other aspects of what makes Midgard tick. In other words, more than enough to keep us busy for one day.
But before we dive in we’d also like to quickly call attention to an Ask The Experts session we held with ARM’s Jem Davies, an ARM Fellow and VP of Technology in the Media Processing Division. While our deep dive is focusing on Midgard’s architecture, Jem has been answering all sorts of additional Mali-related questions, including business strategy and ARM’s views on GPU computing.
Finally, as this is the second article in our continuing series on SoC GPUs, we will be picking up from where we left off after our last article. While all of our articles are meant to be accessible to some degree, if you haven’t caught any of our previous articles I’d highly recommend our primer on how GPUs work for a quick overview of the technology before we dive into the nuts and bolts of ARM’s Midgard architecture.
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3DPowerFX - Thursday, July 3, 2014 - link
Once again, AnandTech has published a great article! Thanks ARM and AnandTech.Just one point. there is a small mistake in the article about Samsung Exynos 3470 GPU. It's not Mali 450MP but the undead Mali 400MP GPU. Although it would be nice to have the latest one.
Cogman - Thursday, July 3, 2014 - link
On transaction elimination. A movie is actually much worse about being eliminated than anything else. The only saving grace for a movie is the fact that the FPS are often much lower than what the device is natively putting out (so 60fps is a typical display refresh rate whereas movies typically operate at 24->30fps). After that, everything changes right down to the smallest detail. This is the grainy effect that you see in movies.For games, there could be some benefit assuming the game isn't a high action one. The biggest win will be still images (90% of what these displays are going to be displaying).
EdvardS - Thursday, July 3, 2014 - link
Movies are not actually that bad. Remember that videos we watch on our devices have already been compressed with lossy algorithms looking for temporal resemblance, which seems to boost the transaction elimination efficiency as well.BMNify - Thursday, July 3, 2014 - link
gem did a writup , but i cant find it now !, but take a look here as regards transaction elimination http://community.arm.com/groups/arm-mali-graphics/...BTW "the grainy effect that you see in movies" have absolutely nothing to do with frame rate
its put there (as in artificially) by the post processing due to the fact today everyone's using 8bit per pixel as in Rec. 709 (HDTV) color space that produces banding and other visible anomalies not the new official Rec. 2020 (UHDTV/UHD-1/UHD-2) real 10bit/12bit color space we will see soon.
tuxRoller - Thursday, July 3, 2014 - link
Consider asking red hat's rob clark. He's been reverse engineering the adreno arch (his driver, freedreno (https://github.com/freedreno/freedreno/wiki) however, is not a reverse engineered adreno driver) for a few years now and can almost certainly give you at least that much info.His blog is at http://bloggingthemonkey.blogspot.com, and he's a super nice guy.
jwcalla - Friday, July 4, 2014 - link
Qualcomm is a really closed company. They just did a massive DCMA takedown on GitHub: https://github.com/github/dmca/blob/master/2014-07...Their software side isn't that great either.
tuxRoller - Friday, July 4, 2014 - link
I'm not sure why this is addressed to me. Although I expect AT will ignore what I've written so as not to upset their corporate friends, what I suggested is what they should do if they are really interested in the tech.What's strange to me is that they did something similar with their analysis of Cyclone to what I'm suggesting they do, except in the Qualcomm case the work is done by someone else.
Death666Angel - Thursday, July 3, 2014 - link
Awesome to see this here! I hope the Adreno team will follow suite soon and lay their doubts to rest."LG’s Viewty" Holy shit, that way my 2nd ever phone (after my first flip phone got broken when I rammed a car with my bike). That thing was pretty bad all in all. But the slow motion camera was great for its time! :D It broke too while I was in a fight, but that was the last one. Touch Pro 2, Galaxy S2, Galaxy Nexus and LG G2 all working fine till this day. :D
Willardjuice - Thursday, July 3, 2014 - link
"From a sales perspective this means ARM can offer the CPU and GPU designs together in a bundle, but perhaps more importantly it means they have the capability design the two in concert with each other, being in the position of the sole creator of the ARM ISA."lol, the bundle aspect is far more important for ARM gpu sales. ;)
skiboysteve - Thursday, July 3, 2014 - link
Truth. Basically makes it so a competitor needs to show a significant performance, power, feature, or cost difference before it's worth an integrator investing in breaking apart the bundle