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Author Topic: 8 cores versus 6 cores makes a difference for Lightroom?  (Read 12765 times)
kaelaria
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« Reply #20 on: February 16, 2013, 10:55:28 AM »
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Lol it wouldn't surprise me in the least if some of these guys don't know the difference Smiley
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Rhossydd
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« Reply #21 on: February 16, 2013, 11:40:42 AM »
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Not wanting to step on any toes here but this image is for rendering isn't it.. not import? 
Indeed, for me rendering 100% previews is part of the whole importing process.

The important aspect here is not some pedantic inspection of the process I used for my screen shot, but whether LR uses multiple cores. I think my screen shots are  pretty emphatic examples that it does.
I always have the CPU usage widget running on my desktop and it's pretty clear that LR uses multiple cores to speed things up on virtually every task. Even throwing the sliders about in develop can cause the CPUs to max out briefly (see attached screen shot throwing the CT about).



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kaelaria
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« Reply #22 on: February 16, 2013, 01:41:05 PM »
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Thanks for proving my points! You are now options one and two at the same time Smiley
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Rhossydd
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« Reply #23 on: February 16, 2013, 01:58:51 PM »
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Thanks for proving my points! You are now options one and two at the same time Smiley
You're very quick to criticise, but so far you've offered no explanation of why LR would be behaving as it does or offering any evidence that it doesn't use multiple cores.

Adobe in their own document on optimising Lightroom's performance at http://helpx.adobe.com/lightroom/kb/optimize-performance-lightroom.html say:-

"Options that can help increase performance include:

    64-bit, multiple-core processor (for best performance, up to six cores. The extra power is especially important if you use multiple or high-resolution monitors which require more power)."

Are they wrong too ?
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kaelaria
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« Reply #24 on: February 16, 2013, 03:32:29 PM »
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You obviously didn't watch, or are incapable of comprehending, the video I posted.  Good luck - those with more common sense will benefit from it Smiley
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Rhossydd
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« Reply #25 on: February 16, 2013, 04:50:01 PM »
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You obviously didn't watch, or are incapable of comprehending, the video I posted. 
Yours ? oh dear Sad

You're using a system that you admit is bottle necked by the disk system (your quote @ 2:45), hardly the basis for any credible demonstration is it ?

Then you think a quad core system running at over 70% utilisation across all cores isn't using multiple cores ?

And you have no answer to why Adobe recommend using multi cored systems or why systems suddenly jump to 92% utilisation when throwing the CT slider around in the develop module ?



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lfeagan
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« Reply #26 on: February 16, 2013, 10:28:57 PM »
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I have many systems running LR. One is a dual core with hyper-threading (appears as 4); LR imports use 4 threads for importing on this system and all are maxed. I have a quad-core system hyper-threaded as 8. On this system imports don't max all cores, but most of them are churning away at very high utilization. I also have an 8 core system hyper-threaded to 16. On this LR doesn't use more than 8 threads. It basically schedules 1 thread/physical core and the hyper-threading capability doesn't figure into it.
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Lance

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Joe Schwartz
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« Reply #27 on: April 28, 2013, 01:08:32 AM »
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Here's what happens when LR is building the 1:1 previews:

Jim, I'd be interested to see what your CPU usage charts look like with HyperThreading disabled, or with LR set to use only the 12 physical cores in your machine. (You can set the latter by right-clicking lightroom.exe in the Processes tab of Task Manager, selecting "Set Affinity", and then unchecking all of the odd-numbered CPUs, leaving the even-numbered ones checked. The even-numbered CPUs represent the physical cores.)

I've been running similar perf tests on my 4-core machine (8 logical cores with HyperThreading), both for rendering 1:1 previews and for exporting a set of images.  In each case, LR4 (and LR5 Beta) uses at least 4 threads to render or export each image.  (I suspect it uses each thread to render a different part of the image, with another thread to combine the results into a finished preview or exported image.) When I disable HyperThreading on my machine, all 4 cores have steady peaks at 98-100% utilization for each image, with dips to 25-50%.
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Jim Kasson
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« Reply #28 on: April 28, 2013, 06:02:04 PM »
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Jim, I'd be interested to see what your CPU usage charts look like with ... LR set to use only the 12 physical cores in your machine.

Joe,

I followed your instructions and got the same results. I don't think the resource monitor changes the denominator when a program is restricted to the physical cores, so what that means is the task is running at about the same speed with the change you suggested as before. I tried building previews and exporting.

Jim
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Joe Schwartz
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« Reply #29 on: April 28, 2013, 06:08:18 PM »
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I followed your instructions and got the same results. I don't think the resource monitor changes the denominator when a program is restricted to the physical cores, so what that means is the task is running at about the same speed with the change you suggested as before. I tried building previews and exporting.

Thanks, Jim. You're right, the denominator doesn't change unless you disable HyperThreading at the BIOS level. So your total CPU utilization was around 21% when using just the 12 physical cores?
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Jim Kasson
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« Reply #30 on: April 28, 2013, 06:28:47 PM »
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Thanks, Jim. You're right, the denominator doesn't change unless you disable HyperThreading at the BIOS level. So your total CPU utilization was around 21% when using just the 12 physical cores?

At best...
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