Windows: Implement `cpu_physical_cores` and `cpu_cores`

[Carterpersall]

Hello, I'm a contributor to https://github.com/lptstr/winfetch (you've talked to the maintainer in #112), and would like to start applying some of the experience I gained there to this project.

• cpu_physical_cores
  • Uses the implementation in https://github.com/seanmonstar/num_cpus/blob/master/src/lib.rs#L129
  • Calls GetLogicalProcessorInformation and uses the returned buffer to get the computer's number of CPU cores
• cpu_cores
  • Gets HKLM\HARDWARE\DESCRIPTION\System\CentralProcessor and counts the number of subkeys

[CarterLi]

You may get physical cores and logical cores ( threads ) at the same time with GetLogicalProcessorInformationEx(RelationAll)

https://github.com/LinusDierheimer/fastfetch/blob/b3da6b0e89c0decb9ea648e1d98a75fa6ac40225/src/detection/cpu/cpu_windows.c#L17

Because this method requires copying more data from the kernel, I'm not sure whether it's faster than your implementation. Just another idea.

[Carterpersall]

I added several alternative implementations

Implementation Speeds:

• Command used: hyperfine --warmup 20 --prepare "cmd" --min-runs 200 ".\macchina.exe --show processor"
  • Compiled in release mode

Plugged in:

• GetLogicalProcessorInformation
  • 13.6 ms
• Environment Variable
  • 13.7 ms
• Registry
  • 13.7 ms
• GetNativeSystemInfo
  • 14.0 ms
• Physical Cores (also GetLogicalProcessorInformation)
  • 14.0 ms

On Battery life:

• GetLogicalProcessorInformation
  • 30.8 ms
• Environment Variable
  • 31.2 ms
• Registry
  • 31.1 ms
• GetNativeSystemInfo
  • 30.7 ms
• Physical Cores (also GetLogicalProcessorInformation)
  • 31.1 ms

When heavily throttled (used power plans to downclock CPU to 1.06 GHz to simulate a slow computer)

• GetLogicalProcessorInformation
  • 55 ms
• Environment Variable
  • 53.5 ms
• Registry
  • 54.6 ms
• GetNativeSystemInfo
  • 54.3 ms
• Physical Cores (also GetLogicalProcessorInformation)
  • 54.7 ms

[grtcdr]

There's virtually no difference between some of the implementations and those of num_cpus, why not call those two functions directly?

[CarterLi]

According to stackoverflow, WMI, registry and GetLogicalProcessorInformationEx are only reliable ways to get the number of cpu logical cores (threads)

[Carterpersall]

According to stackoverflow, WMI, registry and GetLogicalProcessorInformationEx are only reliable ways to get the number of cpu logical cores (threads)

That does seem to be the case. I've made a commit that addresses it. cpu_cores now uses GetLogicalProcessorInformationEx to get the number of cores, and has Registry and WMI based implementations as backups. cpu_physical_cores now uses GetLogicalProcessorInformationEx as well.

I used the implementation here as the basis of my implementation of GetLogicalProcessorInformationEx.

[IAMSolaara]

Hi, I'm making a tool that can benefit from this. Any way we can get this merged?

[grtcdr]

I've got a Windows VM lying around but I'm a bit busy at the moment. If this works correctly, I don't have a problem accepting the PR. I would appreciate @uttarayan21's input on the state of this PR because he's much more knowledgeable on Windows than I am.