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Some Advice on Processor Affinity

ttaylor1

Junior Member
Nov 3, 2017
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Hey Guys,

This is my first post on this forum. We're currently trying to update our machines on the Technical Design team here where I work. My machine is exempt because it's somewhat dual purpose. This post is gonna be somewhat long but I'm kind of at the end of the rope lol

I'm using a 7700k with 32 GB of RAM, and dual GTX 1080Ti's and I use this machine for rendering. However I have to use it for SketchUp regularly, and Revit every now and then. We've run into a roadblock today specifically because we've received a Revit file that's 900 MB which is ridiculously big for our machines.

I've been tasked with configuring some machines that would be able to handle our Revit workloads easily. I currently recommended a 7940X with 64 GB of RAM and a 1080 Ti. I know traditionally this calls for a Xeon/Quadro configuration but I've consulted several companies about the i9/GTX configuration.

Anyways the 7940X is a 14 core processor which would be awesome but the Technical Director is somewhat apprehensive about it from the perspective of whether or not it's necessary. Anyways. Our current issue is that we're trying to import a DWG, that was exported from Revit, into SketchUp. My coworker and I split the file into two halves in order to try and cut down the import time, and we stripped the file as much as possible.

I'm running a 7700K and he has a 4790K I believe. We have the same RAM capacity - 32 GB. But both of our machines have been running overnight and they're still not done importing the files.. Part of that is SketchUp. However I ran across Processor affinity.

My question is somewhat two fold. What does this actually affect regarding 3D modeling programs? I can find info on Hyperthreading and gaming and processor affinity and can kind of understand it. However SketchUp from what I understand is a single core/single thread application and if I understand that correctly it doesnt matter what CPU we get - it would still import at the same speed.

The other part of my question is how setting the CPU affinity mid-import like that would affect the performance. I can look at Task Manager and see that my CPU is only at about 23% overall and 37% of my Memory. I'm currently running the import and rendering a flytrhough animation in Lumion (GPU based rendering engine). SketchUp is using more of the CPU than Lumion but I'm not at 90% or 100% which is usually when people start messing with affinity from what I've read.

When I look at the details there is a "12" in the CPU column on the SketchUp line and it's using about 300MB of Memory (private working set). I can go up to Lumion and it goes between 4 and 5 in the CPU column and 1.1 GB in the Memory column. Could you guys explain what that means and how to compare that to the overall allocations?

This Revit process has been pretty screwed up because of this long import time and we can't really figure out why it's acting this way. Would changing the affinity for SketchUp change the outcome at all?

Thanks for any help you guys can give me.

T.
 

TheELF

Diamond Member
Dec 22, 2012
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Affinity allows you to put a task on a single core(or multiple ones) ,so it would only run on that one core.
It's only useful if you run multiple programs at once and they mess each other up in that case you use affinity to separate the programs and put each one on their own set of cores.
In your case it won't do anything,it might even slow it down a bit since windows always chooses the best core (most idle one) to run a heavy workload by using affinity it will keep running on that core even if there is something else running that takes up a lot of resources.
 

Ferzerp

Diamond Member
Oct 12, 1999
6,429
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Outside limited scenarios (something like linpack), it is pretty useless. Take anything that “gamers” suggest with a grain of salt. They perpetuate silly things like command line options that don’t even do anything at all with a given game just because it’s a flag that has a function with a different game and other bizarre things.
 
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PeterScott

Platinum Member
Jul 7, 2017
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Outside limited scenarios (something like linpack), it is pretty useless. Take anything that “gamers” suggest with a grain of salt. They perpetuate silly things like command line options that don’t even do anything at all with a given game just because it’s a flag that has a function with a different game and other bizarre things.
Well said. I play a lot of old games and the stuff I see suggested on the GoG forums as sure fire fixes are essentially just repeated superstition. They may as well be telling people to dance a circle around their PC... CPU Affinity is an often used one, that really does nothing useful.
 

rvborgh

Member
Apr 16, 2014
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i've found Process Lasso (which allows you to program affinities for any apps you have installed) very useful on my 48 core Opteron. For a while i had 16 out of 48 running at 3.6 GHz, and just pinned all apps to those (the rest i just had running slower).

On an Intel with hyperthreading... you might try pinning apps to every other logical core to see if it makes a difference in speed.

On my quad socket setup... it was useful to keep some apps running on a single socket (ie 12 cores)...
 
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