Comment by nordsieck | Hacker News Reader

Comment by nordsieck | Hacker News Reader

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> I saw a previous HN comment about this being due to memory bandwidth and cache latency, but I can't seem to substantiate that comment.

I don't know if Apple has released any stats, but it makes a certain amount of sense. The technical reason to put memory and the CPU/GPU on a single package is to decrease memory latency (and possibly boost operating frequency). There's probably also the option to have a really wide memory bus.

Of course, a nice side benefit for Apple is that people can no longer buy 3rd part ram at market rates.

That being said...

> My M1 MacBook is significantly "faster" than my previous Intel 16", even though the per-core performance are roughly similar in CPU benchmarks (small advantage to M1).

The thing about benchmarks is, they're sometimes particular to a specific application, and even data sets. So M1 can be largely tied with an Intel chip across a broad range of benchmarks (e.g. Geekbench), but it can also be a lot faster on your specific workloads.

> The technical reason to put memory and the CPU/GPU on a single package is to decrease memory latency (and possibly boost operating frequency).

You've got that backwards, I think. Putting memory on package, or even just soldered on the PCB nearby rather than in removable DIMMs primarily helps hit higher frequencies or lower power at similar frequencies (GPUs and smartphones provide a wealth of examples). There's little or no impact on latency, because most DRAM latency occurs within the DRAM dies or inside the CPU's cache hierarchy rather than on the link between the CPU and DRAM.

Seems to be both. One big advantage which is not visible on the M1 (which has a 128 bit wide memory), is the M1 pro, max, and ultra have 2x, 4x, and 8X the memory bandwidth. Something that's much harder on the x86-64 size, and (AFAIK) impossible on x86-64 laptop.

The latency does seem improved in the last level cache and main memory, at least compared to AMD's Ryzen 5000 series. Sadly looks like Anandtech has lost the people who did the deep dives and I can't find similar latency numbers for cache and ram for the Ryzen 7000 series.

Apple's power efficiency allows for a 512 bit wide memory system in a laptop, 4 times any x86-64 laptop. I do hope that AMD or Intel ups their game and allows for more aggressive memory systems on laptops. Only similar design I know of is the Xbox series X and PS5, which both use AMD chips with improved memory systems to keep from bottlenecking the iGPU.

I think a big reason for Anandtech losing the deep dive expertise is that the founder of Anandtech, Anand Lal Shimpi, was hired by… Apple! That was a while ago (2014), but that sort of knowledge isn't easy to find I imagine.

Many of the heavy hitters who used to test and write for Anandtech seem to have left too :(

Agreed, sadly he's not the only expert to leave.

The 16" MBP is competitive, on wall power, for short periods of time before it's thermally throttled (even while the fans scream). Which usually means single core benchmarks.

The 16" MBP, at least mine, thermally throttles at the drop of a hat. Teams video conf, backups, virus scan, even small builds, etc.

The M1 in comparison is quiet, cool, not sure I've heard the fan going. So sure the performance is similar, the perf/watt is not.

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