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Astounding! Whereas I just got a laptop from work, a Dell Inspiron that dies if I leave it in my backpack over the weekend. How has x86-64 managed to go so wro

by wincy 5y ago

Astounding! Whereas I just got a laptop from work, a Dell Inspiron that dies if I leave it in my backpack over the weekend. How has x86-64 managed to go so wrong for mobile devices and power usage? Is it really purely because of backwards compatibility cruft, or just goals that aren’t aligned with low power usage in idle?

marcan_42 5y ago
I think it's a bit of both, plus corporate culture at Intel/AMD not getting it (especially Intel) and then OEMs screwing things up even more with all the hardware around the CPU proper. E.g. I have an x86 laptop where the SSD gets warm in standby; clearly that's not going to do any good for standby battery life. Since Apple controls the whole stack, they can make sure all this stuff is done properly from top to bottom.
- wtallis 5y ago
  > E.g. I have an x86 laptop where the SSD gets warm in standby NVMe power management is frequently this hilariously bad. There's no real coordination between the NVMe and PCIe specs on power management features, so you can end up with drives that have undeclared dependencies where you aren't supposed to try to use a certain NVMe power state unless you also have a certain level of PCIe link state power management enabled. If you break the drive's assumptions, it'll usually freak out and turn off all power management, leading to power consumption often higher than when the drive's in its active power state but not doing anything. And Microsoft's NVMe driver avoids using a lot of the power management functionality that drives implement, so laptop OEMs and drive vendors have little incentive to clean up the mess (not that they're any good at ensuring the power management techniques used by Windows aren't broken).
  - marcan_42 5y ago
    This one is mSATA :-)
    - wtallis 5y ago
      Ouch. That's even more ridiculous, given how few variables are involved in SATA power management.
- olliej 5y ago
  Don’t forget the OEM then trying to make money by adding bucketloads of terrible software and “helpful” tools that screw with power even more. I suspect that hurts windows’ power usage no matter what the poor engineers at MS want :-/
bestouff 5y ago
Your Dell dies if you leave it in your backpack over the weekend ? I contest that claim. My XPS i9 dies if I left it in my backpack overnight ! I can't wait to have Linux properly running on an M1 Pro, so I can justify buying one.
- deleted 5y ago
  [deleted]
paulryanrogers 5y ago
How many x86-64 laptops are using 5nm CPUs or built vertically integrated by the OS vendor?
- acdha 5y ago
  > How many x86-64 laptops are using 5nm CPUs Can you quantify exactly how much you expect 5nm to buy versus 7nm and why? We're seeing wins which are much larger than a single process shrink could explain — Intel's been lost in the woods for years but AMD has generally been doing a quite respectable job but the story isn't night-and-day better there, either. > … or built vertically integrated by the OS vendor? I believe this is rather the point: x86 has some overhead baked in due to compatibility reasons but that's nowhere near enough to explain the differences we're seeing. I think what we're seeing is the fact that Microsoft, {Intel,AMD}, and the ISVs have not done a great job coordinating because no one party owns power efficiency and most of the big wins require coordination between companies who are prone to suggesting the hard work be paid for by someone else. If, say, PC reviews lead with performance/watt metrics that might change quickly.
leetcrew 5y ago
as someone else said, apple is a node ahead of AMD this round. that won't necessarily continue; they don't own TSMC. I expect the gap will close somewhat if they both launch their next gen parts on the same node. > goals that aren’t aligned with low power usage in idle? some of this too. intel and AMD architectures need to work for laptop, desktop, and server markets. that's a pretty wide optimization target. on the other hand, apple's m1 targets ipads, laptops, and laptops in a desktop chassis. they have the opportunity to focus much more intensely on the low end of the perf/W curve.
- microtonal 5y ago
  some of this too. intel and AMD architectures need to work for laptop, desktop, and server markets. that's a pretty wide optimization target. And yet, my previous passively-cooled MacBook Air M1 was faster than a workstation-class Ryzen 3700X with a large active cooling block. And my MacBook Pro with an M1 Pro is somewhere between a 5850X and 5900X performance-wise. Both have 105W TDP and require again a large active cooling block, while the MacBook's fans barely spin up. Then, thanks to the AMX matrix multiplication unit, the M1 Pro has almost 2x sgemm throughput of a 5900X (2254 vs 1390 GFLOP/s). The M1 goes toe to toe with the 5900X (1217 GFLOP/s) while only using 7.5W. Sure, of the performance per watt can be explained by a better process node or focus on portable devices. However, the fact that M1/M1 Pro are as fast as high-end Ryzen workstation CPUs at a small fraction of the TDP, shows that Apple also put some of the finest engineering work in the M1.
  - hajile 5y ago
    A13 is made on the same 7nm TSMC process as AMD is using and is still much more efficient. Node size isn't a very good argument at this point.
    - acomjean 5y ago
      According to AMD you get >1.25 performance at 1/2 the power usage when chips go from 7nm to 5nm. So when x86 gets to 5nm the difference in performance might be fairly negligible. Its not everything but its certainly not nothing. https://www.tomshardware.com/news/amd-unveils-zen-4-cpu-roadmap-96-core-5nm-genoa-128-core-begamo https://www.tomshardware.com/news/amd-unveils-zen-4-cpu-road...
kcb 5y ago
Work laptops are frequently infected with malware of all sorts.
- wincy 5y ago
  Hah yes a fellow engineer showed me a “trick” the other day. They don’t want you trying to close their corporate malware so if you open task manager it’ll throttle down its resource usage to keep you from noticing how it’s slowing everything down. So if you just run task manager in the background the computer will run faster.

