[HN Gopher] Ask HN: Is Apple's R1 a Discrete GPU?
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Ask HN: Is Apple's R1 a Discrete GPU?
I think the R1 in Apple's Vision Pro is a discrete GPU, which would
be significant since it would be the first time Apple has shipped a
discrete GPU of their own design and could be an indicator that
discrete GPUs in Macs are imminent. But I'm asking here because I
haven't been able to find any knowledgeable coverage or speculation
about what the R1 chip actually is. The confirmed details of the
R1 chip are scant: - It does a lot of image processing and sensor
data integration: "the brand-new R1 chip processes input from 12
cameras, five sensors, and six microphones to ensure that content
feels like it is appearing right in front of the user's eyes, in
real time. R1 streams new images to the displays within 12
milliseconds"[0] - It has substantial memory bandwidth: "256GB/s
memory bandwidth"[1] - It uses special, high bandwidth memory: "To
support R1's high-speed processing, SK hynix has developed the
custom 1-gigabit DRAM. The new DRAM is known to have increased the
number of input and output pins by eightfold to minimize delays.
Such chips are also called Low Latency Wide IO. According to
experts, the new chip also appears to have been designed using a
special packaging method - Fan-Out Wafer Level Packaging - to be
attached to the R1 chipset as a single unit [...]"[2] - This is
subjective, but: Apple shows it as being roughly the same size as
the M2 processor in the Vision Pro marketing[3], indicating it's a
peer to the M2. Now, that may mean nothing, but based on my
experience with Apple kremlinology they are not arbitrary about
stuff like that. So I see all this and get major GPU vibes. But
I'm just some guy on a the internet, so what do I know? 0:
https://www.macrumors.com/2023/06/05/apple-reveals-vision-pro-
headset/ 1: https://www.apple.com/apple-vision-pro/specs/ 2:
https://9to5mac.com/2023/07/11/vision-pro-performance/ 3:
https://www.apple.com/apple-vision-pro/
Author : toasterlovin
Score : 33 points
Date : 2024-01-22 19:30 UTC (3 hours ago)
| rowanG077 wrote:
| I doubt it's a discrete GPU. It doesn't make sense to split a GPU
| and CPU in such a tiny device. Especially with the gains you can
| get with completely shared memory. I think it's much more likely
| to be a SoC with dsp tiles for the sensors and a huge GPU block
| and standard apple p and e cores.
| rmorey wrote:
| I'm very interested in it as well, I think we can mostly just
| speculate. I don't think it's a GPU, I think it's an independent
| SOC running some sort of real-time OS
| (https://en.wikipedia.org/wiki/Real-time_operating_system) I
| suppose it would necessarily have GPU cores in it to do image
| processing, but I don't think it itself is just a GPU, or gives
| any indication about discrete GPU's coming to the Mac. I think
| this is a very Vision-specific piece of silicon.
|
| Edit: many are saying that is just an Image Signal Processor
| (https://en.wikipedia.org/wiki/Image_processor). I don't think
| that's quite the case because 1) The M-series chips are already
| known to have ISP's packaged into them. and 2) My understanding
| is that the R1's job is to provide continuity of passthrough
| _even in the event of a kernel panic by the M-series chip_. To my
| thinking, this means the R1 chip must have a level of
| independence beyond that of a traditional coprocessor. I think it
| is an entire SOC.
| toasterlovin wrote:
| Alright, here's an idea for you: Vision Pro is shipping with
| the previous generation CPU. What if it was meant to ship
| earlier, but Apple's discrete GPU efforts got delayed? That
| could also explain why the M2 Mac Pro shipped without a
| discrete GPU, which is a glaring omission for that product.
| rmorey wrote:
| I don't think you should hold your breath for discrete GPUs
| coming back any time soon: https://www.owc.com/blog/why-
| the-m2-ultra-mac-pro-doesnt-sup...
| agnokapathetic wrote:
| it's a discrete Image Processing Unit
|
| https://en.wikipedia.org/wiki/Image_processor
| rmorey wrote:
| I don't think this is correct. The M-series chips themselves
| have ISP's in them.
| cududa wrote:
| " Apple shows it as being roughly the same size as the M2
| processor in the Vision Pro marketing[3], indicating it's a peer
| to the M2"
|
| Errr, that's not how this works. The size of them being similar
| means absolutely nothing.
