CPUs for Zerene/general image processing: cores or clock?

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bralex
Posts: 129
Joined: Mon Jan 22, 2018 11:34 am
Location: New Mexico, USA

CPUs for Zerene/general image processing: cores or clock?

Post by bralex »

I'm pulling together a new computer; other than typical word processing/web surfing I'd like to optimize for stacking and other image processing. If I had a lot of money I'd buy the top tier CPU, but like most people I'm just trying to work the middle as best I can. I figure I can swing a good mid-range CPU; for my money I can either go for 4 faster cores (e.g. Intel i7) or 8 somewhat slower cores (e.g. AMD Ryzen 1700). I know that for general office loads a single slow core is good enough! I'm not sure how software like Zerene makes use of CPUs. I did read some older threads about improving performance in Zerene, which suggested that it makes good use of multiple cores.

Either is going to be a clear improvement over my current system, so I'm not too stressed about it, just looking for ideas.

Thanks,
Scott

rjlittlefield
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Post by rjlittlefield »

How much "faster" versus "slower" are we talking about?

If it's say 8*3.4 GHz versus 4*4.2 GHz then I'd go with the more cores because the 1.6X higher raw computational capacity probably outweighs Zerene's loss of efficiency with more cores. If the gap is wider, I'd have to think harder.

Also important for speed is to be using a Prosumer or Professional license for Zerene Stacker. That's because the Pro licenses provide overlap of I/O and computation, which results in a large improvement in performance due to eliminating serial sections (times when only one processor is busy).

--Rik

bralex
Posts: 129
Joined: Mon Jan 22, 2018 11:34 am
Location: New Mexico, USA

Post by bralex »

You answered what I wanted to know - on this level at least Zerene will scale well with cores. My old i5 will soon be headed off to a well-earned rest!

bralex
Posts: 129
Joined: Mon Jan 22, 2018 11:34 am
Location: New Mexico, USA

Post by bralex »

I ended up picking up a Ryzen 1700x, along with a new motherboard and RAM. I don't have the specs on my old system, it was an i5 with 8 GB. I did a couple of stacks before I upgraded, and roughly timed them, then ran them again after the upgrade. The new system is about 2.5x faster (roughly 10 min vs. 25 on the old system). I didn't change hard drives. Usually when stacking Zerene pulls about 65-70% of the CPU, with 16 virtual cores (8 actual cores, hyperthreading) running.

rjlittlefield
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Post by rjlittlefield »

Good data point.

Is that with I/O overlap working?

You can tell for sure by checking the console log. What you want to find is one line that says "Overlapped I/O Permitted = true", followed by lots of lines about "Starting preload". If you have screen preview caching turned on, then there should also be lots of "Asychronously writing preview file".

--Rik

bralex
Posts: 129
Joined: Mon Jan 22, 2018 11:34 am
Location: New Mexico, USA

Post by bralex »

Yes, I'd followed your earlier thread about performance improvement.

I will note that on the previous system Zerene hit all 4 cores for 100%, minus a little system overhead (3-5%). On this system it peaks at 65%, with system overhead still in the 3% range. There may be some headroom available in systems with more cores/threads, or it may be an artifact of going from a 1:1 core:thread ratio to a 1:2 ratio. Superficially, another ~30% core utilization would amount to an almost 50% speed increase, but there may be a different bottleneck somewhere - I/O for example.

I'm really enjoying Zerene, I was using CombineZP but that appears to no longer be maintained.

Edit: fixed typo

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