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Comment by chacham15 | Hacker News Reader

Im not sure this is true. Looking at the graph, the 970 outperforms the optane for sequential reads whereas the optane outperforms in the 4k random read/write range. So, it would seem that cases which are more sequential than random which include watching/streaming video/assets would run faster on the 970. So video game enthusiasts would still prefer the 970. If you're running a database, that 4k random read rate would seem to boost performance by quite a margin. Or am I missing something?

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Normal consumer workloads are heavily biased towards 4K random performance (especially read). Sequential performance is largely inconsequential, both because it's rare (how often do you really suck in a full 20+ GB file at a single go?) and because consumer SSDs are fast enough at sequential performance that it's not really a bottleneck. 500 MB/s sustained is really fast enough for most users.

Streaming video from the internet does not use the SSD at all, and a high-quality 1080p video file is maybe 5-10 MB/s of bitrate, you can easily pull that off a spinning HDD that was manufactured 20 years ago.

Video editing at 4K or 8K is one of the few use-cases where NVMe's sequential performance does provide a big benefit... assuming you are not editing using proxies.

Optane's QD=1 random-4K performance does present an opportunity for big speedups on consumer use-cases. But Intel really has to get the prices down if they want to see consumer adoption, right now there is an obvious benefit to cheaper SATA SSDs that allow you to get more data off spinning-rust drives vs a smaller, massively expensive Optane drive (even if it is incredibly fast).

I think GTA V or another AAA title could suck up 20Gb from disk to RAM/GPU in one go to load all assets (models, textures, audio).

But not necessarily as a sequential read.

I'm a little doubtful, on the basis that it would take HDD users about three minutes to load into the game (probably 4, by the time you start doing something with all those assets). I know HDDs are slow, but 4 minutes of loading is extremely excessive by any standard.

Also, on PS3 it runs in less than 256 MB of RAM... where is it loading these assets to? Most games have RAM consumption on the order of 4-8 GB in most situations, not all of that is assets, and not all of that is read sequentially.

You would think that, yet new World of Tanks patch introduced 10-20 second map load times for HDD users :-) SATA SSDs load in 1-2 seconds.

Planetside 2 would take 4+ minutes to fully load on the HDD before I upgraded to an SSD. Around 40 seconds on the SATA SSD. Haven't tried it on the m.2 yet.

Much less. Most gamers don't have 20GB VRAM GPUs. The game doesn't use 20GB RAM either, I think around 6-8 GB. So there's just nowhere to keep 20GB of loaded assets.

Video game loading is not improved past SATA SSD speeds, so there would be no difference between a 970 and Optane there. See https://www.youtube.com/watch?v=ecCA0gx_eZk

NVMe doesn't have much of an advantage over SATA SSDs at QD=1 in the first place. It really shines when you have higher QD or on sequential transfers, which are not typical consumer desktop workloads.

On the other hand, Optane does have a big advantage at QD=1, which is the point people are making here. Looking at NVMe as an indication of Optane performance is the wrong approach since it has very different performance characteristics.

https://img.purch.com/r/711x457/aHR0cDovL21lZGlhLmJlc3RvZm1p...

(of course you're not incorrect that games aren't really using access patterns that are optimal for superfast SSDs)

Sequential read/write is usually optimized for burst workloads on consumer ssd's. The Intel 900p can sustain its peak read/write performance for hours.

Anyway, the big difference with Optane is that its performance is more similar to having more system memory. I have not benchmarked this, but I believe a system with just 8GB ram + Optane will run better than a system with 16GB ram and Samsung 970 pro for workloads using up to 16GB of ram. There is a reason Intel announced its memory drive technology for Optane DC4800x https://www.intel.com/content/www/us/en/software/intel-memor...

EDIT: adding a link to lwn.net article explaing the use of swap/memory overcommit https://lwn.net/Articles/704478/

> but I believe a system with just 8GB ram + Optane will run better than a system with 16GB ram and Samsung 970 pro for workloads using up to 16GB of ram.

No, not even close. PCIe is still way slower than DDR4. Once your working set grows beyond available RAM, the Optane SSD will be a better swap device than any flash-based SSD, but you still notice your system slowing down drastically from all the swap activity.

Intel's Memory Drive Technology is really intended for situations where you have multiple Optane SSDs, and a workload that wants a large amount of total RAM but seldom has a true working set larger than actual DRAM capacity.

Nothing will beat a workload requiring 16GB of RAM, than a system with 16GB+ of RAM. You don't even need to benchmark to know that much.

for comparison, write speed to RAM on DDR4-3200 is somewhere between 50000 to 60000MB/second on a fairly normal skylake workstation platform.

PCIe latency is probably the bigger issue.

This. Which is why Intel is working on Optane DIMMs.

Traversing the root complex can take upto 100 cpu cycles each way.

yep but Optane DIMM /NVDIMM is not for client product. It is on data center product list. Persistent Memory isn't just a concept on the textbook. It be realized now.

So was Optane at first and so were SSDs in general. DDR4 already has an optional spec for NVDIMMs, DDR5 will make it mandatory.

Please forget Optane, just think about intel persistent memory. If you really care about performance /latency.

Nope that’s more like cache write speed. Single-threaded sequential access to RAM is typically more like 10-15GB/s for current server CPUs: https://panthema.net/2013/pmbw/results.html - it’s true that workstation machines tend to have somewhat higher sequential throughout compared to the server-heavy list at that URL, but it’s more like 20GB/s, not 50-60.

RAM is not nessisarily single threaded. Unganged Dual / quad channel memory is effectively multithreaded. So really his numbers are real world even with CPU bottlenecks. https://www.techspot.com/news/62129-ddr3-vs-ddr4-raw-bandwid...

PS: DDR4-3200W in quad channel mode is crazy fast and should break 100GB/s though sill a long way from a 1080Ti 484 GB/s.

Or a system with faster RAM or faster swap device :-D

One of the reasons SSDs felt so much faster than HDDs was the massive improvement in 4k r/w. If Optane is considerably faster in that space then it would definitely be a consideration as your primary/swap drive.

> One of the reasons SSDs felt so much faster than HDDs was the massive improvement in 4k r/w.

Also because that was a bottleneck. Now the CPU is often the bottleneck, so I doubt you'd notice Optane (most people can't even notice NVMe vs. SATA).

Samsung outperforms Optane in sequential read by 15-20% and loses at random read by 3-4x (at low queue depth). And watching video won't show any difference, you can watch 4K video from HDD. I know nothing about streaming, though, but I would be surprised if it makes any difference.

Typical database load is an example of big queue depths. You have dozens of queries executing simultaneously and you're interested in throughput. So Samsung SSD is fine there (and raids are even better), unless your database is not typical and serves only a single client with low latency requirement.

A typical db may do index scan on disk, which requires several times as many io operations per 8kb (Postgresql/Oracle size) page compared to seq scan. These are executed with low queue depth.

OTOH there's concurrency and prefetching logic increasing average queue depth.

Are index scans supposed to be faster with prefetch? It is random read at 8kb. I usually set read_ahead_kb to 8kb on disks/tablespaces for indexes.

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