"Hardware Architectures for Deep Neural Networks"

This presentation from MIT provides an excellent overview of current techniques and hardware implementations for efficient deep learning computation. There is also an associated paper.

The material requires familiarity with the basics of deep learning and its terminology. Provided you are familiar, though, the presentation is very accessible and easy to follow even if you aren't a machine learning researcher.

“How is ARCore better than ARKit?”

These are basically the same conclusions I’ve drawn over the past couple days and shared with subscribers. Despite the insecurities of fanboys on both sides, ARKit and ARCore seem pretty comparable overall.

It’s refreshing to see technical blogging that’s fair to all sides, and thus actually accurate. The statements made also match up completely with my limited understanding of AR and hardware product development. I recommend reading the entire article to see what I mean.

I did a little digging yesterday, and there doesn’t seem to be much to ARCore’s Nougat API requirement. Android device support probably boils down to Google’s dedication to validation, and not really hardware or fragmentation.

I’ve also been writing on AR and hardware for subscribers, so check that out if you're interested.

Will the iMac Pro throttle?

As was expected to happen at some point, Intel today introduced its new Xeon-W workstation CPUs.

Intel has had to overhaul its product portfolio due to the massive challenges and delays of its 10nm process. Apple actually pre-announced these new Xeons at WWDC while giving minimal detail. It was clear, however, that the CPUs would essentially be Skylake-X.

Xeon CPUs are not “faster” than Core CPUs, because they use the same microarchitecture. Xeon chipsets, however, come with important features for workstations and servers such as ECC RAM.

To oversimplify, Intel advertises TDPs (thermal design power ratings) of up to 140W for a Xeon-W. AMD’s Vega 56 and 64 GPUs are rated at TBPs (thermal board power ratings) of 210W and 295W, respectively*.

For the iMac Pro, Apple has redesigned the airflow of the chassis and finally added a second fan. Philosophically, though, the company has a low tolerance for fan noise.

Will the iMac Pro significantly throttle? We’ll see.


* I’m only referencing the official vendor thermal ratings, and TDP and TBP mean different things.


From my perspective, AMD is currently the most fascinating company in tech. Its Zen CPU microarchitecture and Ryzen desktop CPUs met or even exceeded expectations, realizing comparable performance and IPC to Broadwell and providing Intel with real competition in the X86 space for the first time in years. I am increasingly convinced by CEO Lisa Su’s efforts to turn around the company from the dire straits it was in until the launch of Zen.

AMD’s new Vega GPU architecture has been especially interesting to follow in recent months. I will caveat this article by saying I’m not very familiar with desktop parts, especially GPUs, so I don’t really know much beyond the basics.

What I don’t think most people know, though, is that GPUs are process-constrained. Vega is fabbed on GlobalFoundries’ 14LPP process, which is licensed from Samsung Foundry. TSMC’s 16FF+ was a little better than 14LPP in terms of power and performance, though it’s at least possible process maturity may have closed some of the gap over time. Quite how so many people expected Vega 10 to outperform NVIDIA’s GP104 GPU escapes me, then, given that the two GPUs are fabbed on very comparable processes. (HBM2 memory should make a difference, though, on paper.) I think many people simply assumed that if Vega came out later than NVIDIA’s Pascal, then it must be better.

If you are not familiar with the current state of the PC GPU market, NVIDIA has had a significant efficiency advantage since the introduction of its Maxwell architecture in 2014. It was later revealed that NVIDIA had adopted a tile-based rasterizer, which played a major though not exclusive role in eeking out this efficiency advantage.

Beyond that, it was apparent once AMD announced the TBPs (typical board power ratings) for the first Vega cards that the architecture is fairly terrible on power efficiency. This is not good, because power efficiency is pretty much the most important metric for any IC. To speculate on the reasons behind it at this point would be wild guessing, but it does appear that some things went wrong.

Speaking from experience in the mobile space, I’ve seen vendors who are uncompetitive to some degree on efficiency often boost performance to match the competition on benchmarks, by operating their silicon at more inefficient points in the performance/watt curve. That said, Vega’s being able to match Pascal’s performance is not something to be taken for granted either, and is thankfully the case. Vega's clock speeds are also a non-worry.

Software-wise, AMD’s drivers were clearly running very late. Software historically has not been AMD’s strength, though I am optimistic things will be improving from now on. However, one wonders why the drivers and various new features are so delayed.

Everyone knows that Vega was late. While HBM2 yields likely played a role, there’s probably more to it. Someone smart said that AMD did the right thing to delay the products (as opposed to ostensibly doing something stupid).

