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slawejandur95

macrumors member
Original poster
Jul 20, 2020
57
34
With new M1 Macs, we only get two options for the RAM: 8 and 16GB.

My current daily driver is a base model of MBA 2017. With many tabs open, Pages, Preview, etc., it is starting to feel like it's not enough. Next week I'm getting M1 Air with 16GB of RAM (well, 99% sure of that). We all know that the optimization on iPhones and iPads is phenomenal and now I'm debating whether it is worth to spend extra money for something that might not be necessary. Don't you think that 16GB might be "the new 32"? Does anybody have any experience with both 8GB and 16GB models? What's your opinion?
 

robertosh

macrumors 65816
Mar 2, 2011
1,081
897
Switzerland
I think that we should take the first M1 as the entry levels for basic usage and some light pro work. For that I think that 8/16G are enough. In case you have more professional use case, then you will need more ... basically if you need to process dozens of GB of data there is no way that it will fit on 16G...

It’s also true that the ssds are so fast today that the RAM is not as critical, or, better to say, the penalty of not having enough RAM is not as dramatic as it was a couple of years ago.
 

Kraizelburg

macrumors 6502
Nov 10, 2018
437
113
Spain
I was in the same situation and I decided to get the 8GB 512GB disk because later next year we will have the second iteration of M1 for sure so spending a lot in the entry model it seems a bit pointless to me, but this is only my opinion. I also have a powerful linux machine with ryzen so I am covered.

Next year when they release the proper 4 ports MBP I will probably sell this mba.
 

johannnn

macrumors 68020
Nov 20, 2009
2,192
2,289
Sweden
I got the 8GB. It absolutely flies with my casual usage. It absolutely swaps to the SSD, but I never notice it. The machine and the SSD are just so fast.

I could have gotten the 16GB to future-proof it. I'd do it for $100. But $200 is too much. I prefer to just sell it in ~2 years and get the new one.
 

casperes1996

macrumors 604
Jan 26, 2014
7,336
5,295
Horsens, Denmark
It’s also true that the ssds are so fast today that the RAM is not as critical, or, better to say, the penalty of not having enough RAM is not as dramatic as it was a couple of years ago.
Yes and no in a way. While SSDs in these Macs offer tremendous performance rivalling the RAM in way older machine - The bandwidth sits between DDR-200 and DDR-400. Well, there's just also more data flying through the chip and everything has grown hungrier. macOS is intelligent about the use of swap and generally avoids swapping an entire program, but instead just bits and pieces so nothing is really slow to deal with but while the SSDs offer bandwidth between 2 and 3GB/s, the LPDDR4X on the SoC is more in the neighbourhood of ≈56GB/s. And that's just bandwidth, way more crucial to the feel of using the device is latency, where DRAM is in the range of a couple hundred CPU cycles and the SSD is probably well over a thousand cycles though I have no exact figure for M1 where the SoC is also acting as the SSD controller.
That said, both Firestorm and Icestorm also have incredibly wide out-of-order re-order queues to keep themselves busy and schedule reads from memory or I/O and performing other tasks while waiting on the read.

The M1 also would use a little less memory for dedicated hardware DMA operations as it has a shared SoC level memory structure and most chips in the system are consolidated into that single system package so you don't need to keep duplicate copies of data from other devices - Though that is negligible on devices that have previously used iGPUs since there's not much other hardware in there with large independent memory space with consolidation pointers to system RAM. It could reduce RAM requirements of devices with dedicated GPUs somewhat though since normally, most data is kept both in GPU VRAM and in system memory and synchronised at certain points when there needs to be cross-hardware communication. Of course now that system RAM also belongs to the GPU but at least there's a smaller need for more RAM chips.

Though even if macOS is less RAM intensive on M1, there's no reason to believe the slew of Electron apps and others will be. Perhaps they will suffer a smaller hit from reaching swap with fast SSDs and the M1 acting as the controller with perhaps more direct access to the NAND, but I doubt the capacity needs are that much less, if at all, before you do hit swap. And swap is still orders of magnitudes slower, even if that speed penalty is hidden by good OOO reordering.

All in all my personal conclusion is thus:
Look at your workload in Activity Monitor on your current Mac. How much RAM do you have and what colour is the pressure graph? Make your decision based on that.
8 could very well be enough, but you can't change it later, so if you're pushing into the yellow or red with 8GB currently, I would get 16 for the M1 just to not regret it even if it's not felt as hard. And it while it might cost more I also do think the resale value for the future will be slightly higher; Not entirely offsetting the difference, but minimising it somewhat.
Don't buy excessively, but don't expect it to handle memory exactly like iOS - The macOS and iOS memory management systems and how much extra macOS needs to deal with is still a difference between the two platforms and macOS' multi-tasking model does not have the same suspend-stages iOS does. Apps in the background run more actively (iOS apps on the Mac somewhat being in a funky middle stage here since the code paths have the suspend stages and the associated frameworks are there, but the Mac will prefer having them more active even when backgrounded so that they respond immediately if things happen and can give visual cues even when they're not in the foreground, though it can still deep-sleep some aspects of the execution - WWDC talk exists that goes into more detail on that)
 

mikethebigo

macrumors 68020
May 25, 2009
2,277
1,104
Born of the Intel architecture.

