By: Doug S (foo.delete@this.bar.bar), November 17, 2020 1:21 pm
Room: Moderated Discussions
Dummond D. Slow (mental.delete@this.protozoa.us) on November 17, 2020 11:18 am wrote:
> Which also tells you where the biggest threat from Apple is. It pretty much caught
> up with state of the art x86's single core performance AND has process advantage.
> It could shoot ahead in performance in two areas if it chose to:
> 1) SMT as discussed. Not having SMT leaves massive multithread performance
> gains (end energy efficiency gains, more importantly) on the table.
Does that really matter all that much for desktop use? Maybe it matters for the Mac Pro, but that's just not a big enough piece of the overall Mac market (let alone the overall 'Apple SoC' market) for them to add SMT, IMHO.
Now if Apple was going build their own servers (for iCloud, Siri, maybe Search if antitrust issues force Google to quit paying Apple for being the default search in Safari) then adding SMT would make more sense since they can amortize the extra design/verification work across more units.
> 2) AMD and to a bit less degree Intel squeeze the single core frequency of the core during single-thread boosting,
> with very high voltage and advanced power management so that they can pretty much run it as fast as the silicon
> allows and as high or even higher than manual overclocking can reach. This is why the power consumption in
> their single core turbo boosts is so high (it does dial way lower during all-core load clocks).
> Apple seems to only have simple turbo that drops clocks a bit on multicore load, but it is only a small difference.
> That implies Apple could extract a lot of frequency if it went as advanced on power management and aggressive
> on turbo as AMD does. I don't know how high it could go - the low power it exhibits suggest there is a lot
> of headroom, but perhaps the wide engine just couldin't handle much more due to timing even if it doesn't
> have high power output. But some potential Apple has not tapped yet is likely there.
I agree that Apple clearly has some room to increase performance with binning/turbo, but again how much sense does that effort make for their market? It would be nice for those of us watching on the sidelines and wanting to see a real performance war, but in reality Apple is competing with the last version of their own products not with what you can buy from Dell, and the M1 is already faster for ST than any x86 Mac so they don't NEED to do this. Maybe they will explore it in the M2 or M3, I hope they do, but I wouldn't be surprised if they feel their design effort is better spent elsewhere.
Heck, Apple could get faster by simply not designing for low power. According to TSMC using HPC cells gets you a 10% boost, and other tricks you can do when power draw is less important can get 10% more. An M1+ clocked at 3.8 GHz would be one hell of a beast, though if it used 2x more power per core it would really only be appropriate for a Mac Pro - every other Mac is quite cooling constrained due to the form factor. Sure, they COULD pay for a separate tapeout when the Mac Pro starts at $5K, but they'd only be able to fit half as many cores at the same power budget. So they probably will use low power transistors there despite the potential for faster ST performance, EVEN if they do a separate design for the Mac Pro (i.e. based on being able to leverage it for internal server use also)
> Which also tells you where the biggest threat from Apple is. It pretty much caught
> up with state of the art x86's single core performance AND has process advantage.
> It could shoot ahead in performance in two areas if it chose to:
> 1) SMT as discussed. Not having SMT leaves massive multithread performance
> gains (end energy efficiency gains, more importantly) on the table.
Does that really matter all that much for desktop use? Maybe it matters for the Mac Pro, but that's just not a big enough piece of the overall Mac market (let alone the overall 'Apple SoC' market) for them to add SMT, IMHO.
Now if Apple was going build their own servers (for iCloud, Siri, maybe Search if antitrust issues force Google to quit paying Apple for being the default search in Safari) then adding SMT would make more sense since they can amortize the extra design/verification work across more units.
> 2) AMD and to a bit less degree Intel squeeze the single core frequency of the core during single-thread boosting,
> with very high voltage and advanced power management so that they can pretty much run it as fast as the silicon
> allows and as high or even higher than manual overclocking can reach. This is why the power consumption in
> their single core turbo boosts is so high (it does dial way lower during all-core load clocks).
> Apple seems to only have simple turbo that drops clocks a bit on multicore load, but it is only a small difference.
> That implies Apple could extract a lot of frequency if it went as advanced on power management and aggressive
> on turbo as AMD does. I don't know how high it could go - the low power it exhibits suggest there is a lot
> of headroom, but perhaps the wide engine just couldin't handle much more due to timing even if it doesn't
> have high power output. But some potential Apple has not tapped yet is likely there.
I agree that Apple clearly has some room to increase performance with binning/turbo, but again how much sense does that effort make for their market? It would be nice for those of us watching on the sidelines and wanting to see a real performance war, but in reality Apple is competing with the last version of their own products not with what you can buy from Dell, and the M1 is already faster for ST than any x86 Mac so they don't NEED to do this. Maybe they will explore it in the M2 or M3, I hope they do, but I wouldn't be surprised if they feel their design effort is better spent elsewhere.
Heck, Apple could get faster by simply not designing for low power. According to TSMC using HPC cells gets you a 10% boost, and other tricks you can do when power draw is less important can get 10% more. An M1+ clocked at 3.8 GHz would be one hell of a beast, though if it used 2x more power per core it would really only be appropriate for a Mac Pro - every other Mac is quite cooling constrained due to the form factor. Sure, they COULD pay for a separate tapeout when the Mac Pro starts at $5K, but they'd only be able to fit half as many cores at the same power budget. So they probably will use low power transistors there despite the potential for faster ST performance, EVEN if they do a separate design for the Mac Pro (i.e. based on being able to leverage it for internal server use also)