3 ms·

Is there any actual evidence that this marginally lower latency makes any real life difference? And why would the laptops suddenly ship with a variety of modul

Is there any actual evidence that this marginally lower latency makes any real life difference? And why would the laptops suddenly ship with a variety of modules if they're replaceable? You can still ship it with the same modules in every laptop and get those benefits. And if someone upgrades it, that's still an improvement over no upgrade path, so this makes no sense to me.

kube-system 4y ago
> Is there any actual evidence that this marginally lower latency makes any real life difference? Yes, compare the specs of DDR4 and DDR5 to LPDDR4X and LPDDR5X. The latter are significantly higher performance. This is also the reason that Dell recently introduced CAMM memory modules -- it is an attempt to address the packaging bottleneck that is limiting the speed of DIMMs currently. The amount of time that it takes a signal to go down a wire has been relevant for DRAM for a while now. If you look at the traces on the board of any relatively modern computer, you'll see some that take circuitous routes, for the purpose of having the signals arrive at the CPU at the same time. You can see this even on relatively low performance devices like a Raspberry Pi. https://www.cnx-software.com/wp-content/uploads/2019/06/Raspberry-Pi-4-Model-B-Large.jpg https://www.cnx-software.com/wp-content/uploads/2019/06/Rasp...
- wtallis 4y ago
  > If you look at the traces on the board of any relatively modern computer, you'll see some that take circuitous routes, for the purpose of having the signals arrive at the CPU at the same time. Having all the signals arrive at the same time isn't the same thing as having the signals arrive soon.
  - kube-system 4y ago
    Correct. My point was to simply illustrate that the fractions of time involved are small enough that trace length matters.
Wowfunhappy 4y ago
High bandwidth, low latency unified memory is a central component of the M series architecture and a key reason those chips perform so well at their power profile. I'm not sure what "evidence" I could provide that would convince you since we don't have high latency Apple chips to benchmark against. However, there's a reason VRAM is soldered onto GPUs.

kube-system 4y ago

> Is there any actual evidence that this marginally lower latency makes any real life difference? Yes, compare the specs of DDR4 and DDR5 to LPDDR4X and LPDDR5X. The latter are significantly higher performance. This is also the reason that Dell recently introduced CAMM memory modules -- it is an attempt to address the packaging bottleneck that is limiting the speed of DIMMs currently. The amount of time that it takes a signal to go down a wire has been relevant for DRAM for a while now. If you look at the traces on the board of any relatively modern computer, you'll see some that take circuitous routes, for the purpose of having the signals arrive at the CPU at the same time. You can see this even on relatively low performance devices like a Raspberry Pi. https://www.cnx-software.com/wp-content/uploads/2019/06/Raspberry-Pi-4-Model-B-Large.jpg https://www.cnx-software.com/wp-content/uploads/2019/06/Rasp...

wtallis 4y ago
> If you look at the traces on the board of any relatively modern computer, you'll see some that take circuitous routes, for the purpose of having the signals arrive at the CPU at the same time. Having all the signals arrive at the same time isn't the same thing as having the signals arrive soon.
- kube-system 4y ago
  Correct. My point was to simply illustrate that the fractions of time involved are small enough that trace length matters.

Wowfunhappy 4y ago

High bandwidth, low latency unified memory is a central component of the M series architecture and a key reason those chips perform so well at their power profile. I'm not sure what "evidence" I could provide that would convince you since we don't have high latency Apple chips to benchmark against. However, there's a reason VRAM is soldered onto GPUs.