To me, it looks like AMD probably had enough issues with Vega that it had to rush out a respin. On the one hand, that would clearly not be good. On the other hand, if so, I’m really glad AMD paid to do it and delayed the non-Frontier cards. Respins are really expensive, and in mobile consumers are often not so lucky to get them. That is the extent of my familiarity with these things at least. The situation with Vega is not the end of the world since its performance is still competitive, and Vega will sell out for quite a long time regardless.

For architecture and competitive analysis, I recommend reading AnandTech (and only AnandTech), though of course useful benchmarks are found on many sites. I would also recommend waiting a week or two to see how the AT review gets updated, because it's impossible to actually analyze much of anything before a review embargo.

And as much as this will probably pain gamers to hear, I consider Vega’s performance on deep learning operations to be much more important than its gaming credentials. There is an inordinate amount of money at stake if AMD can manage to move the needle with Radeon Instinct and HIP against NVIDIA’s domination in deep learning.

A2DP and HFP were switched over to BLEA as of iOS 9

A former Apple engineer has shared that Apple switched A2DP and HFP over to its own Bluetooth LE audio standard in iOS 9. This blew my mind.

For background, here are some of the basics. There are two “Bluetooths”: Classic and Low Energy (LE). The former is the streaming standard that everyone knows through wireless headsets and speakers, while the latter is basically what every modern peripheral device or hardware accessory, such as a smartwatch, uses to transmit data.

LE is also called Bluetooth Smart. LE is bursty and lower power (though not necessarily inherently more efficient), and was designed to enable devices running on coin cell batteries. You can do crazy things like stream video over it, though, if you so desire. (Don't do that.)

I’ve been vaguely keeping track of progress on BLE audio for a few years. I knew that the Bluetooth SIG was working on an LE audio standard, but am amazed that Apple secretly deployed its own in 2015. But it’s not magic, and is still based on LE. “Configuring the HAs is performed through LE services & characteristics, but the audio streaming channel is secret sauce.”

Bluetooth LEA, as Apple calls it, is not used by the AirPods. I’m not sure why, but it may simply be because LEA’s quality is still inferior to Classic audio streaming. Streaming audio is inherently difficult because of LE’s lower duty cycle, which is what makes LE more efficient in general.

Pairing is the same as for the AirPods, using standard LE protocols, though there may be specific codec features that Apple depends on. To emphasize, this is all still built on top of standard Bluetooth. And I believe the SIG is working on a similar pairing UX feature. (Keep in mind that pairing is not required with LE as it is with Classic. Otherwise, say, Bluetooth beacons wouldn’t exist.)



I frequently see people complaining that “Bluetooth sucks” or “Bluetooth is always supposed to get better next year.” Before they were announced, for some reason people even wondered if Apple was going to replace “Bluetooth” for its AirPods. The problem is that people are almost always thinking of the wrong Bluetooth.

I won’t fully explain it here, but basically Classic and LE are different radios. To oversimplify: you can think of Bluetooth 4.0 and later as a completely different spec than 3.0 and earlier. For example, Bluetooth 5 has absolutely nothing to do with the Bluetooth that people normally think of (Classic).


* Thanks to Brendan Sharks for suggesting a correction to the article title.

ARM's brand refresh

I can't think of any semiconductor companies with well-designed logos or wordmarks, but at least this one is better than the old one?

I will definitely never get used to writing "Arm."

SoC suicide

This isn’t really a fix. Sky-high voltages + thermal stress = it’s dead, Jim.

Worth noting: AnandTech got a lot of grief when it didn’t recommend the Nexus 6P or any other Snapdragon 810 or 808 device.

The HDR iPhone 8

I want to write about what should be the highlight feature of the iPhone 8: its HDR display...

This article is available for subscribers on Patreon.

"The New Firefox and Ridiculous Numbers of Tabs"

I’m going to switch to Firefox for a while to try this out.

Even though Firefox is not my main browser, its “Don't load tabs until selected” option has always been my favorite browser feature. The number of tabs I want to load on first launch is exactly one. In an ideal world, the resource overhead of tabs you’re not currently looking at should be as close to zero as possible.

Why you shouldn’t use someone else’s TV calibration settings

I think you will be thoroughly persuaded by this article.

In short, individual display variance is too significant, and you will probably make things worse. If you want to individually calibrate your TV, don't do it yourself, and certainly not by eye. Have a professional do it.

If you want to learn about TVs and home theater equipment, I recommend following Chris Heinonen and reading his articles. Note that I am only recommending him, specifically.

The iOS 11 redesign

Previously I wrote that iOS should be redesigned for OLED. After seeing iOS 11 debut at WWDC and thinking further, though, I realized Apple might go farther than I originally believed...

This article is available for subscribers on Patreon.