Wasmtime GitHub notifications bot (Apr 06 2026 at 19:47): Wasmtime GitHub notifications bot (Apr 06 2026 at 19:47):fitzgen opened PR #12974 from fitzgen:drc-runtime-improvements to bytecodealliance:main:
Depends on https://github.com/bytecodealliance/wasmtime/pull/12969
See each commit message for details.
More coming soon after this.
Wasmtime GitHub notifications bot (Apr 06 2026 at 19:47):fitzgen requested alexcrichton for a review on PR #12974.
Wasmtime GitHub notifications bot (Apr 06 2026 at 19:47):fitzgen requested wasmtime-compiler-reviewers for a review on PR #12974.
Wasmtime GitHub notifications bot (Apr 06 2026 at 19:47):fitzgen requested wasmtime-core-reviewers for a review on PR #12974.
Wasmtime GitHub notifications bot (Apr 06 2026 at 20:24):fitzgen updated PR #12974.
Wasmtime GitHub notifications bot (Apr 06 2026 at 23:53):github-actions[bot] added the label wasmtime:ref-types on PR #12974.
Wasmtime GitHub notifications bot (Apr 06 2026 at 23:53):github-actions[bot] added the label wasmtime:api on PR #12974.
Wasmtime GitHub notifications bot (Apr 06 2026 at 23:54):github-actions[bot] commented on PR #12974:
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Wasmtime GitHub notifications bot (Apr 07 2026 at 20:56):alexcrichton submitted PR review:
I need to spend more time looking at Combine dec_ref, trace, and dealloc into single-pass loop but this is one thing I noticed. The later commits seem fine though.
This is another case though where in-wasm GC allocation, GC mark/sweep, etc, would I suspect remove a huge amount of the overhead since the host has to dance around "the heap could be corrupt at any time" which loses a lot of perf I believe. I realize that's a big undertaking, but we may want to discuss more seriously in a meeting at some point if it's table stakes or not for shipping gc.
Wasmtime GitHub notifications bot (Apr 07 2026 at 20:56):alexcrichton created PR review comment:
This seems like it's a bit of a poor-man's hash map here. Since this is already using a hash map, what's the performance of using a custom hasher where the hash of
VMSharedTypeIndexis just its bit value?
Wasmtime GitHub notifications bot (Apr 07 2026 at 21:19):fitzgen commented on PR #12974:
I realize that's a big undertaking, but we may want to discuss more seriously in a meeting at some point if it's table stakes or not for shipping gc.
Happy to discuss at a meeting, I'll add an item, but I find it super surprising that we would even entertain the idea of blocking enabling the GC proposal by default on self-hosting the free list (or even worse from a time-to-shipping perspective: self-hosting the whole collector runtime).
Wasmtime GitHub notifications bot (Apr 08 2026 at 16:45):alexcrichton submitted PR review:
@fitzgen @cfallin and I talked a bit more about GC things today, and we'll summarize our thinking at tomorrow's Wasmtime meeting as well.
Wasmtime GitHub notifications bot (Apr 08 2026 at 23:34):fitzgen submitted PR review.
Wasmtime GitHub notifications bot (Apr 08 2026 at 23:34):fitzgen created PR review comment:
Good call. I reverted that commit and things got ~10% slower, but then I added a custom nop-hasher and they got ~3% faster from where we started. So seems like the nop-hasher is the way to go! Will push momentarily.
Wasmtime GitHub notifications bot (Apr 08 2026 at 23:44):fitzgen updated PR #12974.
Wasmtime GitHub notifications bot (Apr 08 2026 at 23:45):fitzgen has enabled auto merge for PR #12974.
Wasmtime GitHub notifications bot (Apr 08 2026 at 23:58):fitzgen added PR #12974 A handful of optimizations for the DRC collector to the merge queue.
Wasmtime GitHub notifications bot (Apr 09 2026 at 00:22):github-merge-queue[bot] removed PR #12974 A handful of optimizations for the DRC collector from the merge queue.
Wasmtime GitHub notifications bot (Apr 09 2026 at 14:35):fitzgen updated PR #12974.
Wasmtime GitHub notifications bot (Apr 09 2026 at 14:35):fitzgen has enabled auto merge for PR #12974.
Wasmtime GitHub notifications bot (Apr 09 2026 at 14:48):fitzgen added PR #12974 A handful of optimizations for the DRC collector to the merge queue.
Wasmtime GitHub notifications bot (Apr 09 2026 at 15:14):github-merge-queue[bot] removed PR #12974 A handful of optimizations for the DRC collector from the merge queue.
Wasmtime GitHub notifications bot (Apr 09 2026 at 18:49):fitzgen has enabled auto merge for PR #12974.
Wasmtime GitHub notifications bot (Apr 09 2026 at 18:49):fitzgen updated PR #12974.
Wasmtime GitHub notifications bot (Apr 09 2026 at 19:02):fitzgen added PR #12974 A handful of optimizations for the DRC collector to the merge queue.
Wasmtime GitHub notifications bot (Apr 09 2026 at 19:20):alexcrichton commented on PR #12974:
I pulled this out of the queue manually due to the failure at https://github.com/bytecodealliance/wasmtime/actions/runs/24208166925/job/70669519553
Wasmtime GitHub notifications bot (Apr 09 2026 at 19:21):alexcrichton removed PR #12974 A handful of optimizations for the DRC collector from the merge queue.
Wasmtime GitHub notifications bot (Apr 09 2026 at 21:05):fitzgen updated PR #12974.
Wasmtime GitHub notifications bot (Apr 09 2026 at 21:05):fitzgen has enabled auto merge for PR #12974.
Wasmtime GitHub notifications bot (Apr 09 2026 at 21:18):fitzgen added PR #12974 A handful of optimizations for the DRC collector to the merge queue.
Wasmtime GitHub notifications bot (Apr 09 2026 at 21:44):github-merge-queue[bot] removed PR #12974 A handful of optimizations for the DRC collector from the merge queue.
Wasmtime GitHub notifications bot (Apr 10 2026 at 19:18):fitzgen updated PR #12974.
Wasmtime GitHub notifications bot (Apr 10 2026 at 19:18):fitzgen has enabled auto merge for PR #12974.
Wasmtime GitHub notifications bot (Apr 10 2026 at 19:22):fitzgen updated PR #12974.
Wasmtime GitHub notifications bot (Apr 10 2026 at 19:49):fitzgen updated PR #12974.
Wasmtime GitHub notifications bot (Apr 10 2026 at 20:27):fitzgen updated PR #12974.
Wasmtime GitHub notifications bot (Apr 10 2026 at 21:27):fitzgen updated PR #12974.
Wasmtime GitHub notifications bot (Apr 10 2026 at 21:41):fitzgen added PR #12974 A handful of optimizations for the DRC collector to the merge queue.
Wasmtime GitHub notifications bot (Apr 10 2026 at 22:07):fitzgen removed PR #12974 A handful of optimizations for the DRC collector from the merge queue.
Wasmtime GitHub notifications bot (Apr 10 2026 at 22:07):fitzgen merged PR #12974.
Last updated: Apr 12 2026 at 23:10 UTC