PrimoCache performance on PCIe 4.0 vs 3.0? Slot 1 vs 2?

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Toyzrme
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PrimoCache performance on PCIe 4.0 vs 3.0? Slot 1 vs 2?

Post by Toyzrme »

Has anyone tested performance of using L2 cache on PCIe 4.0 NVMe vs 3.0? (on a PCIe 4.0 MoBo, of course)

Or on the first NVMe slot vs. second? (i.e. CPU direct PCIe lanes vs. via chipset, assuming that's connected via PCIe 4.0)

Just curious whether it's worth:
1) Paying for PCIe 4.0 NVMe drive (like 980 Pro)
2) Using the 2nd NVMe slot as the boot drive, so that the L2 cache is closest to the CPU for less latency

Any thoughts? Would I even notice the differences?

System-to-be: AMD 5950x 16c, X570 MoBo, 128GB, 2x NVMe (OS + cache), RTX3080, 35TB RAID6 (5x HDD), 4K display
Uses: Video and image editing
xinwei
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Re: PrimoCache performance on PCIe 4.0 vs 3.0? Slot 1 vs 2?

Post by xinwei »

It depends on the SSD itself. Currently most nvme SSDs support PCIe 3.0x4 which speed limits to 4GB/s in theory. Some SSDs now support PCIe 4.0, and their speed beyond 4GB/s.
Babel17
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Re: PrimoCache performance on PCIe 4.0 vs 3.0? Slot 1 vs 2?

Post by Babel17 »

I think that latency could be among the most important concerns with a L2 cache, and IIRC all SSD are excellent in that regard. I have a PCIe 4.0 NVMe drive on a X570 mobo, with an AMD 5900X which it was inserted next to. It is pretty much tied for being the fastest drive around, a one TB WD Black SN850. For moving data around it's wicked fast, but clicking on a file on it vs. clicking on a file on my five year old Mushkin Striker SATA SSD is about the same.

So if using L2 set to read only, which is what I have the L2 cache on my older NVMe drive which sits in the other NVMe slot in my ASUS mobo, then you should be fine with whatever you go with. Though these drives are supposed to last a long time, so it might be worth spending a few extra dollars for something that will be used later on in other PC builds that you have.

If you are most concerned about gaming, then benchmarks show that level loads are excellent no matter what SSD you have. The most expensive drives can sort of justify their expense if you are looking at long and brutal drive writes, ones that exhaust their internal ram cache, and SLC pseudo cache. Then the controller has to work its magic, as do the underlying cells of the drive.

Edit: Sorry, you spoke of video editing. Btw, I too have a RTX 3080, and a 4K TV/monitor. I guess if video editing causes you to wait on huge files of raw video streaming from drive to drive as they are edited, and transcoded, you might want a crazy fast NVMe drive. Are you getting a pre-built? It's nearly the only way to get the parts you mention. That's what I did, from Cyberpower PC.
Toyzrme
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Re: PrimoCache performance on PCIe 4.0 vs 3.0? Slot 1 vs 2?

Post by Toyzrme »

Thanks - there are so many benchmarks, statistics, and opinions out there, it's hard to get/formulate a clear, definitive answer (and yes, I know it depends on a lot of parameters).

Sounds like we'd get along - I have a 50" 3D 4k TV as my monitor. Building my own system - still waiting for my 5950x to come in (until then, running a 3600 on my x570 MoBo). I have a GTX 1080, which hopes to someday grow up to be a 3080, if/when they return to retail prices (hey, stop laughing!!!). The MoBo is filled with 128GB of 3600 RAM, and I decided to go with a 1TB 980 Pro for boot, and 2TB 980 Pro for cache and/or fast source storage, depending on testing (Puget DaVinci benchmarks). Was torn on the SN850 ...

The part that uses a lot of file seeking is scrubbing through the footage - so you're jumping around in big files, pulling a few frames, then jumping again. That's why I'm leaning towards just putting all 2TB in front of my 32TB RAID6 HDD set, and let Primocache figure it out (probably no L1?). Then put a modest RAM cache (L1) in front of the boot drive (10-20GB).

May last build is 5 years old, with a 512GB Samsung 951 NVMe - 1,800/1,300 MB/s, and $350. Wow, huh? LOL 250TB written without using it very heavily.
0ldman
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Re: PrimoCache performance on PCIe 4.0 vs 3.0? Slot 1 vs 2?

Post by 0ldman »

Just my experience, the video editing and encoding likes L1. The software I use doesn't use a ton of RAM but quick IO helps in editing and 16GB of L1 has a pretty decent amount of IO potential.

If your app caches the video file properly in RAM as you're working with it you won't need the L1, if you're like me and use a bunch of cobbled together open source apps the L1 is a godsend. I typically don't work with anything above 1080P but seeking, trying to go frame by frame, etc, is instantaneous with the L1 cache and just pretty quick without.
bushwacker611
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Re: PrimoCache performance on PCIe 4.0 vs 3.0? Slot 1 vs 2?

Post by bushwacker611 »

I'm running on PCIe 2 on what was a medium-high end HP gaming system from 2013. I've since overclocked it, upgraded to 32GB of the highest performance DDR3 I can get, and installed a Samsung 860 Pro SSD as my primary disk. Using PrimoCache (better than the stock Samsung caching software, which is pretty decent, all told), I noticed a major difference.

To put it in perspective, my old 7200RPM magnetic disk performed about 80-85% as well vs a generic SSD in Anvil/PCMark benchmarks, and was WAY faster in terms of subjective performance. Without caching, my new SSD performed about as well as that PrimoCache/HDD combo did prior to the upgrade. With Primocache enabled, my performance is about 5-10% better than the free Samsung caching app for gaming, my most intensive application (mostly reads with some writes).

Overall, I'd expect performance boosts to be more drastic on lower performance hardware, and less so on higher end equipment. That's normal for anything really. My MO is always to get the L1 as high as I can without running out of memory and set that as your default. If you're like me and have only one app that crashes, lower it to the minimum stable when using, then jack it up again for everything else. This is only practical if that one app is something you're not using every day- in that case I'd just make that the lowest common denominator and live with it.

ALSO (sorry this is long winded), make sure your drivers are up to date, and use MSI Utils and LatencyMon to see if you can tweak process priorities to prefer the PCIe controller (if multiple) that the disk in question is on. Do the same for the drive in question (if only one is the priority). If you want to get really crazy, you could put your priority partition first, but I don't know if that makes a real difference on modern SSDs (if someone knows, let me know). Check out https://www.youtube.com/channel/UCzBPlB ... fP1Uk4RKaw for some additional details on this stuff. This YT channel is focused on maximizing gaming performance, but a lot of these tips could be translated into server or workstation use cases with few to no changes.
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