We don't know what RAM does on the M1 longer term.
RAM is RAM at the end of the day. Apple Silicon Macs may have better memory management in that they'll be faster to compress memory and swap it due to optimizations, but they aren't magically changing the properties of data sizes.
 
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panerista

macrumors demi-goddess
Oct 20, 2011
12,676
10,510
Austin, TX
RAM is RAM at the end of the day. Apple Silicon Macs may have better memory management in that they'll be faster to compress memory and swap it due to optimizations, but they aren't magically changing the properties of data sizes.
Oversimplified. M1 is using UMA and if the A chips are any indication, when unified with the software environment, RAM is about as unimportant as ever.
 
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mikethebigo

macrumors 68020
May 25, 2009
2,277
1,104
Oversimplified. M1 is using UMA and if the A chips are any indication, when unified with the software environment, RAM is about as unimportant as ever.
What exactly does that mean?

They have been very clear about this. Unified memory means that things don't need to be bussed between CPU and GPU memory, and it means everything in the system can address it faster. It does not mean that a bunch of memory hogging Chrome tabs will suddenly need less room to store data.

iPhones and iPads dealt with memory constraints by aggressively killing background processes. The Mac is fundamentally different as it won't ever do that. It will swap memory instead. And in my (not particularly heavy) use of an 8GB M1 Mac, I built up a 5 GB swap file that I could tell the system was frequently paging to.

This isn't like, you wave your hand and say "unified memory" and that means the fundamentals of memory management suddenly change. That's what is the oversimplification. M1 Macs compress memory, page out to the SSD, and do all the other typical memory management things just like the Intel Macs did. They might be faster at it, but they're still doing it.
 

theluggage

macrumors 604
Jul 29, 2011
7,440
7,249
Born of the Intel architecture.

We don't know what RAM does on the M1 longer term.

Fancy a cuppa?


There's no reason to presume that RAM "goes further" on M1 vs. Intel when running substantially the same software on substantially the same OS. RAM access on the M1 is still vastly faster than moving data to/from SSD. What we do know is that the M1 Macs are all-round faster - by a significant margin - than the Intel macs they replace - but that is a combination of faster/more power efficient CPU, GPU, SSD and better RAM bandwidth measured on tasks and benchmarks which aren't necessarily constrained by RAM in the first place.

An 8GB M1 may be faster than a 16GB 16" MacBook Pro on certain tasks because the faster GPU and SSD count for more than the reduced RAM - but that doesn't generalise to all tasks, especially those that actually rely on having multiple-gigabyte datasets loaded into RAM.

What we may be seeing is that a lot of people have over-estimated how much RAM they need, even on Intel, or were seeing fairly modest speed-ups from extra file caching which are dwarfed by the effects of the faster/more efficient/Metal-and-apple-video-format-optimised SoC. That won't necessarily help in tasks where you genuinely need enough RAM to randomly access a 16GB dataset.

The M1 vs Intel Mac debate is ephemeral anyway - what we'll see sometime next year is how M1 Macs fare against M2/M1x/whatever Macs, possibly with 32GB or more RAM.
 

mikethebigo

macrumors 68020
May 25, 2009
2,277
1,104
Fancy a cuppa?


There's no reason to presume that RAM "goes further" on M1 vs. Intel when running substantially the same software on substantially the same OS. RAM access on the M1 is still vastly faster than moving data to/from SSD. What we do know is that the M1 Macs are all-round faster - by a significant margin - than the Intel macs they replace - but that is a combination of faster/more power efficient CPU, GPU, SSD and better RAM bandwidth measured on tasks and benchmarks which aren't necessarily constrained by RAM in the first place.

An 8GB M1 may be faster than a 16GB 16" MacBook Pro on certain tasks because the faster GPU and SSD count for more than the reduced RAM - but that doesn't generalise to all tasks, especially those that actually rely on having multiple-gigabyte datasets loaded into RAM.

What we may be seeing is that a lot of people have over-estimated how much RAM they need, even on Intel, or were seeing fairly modest speed-ups from extra file caching which are dwarfed by the effects of the faster/more efficient/Metal-and-apple-video-format-optimised SoC. That won't necessarily help in tasks where you genuinely need enough RAM to randomly access a 16GB dataset.

