[release/7.0] Disable mark phase prefetching for segments #78925
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Backport of #78803 to release/7.0
/cc @PeterSolMS
Customer Impact
Idea behind this change is to give customers a workaround if they encounter issues with the GC changes in .NET Core 7.0. One change was the introduction of mark phase prefetching, so this change disables this for segments. Thus, when customers switch to clrg.dll as their GC, they will have behavior as close as possible to .NET Core 6.0.
Testing
Ran GCPerfSim scenarios, inspect generated code to ensure the right thing is happening both with and without mark phase prefetch.
Risk
Low, because there is no change for the GC in coreclr.dll, and the GC in clrgc.dll disables a new feature in 7.0.
IMPORTANT: Is this backport for a servicing release? If so and this change touches code that ships in a NuGet package, please make certain that you have added any necessary package authoring and gotten it explicitly reviewed.