Difference between cores and processors?

[atsf189 460]

What is the difference between the number of cores your processor has and the number of logical processors it has?

How should the number of logical processors be set for SimCity 4 best performance?

Should I be using only one logical processors so the game does not get confused?

[matias93 7,535]

2 hours ago, atsf189 said:

What is the difference between the number of cores your processor has and the number of logical processors it has?

How should the number of logical processors be set for SimCity 4 best performance?

Should I be using only one logical processors so the game does not get confused?

The number of cores is the number of processors physically etched on the die. The number of logical processors is usually double the number of cores, achieved with techniques like hyperthreading, that schedule tasks speculatively to optimise core usage.

Most of this was developed for consumer computing after SimCity 4 was released, so the game doesn't know how to take advantage of it and mostly struggles with anything other than a single core and a single thread. The CPUCount:1 command should suffice to make the game able to use one single core and one single thread, reducing the risk of crashes to desktop.

I haven't researched it well, but I get the sensation that disabling hyperthreading (or its AMD equivalent) can help the game stability somewhat, at the cost of processing power overall for your computer. Some security experts also advise to disable it, as it has been shown it can be a vulnerability.

[atsf189 460]

Thank you for the information.

With CPUCount:1 the game is still using all of my logical processors and i can change this with the affinity setting but I am not sure if helps or hurts with less  logical processors being used?

[rsc204 21,867]

10 hours ago, atsf189 said:

With CPUCount:1 the game is still using all of my logical processors and i can change this with the affinity setting

First you should check the command is correct, it should include a hyphen, i.e. -CPUCount:1, perhaps that explains why it isn't working? 

You can also use the Set Affinity option in Windows, it's essentially the same thing, but you need to alter the setting every time you run SC4. There isn't a good reason why using the command won't work, so ideally you want to fix whatever is wrong there so that the setting is used automatically when playing the game.

11 hours ago, matias93 said:

I haven't researched it well, but I get the sensation that disabling hyperthreading (or its AMD equivalent) can help the game stability somewhat, at the cost of processing power overall for your computer. Some security experts also advise to disable it, as it has been shown it can be a vulnerability.

Hyperthreaded (HT) processors show each physical core as two logical cores in Windows, so if you force SC4 onto a single core, there will be no use of HT within SC4 anyhow.

As for disabling it for the entire system, that's a bit drastic and for the average user is not going to be positive overall. Because Windows can make use of HT and so can most modern apps you may use, essentially it's turning off extra processing power you paid for as an extra feature. It's like buying a car with a Turbo or Supercharger and then switching it off because you didn't want extra power. If you didn't want the extra power, why pay for this feature in the first place? I don't believe there is an equivalent technology used in AMD chips, which are built differently and of course can't use an Intel owned technology.

In theory, SC4 will run faster without HT enabled on your system, it's explained well here:

Quote

Yes disabling HT will give a small boost to single threaded performance. The cores are no longer divided and sharing work, so the one thread going to each core gets the complete attention of that core, so the single thread performance will slightly improve.

However, since your OS and almost all apps made more recently, i.e. those designed for the multi-core world we've been in for 15+ years, will all run worse if you do this. It just doesn't make sense for the average user to disable this feature, you'll be making more things slower to make one thing a tiny bit faster.

As for security issues surrounding HT, it's very complicated and depends whether or not your hardware (BIOS) or operating system include fixes for the known issues (from the linked article by Matias), most systems will no longer have these vulnerabilities. Likewise more recent hardware should not have the problems to begin with. For the specific issues mentioned in relation to HT, those using Window 10 (fully updated) should be protected.

Ultimately if you are using older hardware and/or a version of Windows before 10, you probably don't have a secure PC. Patches and bugfixes are key to keeping a secure computing environment, so as soon as you no longer get updates, you must assume your system is potentially vulnerable.

[atsf189 460]

RSC204 you are correct -CPUCount:1 does make it run on only one logical processor.

I had the wrong command -CPUPriority:1.

The game was crashing once in a while so I will try the correct command.

I am using this now:

C:\Windows\System32\cmd.exe /c start "SimCity 4.exe"  /high "C:\Program Files (x86)\Maxis\SimCity 4\Apps\SimCity 4.exe"  -CPUCount:1 -Intro:Off -CustomResolution:enabled -r1920x1080x32 -d:DirectX -Cursors:fullcolor

This line makes the priority high 

C:\Windows\System32\cmd.exe /c start "SimCity 4.exe"  /high

 

4 hours ago, rsc204 said:

You can also use the Set Affinity option in Windows, it's essentially the same thing, but you need to alter the setting every time you run SC4. There isn't a good reason why using the command won't work, so ideally you want to fix whatever is wrong there so that the setting is used automatically when playing the game.

You can make a shortcut to pick the amount of logical processors you want to use

C:\Windows\System32\cmd.exe /c start "SimCity 4.exe"  /affinity ff

above runs all of mine I have 8 the number is hexadecimal. This explains how it works

 https://www.eightforums.com/threads/cpu-affinity-shortcut-for-a-program-create-in-windows.40339/

It does not work if you use -CPUCount:1

It seems like CPUCount  and affinity are two different things

If I just change affinity and NOT CPUCount wouldn't the game still be using all the cores and only the logical processors I choose?

I wonder what effect only changing the logical processors has on the game?

[rsc204 21,867]

Hyperthreading is the reason why one core appears as two in Windows. In reality you have a four core processor where each core can, under the right circumstances, do two things at once as if you had twice the number of cores, but not really. It does provide a performance boost for apps designed to utilise HT, but more actual cores would theoretically provide more performance.

Set Affinity just allows you to toggle both how many and which cores are used for a running program. As part of Windows in can be invoked in the command line even via shortcuts in this manner.

Whereas the commands SC4 uses are actually part of DirectX, like -CPUCount:# - you can change # to any number you like. But for the sake of preventing instability for SC4, you must set it to 1.

You can use either method to achieve effectively the same results. But if you used both and they were set differently I honestly don’t know which would win out. It’s just easier to set the -CPUCount:1 command for most users, so that’s the tried and true method I would recommend to everyone. Especially since most of us need more than one such command to run SC4 correctly.

The bottom line is, unless you restrict SC4 to a single core (logical or physical), you will have a problem with frequent CTDs.