The M1 vs Intel Mac debate is ephemeral anyway - what we'll see sometime next year is how M1 Macs fare against M2/M1x/whatever Macs, possibly with 32GB or more RAM.
Agreed with all of this. It's a combination of factors - people want to like their base model M1 Macs so are looking to justify the 8 GB, many people never needed 16 GB to begin with, and the system is much faster and more efficient with memory management, to the point that you only even notice SSD swap if you're looking for it. Put all those things together and people think it's because the new RAM architecture is somehow special and different compared to "Intel" RAM, when it's ultimately just a faster version of the same.
 

mannyvel

macrumors 65816
Mar 16, 2019
1,375
2,478
Hillsboro, OR
It's been a long time since it was discussed, but you do lose a lot of performance context switching. DMA and no-copy semantics are a way to hack around the performance loss and memory usage inherent in separate mapped address spaces that are considered a requirement for modern operating systems. In fact, the microkernel idea sort of failed because it was too slow, generally speaking. Mach isn't really a microkernel anymore because of that.

It could be that Apple has a new way to handle this with their new memory architecture. The interview on ars about the M1 implies that the UMA is a big part of the new world, and a new and improved MMU/address implementation is definitely part of that. That's the thing that can really only happen if you're vertically integrated; you can design everything. For example, Solaris actually used the sliding window registers on SPARC. That wasn't some random chip feature, and that's not something a generic cpu manufacturer would implement.

X86 has been with us for so long that people forget that there were other ways to do things, and that there are tons of things that x86 didn't do particularly well that were hidden by its ability to clock up. A better algorithm can provide an order of magnitude more performance, and we might be seeing that here. If you can do a couple of those improvements, well, that's a super-big win.

So what does that mean? I'd say get 16gb but watch and see if it's actually being used. I suspect a lot of things about how things work have changed with the m1, but it's too early to tell.
 
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Strangedream

macrumors 6502a
Sep 15, 2019
661
545
London, UK
The only way RAM could be irrelevant is if we had specialized SSD with read/write speeds >= 20 Gbps so 10x faster than current MBA/MBP SSD. They'd also need to keep a partition only for temp information so you don't run out of virtual RAM. These would be pretty expensive.
 

panerista

macrumors demi-goddess
Oct 20, 2011
12,676
10,510
Austin, TX
Agreed with all of this. It's a combination of factors - people want to like their base model M1 Macs so are looking to justify the 8 GB, many people never needed 16 GB to begin with, and the system is much faster and more efficient with memory management, to the point that you only even notice SSD swap if you're looking for it. Put all those things together and people think it's because the new RAM architecture is somehow special and different compared to "Intel" RAM, when it's ultimately just a faster version of the same.
This is just a really ugly FOMO take.
 

LeeW

macrumors 601
Feb 5, 2017
4,121
8,919
Over here
There is a real lack of understanding around RAM in the M1 devices, I saw someone on another forum posting about how great and amazingly speedy their device was with 8GB Ram and it wasn't even causing any issue. I pointed out in their screenshot the 8.4GB Swap file and they just replied, "yes, it's great, Apple can do amazing things"...
 
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mikethebigo

macrumors 68020
May 25, 2009
2,277
1,104
There is a real lack of understanding around RAM in the M1 devices, I saw someone on another forum posting about how great and amazingly speedy their device was with 8GB Ram and it wasn't even causing any issue. I pointed out in their screenshot the 8.4GB Swap file and they just replied, "yes, it's great, Apple can do amazing things"...
Ah yes, the radical new technology of swap memory ?
 

Runs For Fun

macrumors 65816
Nov 6, 2017
1,138
2,601
Yes and no in a way. While SSDs in these Macs offer tremendous performance rivalling the RAM in way older machine - The bandwidth sits between DDR-200 and DDR-400. Well, there's just also more data flying through the chip and everything has grown hungrier. macOS is intelligent about the use of swap and generally avoids swapping an entire program, but instead just bits and pieces so nothing is really slow to deal with but while the SSDs offer bandwidth between 2 and 3GB/s, the LPDDR4X on the SoC is more in the neighbourhood of ≈56GB/s. And that's just bandwidth, way more crucial to the feel of using the device is latency, where DRAM is in the range of a couple hundred CPU cycles and the SSD is probably well over a thousand cycles though I have no exact figure for M1 where the SoC is also acting as the SSD controller.
That said, both Firestorm and Icestorm also have incredibly wide out-of-order re-order queues to keep themselves busy and schedule reads from memory or I/O and performing other tasks while waiting on the read.

