Add support for IBM Z architecture

[adamsitnik]

.NET is going to support a new architecture (dotnet/runtime#52909), we should do so as well.

namespace System.Runtime.InteropServices
{
    public enum Architecture
    {
        X86,
        X64,
        Arm,
        Arm64,
        Wasm,
+       S390x,
    }
}

More details: dotnet/runtime#52906

@uweigand some context: BenchmarkDotNet is the most popular microbenchmark harness in the .NET ecosystem. We already support x64, x86, ARM64, and ARM and would love to support S390x as well. When can we expect that the new architecture will be fully supported by .NET SDK and MSBuild?

[uweigand]

Hi @adamsitnik, thanks for reaching out! We'd certainly be interested in having BenchmarkDotNet support for s390x as well. In fact, a colleague has started to investigate what it would take to get it to run, and did run into a number of dependency issues. I'll get back to him on that.

As to timelines, in general our goal would be to to have .NET support for s390x in place throughout the core runtime & SDK in time for the .NET 6 release. I have most of that already running with the use of extra out-of-tree patches, and we've started the process of getting everything merged upstream -- let's see how quickly this goes. It would be ideal if we had BenchmarkDotNet operational significantly before the release, of course, so we can already use it to evaluate and improve the performance users are going to see in the release.

[adamsitnik]

@uweigand that is really great to hear!

I've sent #1712 which in theory is all we need.

Our CI pushes a preview NuGet package for every succesful build to the following NuGet feed:

<packageSources>
  <add key="bdn-ci" value="https://ci.appveyor.com/nuget/benchmarkdotnet" />
</packageSources>

Once there is a .NET SDK that can build and run .NET on S390x you should be able to download a preview package from our CI feed and give it a try. Please let me know when you get there. I would be very happy to help!

[uweigand]

Thanks, that looks excellent! We'll definitely give it a try.

[adamsitnik]

this CI build got green and it pushed 0.13.0.1552 NuGet to the feed

[stefan-sf-ibm]

@adamsitnik I gave 0.13.0.1552 a quick try and ran a couple of tests successfully. Thanks for the updated package!

[adamsitnik]

@stefan-sf-ibm thanks for letting me know!

[stefan-sf-ibm]

@adamsitnik I did a couple of further tests using .NET Performance and noticed that all generated BenchmarkDotNet.Autogenerated.csproj files contain

<PlatformTarget>S390x</PlatformTarget>

which leads to an exception here.

So far there exists no System.Reflection.PortableExecutable.Machine.S390x in runtimelab and I'm not sure whether we want to add this or not. Having a look at System.Private.CoreLib.csproj we have

<PropertyGroup Condition="'$(Platform)' == 's390x'">
  <PlatformTarget>AnyCPU</PlatformTarget>
  <DefineConstants>$(DefineConstants);TARGET_S390X;BIGENDIAN</DefineConstants>
</PropertyGroup>

So I'm wondering whether it would be appropriate to also set the platform target to AnyCPU for S390x for those generated BenchmarkDotNet.Autogenerated.csproj files?

[adamsitnik]

@stefan-sf-ibm Could you please try to extend this config definition with:

.WithPlatform(Environments.Platform.AnyCpu)

and see if it helps?

I wonder what should be the proper solution: wait until Roslyn adds s390x to their supported platform list and keep using

<PlatformTarget>S390x</PlatformTarget>

Or always set the PlatformTarget to AnyCpu for IBM Z?

[uweigand]

@adamsitnik I'm wondering what the benefits of setting PlatformTarget are in the first place. According to the Roslyn docs, the only difference is that the binary is marked as limited to run only on the selected platform. If this is true, what do we gain from using the setting here? Or am I missing something?

[adamsitnik]

I'm wondering what the benefits of setting PlatformTarget are in the first place.

Two things come to my mind:

• If exe is built as AnyCpu, on Windows it can be run both by 32bit and 64bit dotnet.exe. I guess it makes no sense for S390x as it is only 64bit?
• PlatformTarget might be taken under consideration when running dotnet restore for NuGet packages with native dependencies.

But to be honest with you I am not 100% sure about the restore. @eerhardt could you confirm?