Stream: git-wasmtime

Topic: wasmtime / PR #4584 Use a `SmallVec` for `ABIArg`s

Wasmtime GitHub notifications bot (Aug 02 2022 at 21:37):

fitzgen opened PR #4584 from abi-arg-small-vec to main:

Instead of a regular Vec.

These vectors are usually very small, for example here is the histogram of sizes
when running Sightglass's pulldown-cmark benchmark:

;; Number of samples = 10332
;; Min = 0
;; Max = 11
;;
;; Mean = 2.496128532713901
;; Standard deviation = 2.2859559855427243
;; Variance = 5.225594767838607
;;
;; Each ∎ is a count of 62
;;
 0 ..  1 [ 3134 ]: ∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎
 1 ..  2 [ 2032 ]: ∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎
 2 ..  3 [  159 ]: ∎∎
 3 ..  4 [  838 ]: ∎∎∎∎∎∎∎∎∎∎∎∎∎
 4 ..  5 [  970 ]: ∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎
 5 ..  6 [ 2566 ]: ∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎
 6 ..  7 [  303 ]: ∎∎∎∎
 7 ..  8 [  272 ]: ∎∎∎∎
 8 ..  9 [   40 ]:
 9 .. 10 [   18 ]:

By using a SmallVec with capacity of 6 we avoid the vast majority of heap
allocations and get some nice benchmark wins of up to ~1.11x faster compilation.

<h3>Sightglass Benchmark Results</h3>

compilation :: nanoseconds :: benchmarks/spidermonkey/benchmark.wasm

  Δ = 340361395.90 ± 63384608.15 (confidence = 99%)

  main.so is 0.88x to 0.92x faster than smallvec.so!
  smallvec.so is 1.09x to 1.13x faster than main.so!

  [3101467423 3425524333.41 4060621653] main.so
  [2820915877 3085162937.51 3375167352] smallvec.so

compilation :: cycles :: benchmarks/spidermonkey/benchmark.wasm

  Δ = 988446098.59 ± 184075718.89 (confidence = 99%)

  main.so is 0.88x to 0.92x faster than smallvec.so!
  smallvec.so is 1.09x to 1.13x faster than main.so!

  [9006994951 9948091070.66 11792481990] main.so
  [8192243090 8959644972.07 9801848982] smallvec.so

compilation :: nanoseconds :: benchmarks/bz2/benchmark.wasm

  Δ = 7854567.87 ± 2215491.16 (confidence = 99%)

  main.so is 0.89x to 0.94x faster than smallvec.so!
  smallvec.so is 1.07x to 1.12x faster than main.so!

  [80354527 93864666.76 119789198] main.so
  [77554917 86010098.89 94726994] smallvec.so

compilation :: cycles :: benchmarks/bz2/benchmark.wasm

  Δ = 22810509.85 ± 6434024.63 (confidence = 99%)

  main.so is 0.89x to 0.94x faster than smallvec.so!
  smallvec.so is 1.07x to 1.12x faster than main.so!

  [233358190 272593088.57 347880715] main.so
  [225227821 249782578.72 275097380] smallvec.so

compilation :: nanoseconds :: benchmarks/pulldown-cmark/benchmark.wasm

  Δ = 10849521.41 ± 4324757.85 (confidence = 99%)

  main.so is 0.90x to 0.96x faster than smallvec.so!
  smallvec.so is 1.04x to 1.10x faster than main.so!

  [133875427 156859544.47 222455440] main.so
  [126073854 146010023.06 181611647] smallvec.so

compilation :: cycles :: benchmarks/pulldown-cmark/benchmark.wasm

  Δ = 31508176.97 ± 12559561.91 (confidence = 99%)

  main.so is 0.90x to 0.96x faster than smallvec.so!
  smallvec.so is 1.04x to 1.10x faster than main.so!

  [388788638 455536988.31 646034523] main.so
  [366132033 424028811.34 527419755] smallvec.so

<!--

Please ensure that the following steps are all taken care of before submitting
the PR.

• [ ] This has been discussed in issue #..., or if not, please tell us why
  here.

• [ ] A short description of what this does, why it is needed; if the
  description becomes long, the matter should probably be discussed in an issue
  first.

• [ ] This PR contains test cases, if meaningful.

• [ ] A reviewer from the core maintainer team has been assigned for this PR.
  If you don't know who could review this, please indicate so. The list of
  suggested reviewers on the right can help you.

Please ensure all communication adheres to the code of conduct.
-->

Wasmtime GitHub notifications bot (Aug 02 2022 at 21:37):

fitzgen requested cfallin for a review on PR #4584.

Wasmtime GitHub notifications bot (Aug 02 2022 at 21:41):

cfallin submitted PR review.

Wasmtime GitHub notifications bot (Aug 02 2022 at 21:41):

cfallin submitted PR review.

Wasmtime GitHub notifications bot (Aug 02 2022 at 21:41):

cfallin created PR review comment:

Can we put a type ABIArgVec SmallVec<[ABIArg; 6]> in machinst::abi_impl then use it here (and ABIArgVec::new()` below)? That would allow us to tweak the size later more easily without updating each backend.

Wasmtime GitHub notifications bot (Aug 02 2022 at 21:41):

cfallin edited PR review comment.

Wasmtime GitHub notifications bot (Aug 02 2022 at 21:52):

fitzgen updated PR #4584 from abi-arg-small-vec to main.

Wasmtime GitHub notifications bot (Aug 02 2022 at 21:57):

cfallin submitted PR review.

Wasmtime GitHub notifications bot (Aug 02 2022 at 21:57):

cfallin created PR review comment:

little nit: we can use ABIArgVec here too I think...

Wasmtime GitHub notifications bot (Aug 02 2022 at 21:58):

fitzgen updated PR #4584 from abi-arg-small-vec to main.

Wasmtime GitHub notifications bot (Aug 02 2022 at 21:58):

fitzgen submitted PR review.

Wasmtime GitHub notifications bot (Aug 02 2022 at 21:58):

fitzgen created PR review comment:

Thanks! missed that one

Wasmtime GitHub notifications bot (Aug 02 2022 at 22:53):

fitzgen merged PR #4584.

Last updated: Nov 22 2024 at 17:03 UTC