Can the SSD speed of ~2.2 GBps for virtual RAM in 2018 13 inch base models make 8GB RAM sufficient?

[pubmsu]

Hi everyone,

The 2018 13-inch models have SSD read speeds of around ~2.2 GBps, which is equivalent to the DDR 333 RAM speed of yesteryears. Do you think this makes even the base model's 8GB RAM more tolerable or even sufficient?

2018 model RAM speed is 17 GBps, so the SSD speed is not an order of magnitude slower, it is just 8 times slower. macOS manages virtual RAM very efficiently as well.

RAM speeds: https://www.transcend-info.com/Support/FAQ-292

I am mainly asking about read speed.

Am I missing something?

Thanks!

 

[Lennyvalentin]

2018 model RAM speed is 17 GBps, so the SSD speed is not an order of magnitude slower, it is just 8 times slower.

2018 model MBPs use dual channel 2133MHz DDR3, and whatever MHz DDR4, I can't be bothered to check so let's go with this figure, so ~34GB/s best case. You're not going to hit it because of reasons, but best real-world case is quite likely still going to be more than 17GB/s.

Am I missing something?

Latency. DRAM has access speed measured in what, 10-20ns or thereabouts. The fastest SSDs have access time of .1ms or so. So we're talking 500,000 times slower, something like that, and then we have slower data transfer speed of the SSD laid on top of that as well. So if you're hitting your page file a lot the system is going to feel stuttery and chugging. Then again, 8GB is quite a lot of RAM also, so depending on what you're doing you might not actually suffer enough to notice it.

You should check how much RAM you're actually using, and then make your decision...