The M1 also would use a little less memory for dedicated hardware DMA operations as it has a shared SoC level memory structure and most chips in the system are consolidated into that single system package so you don't need to keep duplicate copies of data from other devices - Though that is negligible on devices that have previously used iGPUs since there's not much other hardware in there with large independent memory space with consolidation pointers to system RAM. It could reduce RAM requirements of devices with dedicated GPUs somewhat though since normally, most data is kept both in GPU VRAM and in system memory and synchronised at certain points when there needs to be cross-hardware communication. Of course now that system RAM also belongs to the GPU but at least there's a smaller need for more RAM chips.

Though even if macOS is less RAM intensive on M1, there's no reason to believe the slew of Electron apps and others will be. Perhaps they will suffer a smaller hit from reaching swap with fast SSDs and the M1 acting as the controller with perhaps more direct access to the NAND, but I doubt the capacity needs are that much less, if at all, before you do hit swap. And swap is still orders of magnitudes slower, even if that speed penalty is hidden by good OOO reordering.

All in all my personal conclusion is thus:
Look at your workload in Activity Monitor on your current Mac. How much RAM do you have and what colour is the pressure graph? Make your decision based on that.
8 could very well be enough, but you can't change it later, so if you're pushing into the yellow or red with 8GB currently, I would get 16 for the M1 just to not regret it even if it's not felt as hard. And it while it might cost more I also do think the resale value for the future will be slightly higher; Not entirely offsetting the difference, but minimising it somewhat.
Don't buy excessively, but don't expect it to handle memory exactly like iOS - The macOS and iOS memory management systems and how much extra macOS needs to deal with is still a difference between the two platforms and macOS' multi-tasking model does not have the same suspend-stages iOS does. Apps in the background run more actively (iOS apps on the Mac somewhat being in a funky middle stage here since the code paths have the suspend stages and the associated frameworks are there, but the Mac will prefer having them more active even when backgrounded so that they respond immediately if things happen and can give visual cues even when they're not in the foreground, though it can still deep-sleep some aspects of the execution - WWDC talk exists that goes into more detail on that)
Good to see someone else that actually understands how this stuff works. There’s so much nonsense being posted that RAM is going to be used differently and somehow 8GB is going to be more than enough suddenly. No it’s not. If 8 GB wasn’t enough for you on x86 it’s still not going to be enough for you on ARM. 8 GB is pushing it these days even for casual usage. Have you looked at how many resources browsers alone consume these days?
 

casperes1996

macrumors 604
Jan 26, 2014
7,336
5,295
Horsens, Denmark
Good to see someone else that actually understands how this stuff works. There’s so much nonsense being posted that RAM is going to be used differently and somehow 8GB is going to be more than enough suddenly. No it’s not. If 8 GB wasn’t enough for you on x86 it’s still not going to be enough for you on ARM. 8 GB is pushing it these days even for casual usage. Have you looked at how many resources browsers alone consume these days?

Yeah. I mean, an 8 bit ASCII/UTF8 character is 8-bits no matter the platform :) - Of course there is room for some theoretical improvements like if the M1 has fixed function hardware blocks for efficient compression, Apple could use a different memory compression algorithm or something; Just an example, not something I think is happening - but at the end of the day it's not magic and even if there is some small difference it's unlikely to move the needle that much.

Browsers are basically small operating systems in and of themselves though. Of course they're commonly used apps so relevant to everybody, but they are likely also some of the more memory intensive casual apps you'll run by the nature of nearly being a little virtual machine. Interpreters, layout engines, rendering subsystems, WebGL to system graphics components, highly optimised JIT compilation and intelligent notions of what bits of JS to treat just as interpreted text and which to quickly compile to a more optimised form, lots of security systems and memory segregation systems and hardware and platform abstraction. It's honestly amazing that not just do we choose to build so much around such an encumbered architecture for the web. We go make Electron apps as well that takes that whole unnecessary chain to desktop apps as well instead of just interacting with the much, much slimmer stack the standard OS frameworks allows.
That's how we'll get iOS-like memory use btw. Not by changing the CPU architecture, but by getting programs that don't run through so many interpretation layers.
If I build the same UI, once with AppKit and once as a JavaScript based Electron app, the web-tech based system will without exaggeration use an order of magnitude more memory. And those are the kinds of apps we run a lot of the time.
Discord, Facebook Messenger on desktop, Visual Studio Code even. They run fine because frankly these JavaScript backends have become incredibly fast - but whilst their speed is still high (and Apple Silicon is by all accounts incredibly fast with JavaScript engines), it does come at a significant use of memory. And just to clarify, I mean fast relative to how many layers it needs to go through - native system frameworks will be equally fast or faster

But alas that's such a digression. There are valid reasons to write your app with web technologies - portability being a big one, so I'm not arguing against the practice entirely. Just putting some context into one of several reasons desktops often see greater memory usage - There's just often a greater software stack running even just for simple applications
 
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