.NET 10 P5 Runtime #9912
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.NET 10 P5 Runtime #9912
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jamesmontemagno
requested review from
rbhanda,
leecow and
victorisr
as code owners
jamesmontemagno
requested review from
richlander,
ericstj,
AndyAyersMS and
amanasifkhalid
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Added some JIT notes, along with the GC write barrier improvements on arm64. cc @dotnet/jit-contrib, @AndyAyersMS @kunalspathak I could use a fact check on these -- thanks! |
AndyAyersMS
approved these changes
Jun 6, 2025
kunalspathak
reviewed
Jun 7, 2025
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| The .NET garbage collector (GC) is generational, meaning it separates live objects by age to improve collection performance. The GC collects younger generations more often under the assumption that long-lived objects are less likely to be unreferenced (or "dead") at any given time. However, suppose an old object starts referencing a young object; the GC needs to know it cannot collect the young object, but needing to scan older objects to collect a young object defeats the performance gains of a generational GC. | ||
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| To solve this problem, the JIT inserts write barriers before object reference updates to keep the GC informed. On x64, the runtime can dynamically switch between write barrier implementations to balance write speeds and collection efficiency, depending on the GC's configuration. [dotnet/runtime #111636](https://github.com/dotnet/runtime/pull/111636) brings this functionality to ARM64 as well. In particular, the new default write barrier implementation on ARM64 handles GC regions more precisely, improving collection performance at slight expense to write barrier throughput: Our benchmarks show GC pause improvements from eight to over twenty percent with the new workstation GC defaults. |
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with the new workstation GC defaults
It is also applicable even for server GC, not just workstation GC.
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