[marcan_42]

The Load Balancer is there because the M1 Max has two independent Neural Engines (unlike the GPU cores, which are load balanced in hardware and the OS sees as a single one even on the Ultra)... but one ANE is inexplicably disabled on all production systems. The M1 Ultra, logically, has four... and only the first in each die is enabled.

I was waiting for the Mac Studio to drop to come to a conclusion, since it's plausible one ANE could've been disabled for power reasons on the laptops... but with both secondary ANEs in each die in the M1 Ultra off, and with no reports of anyone seeing the first ANE being disabled instead (which could mean it's a yield thing), I'm going to go ahead and say there was a silicon bug or other issue that made the second ANE inoperable or problematic, and they just decided to fuse it off and leave it as dead silicon on all M1 Max/Ultra systems.

[bayindirh]

Maybe they want to push one as further as possible before enabling the other, hence seeing the limits and increasing the life of the systems by forcing developers to optimize their code?

Sony pulled a similar trick on their A7 series cameras, and enabled more advanced AF features just with a firmware upgrade. It made the bodies "new" and pushed them at least half a generation forward. It's not the same thing, I know, but it feels similar enough for me.

[AgentOrange1234]

Another possible reason would be that there’s a hardware bug which only occurs when both are enabled. (Not saying this is what’s happening here, but it’s very common to ship partly disabled chips to work around bugs.)

[vatys]

For chips, that's commonly referred to as "binning" as in the sorting machine drops chips into different bins based on a test result.

A big design with many cores, such as CPU or GPU cores, may have manufacturing defects that makes one or more cores bad. Or it may be on one side or another of a tolerance range and not be able to work at higher power or higher frequency. These parts may get "binned" into a lower performance category, with some cores disabled (because a flaw prevents the core from working) or with reduced maximum performance states.

These are still "good" parts, and can be sold at a lower cost with lower performance, while the "better" and "best" parts will pass more tests and be able to have more or all portions of the chip enabled.

So it's not so much to work around a "bug" which might be a common flaw to all part designs, rather to work around manufacturing tolerance and allow more built parts to be useful rather than garbage.

[ghettoimp]

Binning is definitely a possibility. Separately from binning, there are often just features that don't work right and get disabled with "chicken switches" or "feature enable bits."

Any two-ANE design would have a lot of control logic that has to be right, e.g., to manage which work gets sent to which ANE, which cache lines get loaded, etc. It's easy to imagine bugs in this logic which would only show up when both ANEs are enabled. So it's likely that there is a chicken bit that you could use to disable one of the ANEs and run in single-ANE mode.

[brigade]

Manufacturing defects are not hardware bugs.

Binning is irrelevant to hardware bugs.

[vatys]

That's what I'm saying, in response to the previous comment saying this is to work around a bug. Bugs are common to all parts, where defects are unique per part. Binning works around manufacturing defects and turns a yield problem into different grades or SKUs of parts.

[klysm]

That’s a very interesting tactic that I haven’t heard of before - almost the opposite of built in obsolescence?

[bayindirh]

Yes. Actually professional photographic equipment doesn't get obsolete. Lenses are expensive and making them forward and backward compatible makes sure the user stays inside the ecosystem. Also, you want higher end bodies to be dependable, so you don't obsolete them, but supersede them with better capabilities.

I can take my old D70s today and take beautiful photos, even with it's 6MP sensor, however a newer body would be much more flexible.

[giobox]

> Actually professional photographic equipment doesn't get obsolete

> I can take my old D70s today and take beautiful photos, even with it's 6MP sensor

I suspect if you do a wedding shoot with a 6mp interchangeable lens camera, some customers are rightly going to ask questions when you hand over the work... Of course professional photographic equipment gets obsolete - even lens systems get deprecated every 20-30 years too. Newer sensors have vastly more dynamic range than the d70s among other image quality benefits.

I think you argument holds water much more strongly in the context of amateur users, where for sure you can keep getting nice images from old gear for a long time.

[bayindirh]

> I suspect if you do a wedding shoot with a 6mp interchangeable lens camera, some customers are rightly going to ask questions when you hand over the work...

Unless you're printing A3 pages, getting gigantic pictures, or cropping aggressively, D70s can still hold up pretty well [0].

> even lens systems get deprecated every 20-30 years too.

Nikon F mount is being deprecated in favor of Z because of mirrorless geometries, not because the lenses or the designs are inferior (given the geometry constraints). Many people still use their old lenses, or nifty fifties are still produced with stellar sharpness levels. I'm not entering into "N" or "L" category of lenses of their respective mounts. Not all of them are post 2000 designs, or redesigns, and they produce extremely good images.

> Newer sensors have vastly more dynamic range than the d70s among other image quality benefits.

As a user of both D70s and A7III I can say that, if there's good enough light (e.g day), one can take pretty nice pictures with a D70s, even today. Yes, it dies pretty fast when light goes low, or it can't focus as fast, or can't take single shot (almost) HDR images (A7III can do that honestly, and that's insane [4]), but unless you're chasing something moving, older cameras are not that bad. [1][2][3]

> I think you argument holds water much more strongly in the context of amateur users, where for sure you can keep getting nice images from old gear for a long time.

Higher end, action oriented professional cameras are not actually built with resolution in mind, especially at the top end. All of the action DSLRs and mirrorless cameras up to a certain point are designed with speed and focus in mind. You can't see A7R or Fuji GFX series in weddings or in stadiums. You'll see A9s, Canon 1D or Nikon D1 series cameras. They're built to be fast. Not high res.

A wedding is more forgiving, but again a high MP camera is not preferred since it's more prone to vibration blurring.

[0]: https://www.youtube.com/watch?v=ku3lT8MjyFM

[1]: https://www.flickr.com/photos/zerocoder/41901384135/in/album...

[2]: https://www.flickr.com/photos/zerocoder/28459579257/in/album...

[3]: https://www.flickr.com/photos/zerocoder/39910477633/in/album...

[4]: https://www.flickr.com/photos/zerocoder/33984196648/in/album...

[inferiorhuman]

No.

> Unless you're printing A3 pages, getting gigantic pictures, or cropping aggressively, D70s can still hold up pretty well

You even qualified that later with "if there's good enough light" and "unless you're chasing something moving". No, a D70 won't work well for wedding photography. Yes, people shot weddings with much slower film. They don't anymore because, like the D70, slow film is obsolete. People shot weddings with manual focus lenses too and the D70 is awful for MF lenses from the tiny viewfinder to the lack of support for non-CPU lenses. When the D70 was a current product some people did (make no mistake the D70 was never marketed as a pro body) simply because the D70 was on par with its contemporaries.

> Nikon F mount is being deprecated in favor of Z because of mirrorless geometries

Even within the scope of the F mount the D70 is obsolete — it's incompatible with new E and AF-P lenses.

> A wedding is more forgiving

Wedding photography is about the most technically challenging, least forgiving (low light, constant motion, spontaneous behavior) type of photography out there. The point you were responding to still stands – older digital photographic equipment is obsolete in a professional context while having some utility for hobbyists. Nobody's taking a D1 out to shoot sports these days. In fact most people didn't when it was new because Nikon's autofocus was so far behind Canon's.

[therein]

A7 SII has continuous autofocus now via a firmware update? That would be very exciting to me.

[bayindirh]

I was talking about A7III. Since I don't have the A7SII, I don't follow its firmware updates. A7III got Animal Eye-AF and much better tracking via a firmware upgrade.

[IshKebab]

My guess would be either a power consumption issue - with both ANEs enabled you could get voltage droops below the acceptable limit. Or it requires software support that they haven't implemented yet. Software always takes waaaay longer than hardware people expect.

[marcan_42]

They sold the chips as having only on me ANE, and software support is there since it's used in the M1 Ultra...

[erwincoumans]

That is interesting, do you have any references / articles that describe that some ANE's are disabled?

Could it be overheating if the ANE's are not used the right way?

[Jcowell]

Probably not but he’s the one the highest divers into the M1 Chip due to his Linux Project so he’s probably the reputable source. Any article written would probably be referencing him.

[erwincoumans]

Ah, delightful to have a/the master behind Asahi development/reverse engineering efforts here!

[bschwindHN]

Delightful to see the creator of Bullet Physics here in the comments too!

[dannyw]

It's just an yields thing I bet; particularly given the relative lack of usage of Neural Engine. If Apple engineers realize that, disabling half the Neural Engines makes no user-visible difference and improves yields by ~1% (hence decreasing silicon costs by ~1%), that's an easy hundreds of millions in saved wafers.

[ricardobeat]

Doesn’t the fact that it’s always the first chip that gets disabled disprove that theory? If it was to improve yield you’d see the other one being disabled at least some of the time.

[fredoralive]

It probably depends on the chip yield, and the sample size of whatever survey was used for the assertion it was always the second engine disabled.

It would be reasonable to assume that if both engines work, then the second is always the one to be disabled. Therefore to have the second enabled you'd need to find one where the first engine has failed, and has no other chip killing faults. Depending on the yield TSMC gets, these could be quite rare, so you'd have to have quite a large survey to find them.

Or as other people have noted, it could be an errata meaning the second core is broken, as this isn't the only possible reason.

[WithinReason]

This would be a reasonable theory, except the neural engine is a small part of the total chip area and thus unlikely to contribute significantly to total chip yield

[marcan_42]

I know it's not the largest sample size, but I did ask twitter and nobody found one with ane1 enabled, it's always ane0.

[runnerup]

> it's plausible one ANE could've been disabled for power reasons on the laptops

The linked posting notes that they were able to get the ANE to draw 49 mW. Is this such a significant amount of power that its worth permanently disabling for laptop power draw? Or is there likely much more power being used elsewhere to support ANE in addition to the 49 mW that can be measured directly?

[grishka]

Is the second ANE disabled in hardware or is it possible to reenable it through software somehow?

[marcan_42]

It's disabled and locked in boot firmware, and the firmware is signed.

[unicornfinder]

Which implies that, at least theoretically, that Apple could enable the other neural engine at a later date (not that they would).

[exikyut]

Just make sure there are no SkyNet singularities hiding inside first.

...maybe Apple disabled it for a reason, y'know?

[thisNeeds2BeSad]

Maybe protect against lawsuits from a chip patch slowdown after architectural migations are necessary, because of inherent design speed optimization safety flaws?

[greggsy]

Perhaps they’ll allow you to use it through subscription, like z/OS mainframes locking down cores?