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CPU affinity - two different approaches


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#1 Vond

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Posted 11 May 2012 - 03:07 PM

So, there are two different approaches to improving performance by changing CPU affinity from what I've seen. One is using Skyrim Extended Launcher to 'lock' Skyrim into using 2 specific cores (this is obviously only interesting for people with 4+ core CPUs), as the game only makes use of two anyway but what happens normally is that Windows spreads the load between all cores which means that CPU frequencies go up and down like crazy. Using SEL changes this as it will use those 2 cores fully improving stability and performance.
The other approach is to add some settings to your Skyrim.ini, assigning specific jobs to the different CPU cores. Following this guide assigns 2 cores to rendering, and 2 cores to AI and such.

The .ini additions (for 4 cores):


Now, you can't use both of these together, as doing one of these changes nullifies the other. Has anyone played around with these and can supply some insight on which approach seems to be working best for you? I will try out the .ini changes for starters myself, but actually comparing the two probably takes quite a lot of testing and thus if someone has already done so, sharing it would be great!
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#2 torminater

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Posted 11 May 2012 - 03:13 PM

so how can I divide all the tasks of skyrim on to my i7-2600k with 4 cores and 8 threads? is it the same settings?
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#3 Vond

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Posted 11 May 2012 - 03:19 PM

I would assume so as it's still 4 cores
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#4 frihyland

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Posted 11 May 2012 - 03:49 PM

You can also launch tesv.exe with the +fullproc switch. That forces the use of all cores.
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#5 TheCompiler

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Posted 11 May 2012 - 04:12 PM

When i set two cores with the launcher, my game FPS is halved, but when i select all core back my FPS returns to normal. I got a i7 core (4 core, 4 virtual cores)

#6 Vond

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Posted 11 May 2012 - 04:20 PM

When i set two cores with the launcher, my game FPS is halved, but when i select all core back my FPS returns to normal.
I got a i7 core (4 core, 4 virtual cores)


Ok, hadn't tried the launcher yet but that sounds interesting, in a bad way obviously. :) Been playing around some with the .ini tweaks and haven't noticed anything at all, and there might even be some performance increase although that might be placebo. Too early to tell yet.
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#7 ivactheseeker

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Posted 11 May 2012 - 04:29 PM

I tested the +fullproc in the launcher and did not improve the perforance for me. Are we sure Bedesda did't implement something in one of the patches?
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#8 Vond

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Posted 11 May 2012 - 04:37 PM

I tested the +fullproc in the launcher and did not improve the perforance for me.
Are we sure Bedesda did't implement something in one of the patches?

Fullproc never did anything for me even before the first patch, was something I tried at day 1 personally. :)
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#9 ivactheseeker

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Posted 11 May 2012 - 04:41 PM

That's probably why :D


I tested the +fullproc in the launcher and did not improve the perforance for me. Are we sure Bedesda did't implement something in one of the patches?


Fullproc never did anything for me even before the first patch, was something I tried at day 1 personally. :)


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#10 MadWizard25

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Posted 12 May 2012 - 03:48 AM

Glad you brought this up Vond, has been down as a "potential fix" under the discussion section for the troubleshooting wiki. Never gone live because I can only find one person on the nexus forums seems to have solved issues with this. This person, Xotana, tweaks the TESV shortcut target field by adding, to quote, "C:\Windows\System32\cmd.exe /c start "TESV.exe" /affinity 5 ... ( what follows is the regular game exe path - you will find it on your target path)". This forces a quad core to use two cores. The alternative method has already been mentioned, which is to use the Skyrim Extended Launcher. I think this "fix", will probably never be a fix, especially since it causes TC's game to crash. Just not enough evidence to support it yet. +fullproc will never do any harm, but will it help improve stability? This needs to be tested as well, and I have tried it out and could not notice any difference using Skyrim Performance Monitor. IN any case thanks for the ini tweaks Vond, will def be trying these out and will let you know how it goes :)
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#11 torminater

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Posted 12 May 2012 - 04:33 AM

i have the +fullproc tweak applied months ago. so far i can't tell if it runs more smooth or not, since game crashes are usually caused by too high ugrids or draw distances (tweaking with full step 2.1.1b is quite "risky" -.-)
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#12 thalastwon

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Posted 12 May 2012 - 01:34 PM

Currently running STEP 2.1.1b with SkyTEST and SkyRe. Everything has been run through by Optimizer Textures. I put in the .ini additions and my game crashed on boot the first time. I booted it again and it's been working fine ever since. Sadly I don't really see any large gain in fps. On the Whiterun steps I get 47-49 frames instead of 45-47. In the grass fields East of Whiterun I still get 45 frames. In the forest outside of Riften I get around 40-42, no change basically. Those are my only trouble places, everywhere else runs at 60 frames with or without the .ini tweaks. I have an i5 750 @ 2.6ghz overclocked to 2.9
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#13 Vond

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Posted 12 May 2012 - 05:48 PM

The tweak is mostly for stability, not really to gain large amounts of fps but rather to not drop as low in areas where you normally do. And that has been working quite well for me thus far. :)
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#14 thalastwon

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Posted 13 May 2012 - 02:55 AM

The tweak is mostly for stability, not really to gain large amounts of fps but rather to not drop as low in areas where you normally do. And that has been working quite well for me thus far. :)

In that case the .ini tweaks work pretty well for me, I have yet to see stutter after using them, that's definitely true.
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#15 MontyMM

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Posted 13 May 2012 - 07:10 AM

I'm a bit sceptical of these tweaks. Do we have enough information to be convinced that Skyrim only uses two cores (and why would that be the case)? What does this even mean if it will "spread the load" to four cores, and why should it be constrained from doing so? If the program is multi-threaded, will it not simply make best use of the cores available? EDIT: From the Intel support forum: "On a hyper-threaded processor with N physical cores and 2N hardware threads, it is often better to limit the number of 'busy' threads to N for extremely compute intensive applications (like Skyrim). This is because hyper-threading shares the resources of a single core between two hardware threads and if both of these threads are trying to run highly compute-intensive operations they compete (sometimes inefficiently) for the resources of that single core - often ending up running more slowly than a single thread running unimpeded on that single core. So what happens to the other hardware thread if you do this? Not much - it mostly just 'sleeps', servicing the occasional interrupt in the background but consuming almost no resources (and by servicing those background interrupts, it keeps the busy thread from having to switch context to service them). So you're best off to leave things alone and let Skyrim utilize the processors the way it is designed to do..." So, it might make sense to try and prevent Skyrim from utilising hyper-threading if it were running many threads, but Skyrim doesn't appear to do that, and this is not likely to be an issue. I doubt there is anything to be gained by forcing Skyrim to ignore available physical cores. I suspect that this is one of those tweaks born from Chinese whispers of a fuzzy understanding that Skyrim only runs a couple of threads, and doesn't benefit much from several cores.
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