Environment.ProcessorCount returns bad value in NUMA environment #41902
Description
This may be entirely attributable to #13691 but I'm not sure, so I'm filing it.
Description
On a Standard_F72s_v2 VM, which has 72 logical processors, Environment.ProcessorCount returns 36.
using System;
namespace proccount
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine(System.Environment.ProcessorCount);
}
}
}$ dotnet run
36Configuration
$ dotnet --info
.NET SDK (reflecting any global.json):
Version: 5.0.100-rc.1.20452.6
Commit: 31c7208879
Runtime Environment:
OS Name: Windows
OS Version: 10.0.19041
OS Platform: Windows
RID: win10-x64
Base Path: C:\Users\raines.NTDEV\Downloads\dotnet-sdk-5.0.100-rc.1.20452.6-win-x64\sdk\5.0.100-rc.1.20452.6\
Host (useful for support):
Version: 5.0.0-rc.1.20451.14
Commit: 38017c3935
.NET SDKs installed:
5.0.100-rc.1.20452.6 [C:\Users\raines.NTDEV\Downloads\dotnet-sdk-5.0.100-rc.1.20452.6-win-x64\sdk]
.NET runtimes installed:
Microsoft.AspNetCore.App 5.0.0-rc.1.20451.17 [C:\Users\raines.NTDEV\Downloads\dotnet-sdk-5.0.100-rc.1.20452.6-win-x64\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 5.0.0-rc.1.20451.14 [C:\Users\raines.NTDEV\Downloads\dotnet-sdk-5.0.100-rc.1.20452.6-win-x64\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 5.0.0-rc.1.20452.2 [C:\Users\raines.NTDEV\Downloads\dotnet-sdk-5.0.100-rc.1.20452.6-win-x64\shared\Microsoft.WindowsDesktop.App]Regression?
Not from 3.1.
Other information
I think what's being returned is the number of available cores in the current NUMA node:
That condition looks backward to me: if you can use use all CPU groups, shouldn't you do so rather than only the current group? But maybe I'm misunderstanding the intention.