by wincy 5y ago

marcan_42 5y ago

I think it's a bit of both, plus corporate culture at Intel/AMD not getting it (especially Intel) and then OEMs screwing things up even more with all the hardware around the CPU proper. E.g. I have an x86 laptop where the SSD gets warm in standby; clearly that's not going to do any good for standby battery life. Since Apple controls the whole stack, they can make sure all this stuff is done properly from top to bottom.

wtallis 5y ago
> E.g. I have an x86 laptop where the SSD gets warm in standby NVMe power management is frequently this hilariously bad. There's no real coordination between the NVMe and PCIe specs on power management features, so you can end up with drives that have undeclared dependencies where you aren't supposed to try to use a certain NVMe power state unless you also have a certain level of PCIe link state power management enabled. If you break the drive's assumptions, it'll usually freak out and turn off all power management, leading to power consumption often higher than when the drive's in its active power state but not doing anything. And Microsoft's NVMe driver avoids using a lot of the power management functionality that drives implement, so laptop OEMs and drive vendors have little incentive to clean up the mess (not that they're any good at ensuring the power management techniques used by Windows aren't broken).
- marcan_42 5y ago
  This one is mSATA :-)
  - wtallis 5y ago
    Ouch. That's even more ridiculous, given how few variables are involved in SATA power management.
olliej 5y ago
Don’t forget the OEM then trying to make money by adding bucketloads of terrible software and “helpful” tools that screw with power even more. I suspect that hurts windows’ power usage no matter what the poor engineers at MS want :-/

bestouff 5y ago

Your Dell dies if you leave it in your backpack over the weekend ? I contest that claim. My XPS i9 dies if I left it in my backpack overnight ! I can't wait to have Linux properly running on an M1 Pro, so I can justify buying one.

deleted 5y ago
[deleted]

paulryanrogers 5y ago

How many x86-64 laptops are using 5nm CPUs or built vertically integrated by the OS vendor?

acdha 5y ago
> How many x86-64 laptops are using 5nm CPUs Can you quantify exactly how much you expect 5nm to buy versus 7nm and why? We're seeing wins which are much larger than a single process shrink could explain — Intel's been lost in the woods for years but AMD has generally been doing a quite respectable job but the story isn't night-and-day better there, either. > … or built vertically integrated by the OS vendor? I believe this is rather the point: x86 has some overhead baked in due to compatibility reasons but that's nowhere near enough to explain the differences we're seeing. I think what we're seeing is the fact that Microsoft, {Intel,AMD}, and the ISVs have not done a great job coordinating because no one party owns power efficiency and most of the big wins require coordination between companies who are prone to suggesting the hard work be paid for by someone else. If, say, PC reviews lead with performance/watt metrics that might change quickly.

leetcrew 5y ago

as someone else said, apple is a node ahead of AMD this round. that won't necessarily continue; they don't own TSMC. I expect the gap will close somewhat if they both launch their next gen parts on the same node. > goals that aren’t aligned with low power usage in idle? some of this too. intel and AMD architectures need to work for laptop, desktop, and server markets. that's a pretty wide optimization target. on the other hand, apple's m1 targets ipads, laptops, and laptops in a desktop chassis. they have the opportunity to focus much more intensely on the low end of the perf/W curve.

microtonal 5y ago
some of this too. intel and AMD architectures need to work for laptop, desktop, and server markets. that's a pretty wide optimization target. And yet, my previous passively-cooled MacBook Air M1 was faster than a workstation-class Ryzen 3700X with a large active cooling block. And my MacBook Pro with an M1 Pro is somewhere between a 5850X and 5900X performance-wise. Both have 105W TDP and require again a large active cooling block, while the MacBook's fans barely spin up. Then, thanks to the AMX matrix multiplication unit, the M1 Pro has almost 2x sgemm throughput of a 5900X (2254 vs 1390 GFLOP/s). The M1 goes toe to toe with the 5900X (1217 GFLOP/s) while only using 7.5W. Sure, of the performance per watt can be explained by a better process node or focus on portable devices. However, the fact that M1/M1 Pro are as fast as high-end Ryzen workstation CPUs at a small fraction of the TDP, shows that Apple also put some of the finest engineering work in the M1.
- hajile 5y ago
  A13 is made on the same 7nm TSMC process as AMD is using and is still much more efficient. Node size isn't a very good argument at this point.
  - acomjean 5y ago
    According to AMD you get >1.25 performance at 1/2 the power usage when chips go from 7nm to 5nm. So when x86 gets to 5nm the difference in performance might be fairly negligible. Its not everything but its certainly not nothing. https://www.tomshardware.com/news/amd-unveils-zen-4-cpu-roadmap-96-core-5nm-genoa-128-core-begamo https://www.tomshardware.com/news/amd-unveils-zen-4-cpu-road...

kcb 5y ago

Work laptops are frequently infected with malware of all sorts.

wincy 5y ago
Hah yes a fellow engineer showed me a “trick” the other day. They don’t want you trying to close their corporate malware so if you open task manager it’ll throttle down its resource usage to keep you from noticing how it’s slowing everything down. So if you just run task manager in the background the computer will run faster.