Introduce System.Runtime.TieredPGO knob #26350
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I couldn't figure out the best area label to add to this PR. If you have write-permissions please help me learn by adding exactly one area label. |
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Um.. I am not sure who to ask for review here, perhaps @eerhardt? |
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Can you also add to the test to ensure the MSBuild settings are flown to the runtimeconfig.json file? See #12362 for an example of where to change the tests. |
| @@ -487,6 +487,10 @@ Copyright (c) .NET Foundation. All rights reserved. | |||
| Condition="'$(TieredCompilationQuickJitForLoops)' != ''" | |||
| Value="$(TieredCompilationQuickJitForLoops)" /> | |||
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| <RuntimeHostConfigurationOption Include="System.Runtime.TieredPGO" | |||
| Condition="'$(TieredPGO)' != ''" | |||
| Value="$(TieredPGO)" /> | |||
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Question: Is PGO the term we use in docs when discussing this feature with customers? These strings System.Runtime.TieredPGO and TieredPGO are basically public APIs, so we have to be happy with the names we are picking here. It would be a breaking change to rename them later.
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@eerhardt We've been advertising DOTNET_TieredPGO environment variable since .NET 6.0 e.g.
https://devblogs.microsoft.com/dotnet/announcing-net-6/#dynamic-pgo (I was collecting feedback from users here: https://gist.github.com/EgorBo/dc181796683da3d905a5295bfd3dd95b) - it perfectly aligns with DOTNET_TieredCompilation which maps to <TieredCompilation>true</TieredCompilation> here.
We considered other names/options but a simple boolean property seems to be the best and simple. Eventually, we plan to enable it by default I guess (e.g. in .NET 8.0). For .NET 7.0 we just want our customers to be able to easily enable it to try the feature
Related dotnet/runtime PR: dotnet/runtime#71438
The idea is to introduce a configuration switch similar to
TieredCompilationto expose a config switch forTieredPGO. It's done because many of our first/third parties are interested in trying Dynamic PGO and currently it's only possible withDOTNET_TieredPGO=1env. variable defined in the execution process.With this PR and the related SDK change customers will be able to turn it on (it's off by default) via MSBUILD or JSON config just like TieredCompilation, e.g.: