mpk: allow benchmarking MPK#7787
Merged
Merged
Conversation
This change takes advantage of the `WASMTIME_TEST_FORCE_MPK` environment variable to force its use in the `call.rs` benchmarks. I see differences in several cases when running: ```console $ taskset --cpu-list 0-15 cargo bench -- async $ WASMTIME_TEST_FORCE_MPK=1 taskset --cpu-list 0-15 cargo bench -- async ``` To properly isolate the MPK effects, this adds a `sync-pool` option (`IsAsync::NoPooling`).
After noticing some minor effects with this PKRU read, I chose to avoid it unless logging is enabled. A perfectly valid alternative would be to remove the logging altogether, but I have found this very helpful when trying to troubleshoot MPK issues.
To avoid any unnecessary call overhead, we hint to the compiler that `pkru::read` and `pkru::write` should be inlined.
alexcrichton
approved these changes
Jan 18, 2024
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
These changes allow one to measure the effect of MPK on WebAssembly boundary crossings (guest-host and vice-versa). I also includes some small but distracting bits that affect the measured overhead.