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Memory is slow, Disk is fast – Part 1

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Re: Memory is slow, Disk is fast – Part 1

#21

Post by kamranjon »

bolster wrote: post #20

> Data used for the charts was researched and compiled by ChatGPT, I spot checked it and found it was accurate enough to for the narrative. Last I checked, that wasn't how citations worked. I only sampled one data point (2017 AMD EPYC Rome Clock rate) which was significantly off, because in 2017 it was the Naples chipset that was released, and, unless 2017 was desperate enough to clock from 2.2Ghz to 3Ghz on the regu…

I read the whole thing but I got a strong AI vibe about half way through, felt like it was significantly padded with extra words to extend its length. Kind of annoying that blurb wasn’t placed at the beginning of the article…

Re: Memory is slow, Disk is fast – Part 1

#22

Post by PaulKeeble »

fizzynut wrote: post #19

Ai generated slop. Constantly summarising various parts of the memory hierarchy, graphs with no x axis, bad units, no real world examples, the final conclusion doesn't match the previous 10 summaries. The big problem is that it misses a lot of nuisance. If actually try to treat an SSD like ram and you randomly read and or write 4 bytes of data that isn't in a ram cache you will get performance measured in the kilobyt…

SSDs have so many cases of odd behaviour. If you limit to writing drive sector chunks, so 4k, then at some point you will run into erase issues because the flash erase size is considerably larger than the 4k sectors. But you also run into hitting the limits of the memory buffer and the amount of fast SLC as well which limits the long term sustained write speed. There are lots of these barriers you can break through and watch performance drop sharply and its all implemented differently in each model.

Re: Memory is slow, Disk is fast – Part 1

#25

Post by proggy »

bolster wrote: post #20

> Data used for the charts was researched and compiled by ChatGPT, I spot checked it and found it was accurate enough to for the narrative. Last I checked, that wasn't how citations worked. I only sampled one data point (2017 AMD EPYC Rome Clock rate) which was significantly off, because in 2017 it was the Naples chipset that was released, and, unless 2017 was desperate enough to clock from 2.2Ghz to 3Ghz on the regu…

I feel like our planet’s long-term academic health would dramatically improve if something resembling the following statement was posted on the wall of every K-12 and college classroom:

ChatGPT is not a primary source. Wikipedia is not a primary source. Google Search is not a primary source. Microsoft Encarta is not a primary source. The Encyclopedia Brittanica is not a primary source.

Information aggregators are not primary sources. Identifiable people are primary sources.

Re: Memory is slow, Disk is fast – Part 1

#26

Post by marcosdumay »

crawshaw wrote: post #13

A title of "Memory is getting slower, Disk is getting faster" might remove a lot of the initial confusion this post causes.

Except that the article doubles (or rather, triples) down on claiming that reading from the disk is faster than from the memory despite all of CS (CS, really? That has nothing to do with CS on reality) "dogma" claiming otherwise.

It's a weird article. It looks at an insightful set of numbers, fairly accesses them, and then goes on to conclude the stupidest thing.

Re: Memory is slow, Disk is fast – Part 1

#27

Post by Swizec »

AshamedCaptain wrote: post #10

The data does not support the premise much less the grandiose conclusions at the end of the article. By pure construction memory is always going to be faster than disk, right up to the point where disk is inplemented as memory which makes this a pointless semantic discussion. Such a fact would hardly invalidate the core pillars as computer science as the conclusions imply. Waste of time.

> By pure construction memory is always going to be faster than disk, right up to the point where disk is inplemented as memory

You can get servers with terabytes of RAM these days. How many startups’ and small to medium businesses’ entire production database could fit in memory on 1 server?

Hint: the answer is “a large majority” (numerically, not by market cap)

Yes RAM is faster than Disk, but for most people it may simply not matter anymore. Put everything in RAM, sync to storage periodically in the background.

Re: Memory is slow, Disk is fast – Part 1

#28

Post by jeffbee »

vlovich123 wrote: post #18
jeffbee wrote: post #6

There's some sleight of hand being perpetrated here through the use of an inappropriate scale to trick the reader into thinking that NVMe latency is roughly zero when it's not. Let's just stipulate that you have an unreleased, hypothetical NVMe device with consistent 10µs read latency. The same device will have a write latency 10-100x higher, which it hides, under transient conditions, with DRAM. It's a very poor men…

The article feels like LLM output. Some correct facts strung together to support an incorrect thesis the author asked it to validate, but completely ignoring inconvenient facts and reaching a wild conclusion that isn’t actually true.

That's what it says it is at the very bottom.
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