|
| The R1 is a coprocessor, I mean it's basically a big signal
| processor with a decent amount of RAM to handle all the camera
| inputs, and does some GPU like stuff, but isn't a GPU
| toasterlovin wrote:
| The R1 has a lot of memory bandwidth. According to this article
| at Tom's Hardware[0], the M2 has 68 GB/s of memory bandwidth.
| So the R1 has several times that at 256GB/s. Coincidentally (or
| not), that is similar to the discrete Nvidia and AMD GPUs they
| compare the M2 against in that article.
|
| I know discrete GPU comparable memory bandwidth doesn't
| necessarily mean it's discrete GPU or a peer to the M2, but
| there's clearly a lot of _something_ going on. Plus isn 't it
| kinda weird to specifically mention a spec that is applicable
| to programmable devices like CPUs or GPUs on a signal
| processor? Like, who cares?
|
| 0: https://www.tomshardware.com/news/apple-m2-gpu-analysis
| coder543 wrote:
| M1 was 68GB/s (and the article says this too).
|
| M2 was 100GB/s.
| toasterlovin wrote:
| You're right, my mistake.
| snom380 wrote:
| Apple likes mentioning whatever is a competitive advantage.
| M2 has 100GB/s, M2 Pro 200GB/s. They put in the bandwidth
| they think is needed for the purpose. Likewise with the 12
| camera interfaces. It's a safe bet that there's some sort of
| GPU on board but there's zero indication that this is Apples
| first discrete GPU. If anything you would expect such a chip
| to appear first in a desktop product. The R1 is likely
| programmable as well.
| choilive wrote:
| No, likely a dedicated DSP chip to handle the aforementioned 12
| cameras + 5 sensors + 6 mics.
| bhouston wrote:
| I don't think it is a GPU, rather it is probably very similar to
| a DSP/Neural Network chip. Lots of matrix multiplication
| capabilities and streaming data.
|
| https://en.wikipedia.org/wiki/Digital_signal_processor
|
| (Of which https://en.wikipedia.org/wiki/Image_processor are a
| subset of, which someone else in this forum mentions.)
|
| DSPs are similar to GPUs in many respects but they are also
| similar to CPUs in many respects, but it doesn't make them the
| same.
| toasterlovin wrote:
| A few points:
|
| 1. GPUs are good at matrix multiplication!
|
| 2. GPUs are programmable, so you can do software updates, which
| seems like it would be useful if they're also using the R1 to
| do object recognition and other machine vision tasks.
|
| 3. GPUs would be useful in other parts of their product lineup.
| snom380 wrote:
| Lots of processor types are programmable, not just GPUs.
| Apple is well known for making purpose built chips for their
| hardware. Main point is that they reuse the cores across
| different chips. A chip with 12 camera interfaces doesn't
| sound like a general purpose GPU to me.
| polyomino wrote:
| It's basically Apple's version of Microsoft's Holographic
| Processing Unit
| CharlesW wrote:
| The R1 is an SPU (Sensor Processing Unit) which works in concert
| with the M2's integrated GPU (the R1 being the innie, and the M2
| being the outie). It is doing an enormous amount of image signal
| processing, which seems to explain the 256GB/s memory bandwidth.
|
| https://techcrunch.com/2023/06/05/apple-r1-chip-apple-vision...:
| _" The specialized chip was designed specifically for the
| challenging task of real-time sensor processing, taking the input
| from 12 cameras, five sensors (including a lidar sensor!) and six
| microphones. The company claims it can process the sensor data
| within 12 milliseconds -- eight times faster than the blink of an
| eye -- and says this will dramatically reduce the motion sickness
| plaguing many other AR/VR systems."_
| wtallis wrote:
| A 1 Gigabit DRAM chip sounds _far_ smaller than anything that 's
| been used with GPUs in a very long time. That's a capacity from
| 15 years ago.
| nicolas_17 wrote:
| Maybe instead of speculating based on Apple's marketing and based
| on articles from other people speculating, we can make some
| guesses from actual data.
|
| Here's an obviously-incomplete list of source files part of the
| R1 firmware, probably referenced from asserts or other logging
| messages, thus present as strings in the firmware binary:
|
| https://transfer.archivete.am/inline/Ydfxb/bora.txt
|
| It seems it's handling data from cameras (CImageSensor*), LIDAR
| (SensorMgr/Tof = time of flight?), and display (DCP). I also see
| mentions of accel, gyro, bmi284 (IMU from Bosch?).
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(page generated 2024-01-22 23:01 UTC)