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kemijo

Is AMD potentially risky? (Threadripper)

I've been planning a higher end home system for awhile with an i7, but now we have i9 vs Threadripper. Official benchmarks are out today and it seems silly to consider Intel for a HEDT machine for content creation primarily (gaming secondary).

For say, the i9 10 core vs the AMD 16 core, is this a no brainer? Are there any reasons why going with AMD at this point is a bad idea (besides slight edges in single core speed, etc)? I'm concerned that AMD may have unforeseen caveats in the future, e.g., something designed to take advantage of an exclusive Intel instruction set, etc. For a more concrete example, in this article about upcoming Renderman 22:

http://www.cgchannel.com/2017/08/pixar-unveils-renderman-22-and-renderman-xpu/

...it states "Other features due in RenderMan 22 include 'fast vectorized OSL shader network evaluation on Intel scalable-SIMD CPUs'," referring to the new Xeon Scalable CPUs. This may or may not be relevant as I am not considering a Xeon but is it possible that software from common vendors will simply not be supported by AMD?

Thanks for any insights!

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that's referring to AVX-512 most likely, so you need a Xeon currently 

https://en.wikipedia.org/wiki/AVX-512#CPUs_with_AVX-512

 

Embree uses it straight away, IIRC Vray uses Embree:

https://embree.github.io/

 

Good discussion here about AMD missing AVX 512. A bit too general/theoretical for us in VFX though.

https://forums.anandtech.com/threads/will-amd-support-avx-512-and-intel-tsx.2508094/

 

Oh Renderman uses Embree, that's why Pixar are pushing Intel in their press release I'm guessing and I'm double guessing that this is because of Animal Logic's Glimpse developer now working on Renderman.

https://rmanwiki.pixar.com/display/REN/Legal+Notice

Edited by marty

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"Is AMD potentially risky? (Threadripper)"

Yes, this is a terrible idea..

 

-Victor

PS: I may have a slight bias

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The old AMD chips work fine. The new Ryzen works fine. I don't encounter any problem with AMD CPU processors.

 

Edited by Atom

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Reading around about the Threadripper is pretty interesting - because it is two Ryzen 1800 chips glued together there is an option to turn off NUMA in the bios which may make for some minor performance gains/losses for simulations 

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On 8/13/2017 at 11:02 PM, marty said:

Reading around about the Threadripper is pretty interesting - because it is two Ryzen 1800 chips glued together there is an option to turn off NUMA in the bios which may make for some minor performance gains/losses for simulations 

can you expand on the topic ?

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For what it's worth I will be putting together my Threadripper build this weekend. There aren't any benchmark scenes for Houdini, are there?

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No standard test scenes but I would bet that it's approx 1/2 speed of a 1080Ti for OpenCL, read very good!, so I would be testing it as a substitute GPU for Houdini with heaps more ram and way more flexible.  It should be twice as fast as the Ryzen 1700 overall.

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The Zen cores are arranged in modules of 4. Intel cores are generally paired together with shared L2, though I think the latest iteration of Skylake-E removes that (7xx0 series).  It's pretty common practice to have cores share some resources to keep power requirements down.

Ryzen has two of those modules on a die with a memory controller. Threadripper has 4 modules with 2 memory controllers, and that's where the NUMA (non-uniform memory arrangement) and proper OS scheduling comes into play. The first 2 modules have access to one bank of memory, and the other 2 modules have access to the other bank. If a core from one module needs memory from the other module's bank, there's an extra hop to access the memory. That's the "non-uniform" part, since RAM latency can vary based on its physical location.

Accessing RAM is already pretty slow, which is why CPUs have large L3 caches, and use SMT (aka Hyperthreading(tm)) to hide the RAM access latency. Thread stalled on a memory request? Switch to the other one that's parked on the core and continue crunching numbers. The OS scheduler is also responsible for keeping threads on one module or the other if possible, so these days NUMA doesn't have quite the hit that it used to on the older multi-socket servers. That's why sometimes a software or firmware update is needed for new CPUs.

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