const vs. non-const widget build benchmark #148261

goderbauer · 2024-05-13T21:36:34Z

This benchmark illustrates the impact that const'ness has on widget build times by building a widget tree with all const-widgets and then building the same widget tree without any const'ness. Local testing with this benchmark running on a Moto G4 shows that const'ness is 13-16% faster.

I'd like to check this benchmark in because the question of how important widget const'ness is comes up every so often. With this benchmark we have up-to-date data to point people to.

LongCatIsLooong · 2024-05-14T14:16:12Z

dev/benchmarks/microbenchmarks/lib/building/const_vs_non_const_bench.dart

+    while (elapsed < kBenchmarkTime) {
+      watch.reset();
+      watch.start();
+      rootWidget.markNeedsBuild();


Why is markNeedsBuild also timed?

That's what we do in our other build benchmarks, which I used for a template for this one.

LongCatIsLooong · 2024-05-14T14:51:13Z

dev/benchmarks/microbenchmarks/lib/building/const_vs_non_const_bench.dart

+      iterations += 1;
+      elapsed += Duration(microseconds: watch.elapsedMicroseconds);
+      values.add(watch.elapsedMicroseconds.toDouble());
+      print(values.last);


nit: this can be a bit spammy, maybe add this to printer?

Ups, I just forgot to remove this after doing some debugging.

LongCatIsLooong · 2024-05-14T14:59:01Z

dev/benchmarks/microbenchmarks/lib/building/const_vs_non_const_bench.dart

+
+  @override
+  Widget build(BuildContext context) {
+    return const SizedBox(


this benchmark running on a Moto G4 shows that const'ness is 5-7% faster

Rebuilding 30+ elements, plus overhead is only 5-7% slower than rebuilding 1 element, plus overhead, so it looks like the majority of the cpu time is spent on the overhead? Given that there's no relayout or repaint maybe instead of pumpBenchmark we should run owner.buildScope to increase the signal to noise ratio?

Let's see what the benchmark numbers will look like in the lab and we can then tweak this if it is too noisy.

LongCatIsLooong · 2024-05-14T16:07:54Z

dev/benchmarks/microbenchmarks/lib/building/const_vs_non_const_bench.dart

+  );
+  printer.addResult(
+    description: 'const speed-up (vs. non-const)',
+    value: (1.0 - (constMean / nonConstMean)) * 100,


Hmm if an operation used to take 10s but now takes 5s I thought that should be called a 100% speed up? But with this formula that would only be a 50% speedup?

Oh, right. I'll fix this up.

Done. Can you check my updated math?

LongCatIsLooong

still LGTM

…#148261)

flutter/flutter@0d22d91...00425ef 2024-05-17 engine-flutter-autoroll@skia.org Roll Flutter Engine from d575e511f9e5 to a19d3722922d (2 revisions) (flutter/flutter#148534) 2024-05-17 engine-flutter-autoroll@skia.org Roll Flutter Engine from 8d1a1d8d7b48 to d575e511f9e5 (5 revisions) (flutter/flutter#148529) 2024-05-17 engine-flutter-autoroll@skia.org Manual roll Flutter Engine from 6fa734d68688 to 8d1a1d8d7b48 (8 revisions) (flutter/flutter#148528) 2024-05-17 32538273+ValentinVignal@users.noreply.github.com Add test for material_banner.0.dart and material_banner.1.dart (flutter/flutter#148452) 2024-05-17 nate.w5687@gmail.com `switch` statement cleanup (flutter/flutter#148382) 2024-05-16 goderbauer@google.com const vs. non-const widget build benchmark (flutter/flutter#148261) 2024-05-16 49699333+dependabot[bot]@users.noreply.github.com Bump actions/checkout from 4.1.5 to 4.1.6 (flutter/flutter#148516) 2024-05-16 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Roll Flutter Engine from 6fa734d68688 to 1850def2ccff (1 revision) (#148507)" (flutter/flutter#148517) 2024-05-16 stuartmorgan@google.com Add PrivacyInfo.xcprivacy to plugin template (flutter/flutter#148485) 2024-05-16 stuartmorgan@google.com Fix iOS reference in macOS Cocoapods error (flutter/flutter#148506) 2024-05-16 engine-flutter-autoroll@skia.org Roll Flutter Engine from 6fa734d68688 to 1850def2ccff (1 revision) (flutter/flutter#148507) 2024-05-16 engine-flutter-autoroll@skia.org Roll Flutter Engine from 460df6caef0e to 6fa734d68688 (4 revisions) (flutter/flutter#148500) 2024-05-16 nate.w5687@gmail.com Enhanced enum features for `AnimationStatus` (flutter/flutter#147801) 2024-05-16 matej.knopp@gmail.com [macOS] codesign native assets during embed (flutter/flutter#148310) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC rmistry@google.com,stuartmorgan@google.com on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

…r#6753) flutter/flutter@0d22d91...00425ef 2024-05-17 engine-flutter-autoroll@skia.org Roll Flutter Engine from d575e511f9e5 to a19d3722922d (2 revisions) (flutter/flutter#148534) 2024-05-17 engine-flutter-autoroll@skia.org Roll Flutter Engine from 8d1a1d8d7b48 to d575e511f9e5 (5 revisions) (flutter/flutter#148529) 2024-05-17 engine-flutter-autoroll@skia.org Manual roll Flutter Engine from 6fa734d68688 to 8d1a1d8d7b48 (8 revisions) (flutter/flutter#148528) 2024-05-17 32538273+ValentinVignal@users.noreply.github.com Add test for material_banner.0.dart and material_banner.1.dart (flutter/flutter#148452) 2024-05-17 nate.w5687@gmail.com `switch` statement cleanup (flutter/flutter#148382) 2024-05-16 goderbauer@google.com const vs. non-const widget build benchmark (flutter/flutter#148261) 2024-05-16 49699333+dependabot[bot]@users.noreply.github.com Bump actions/checkout from 4.1.5 to 4.1.6 (flutter/flutter#148516) 2024-05-16 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Roll Flutter Engine from 6fa734d68688 to 1850def2ccff (1 revision) (#148507)" (flutter/flutter#148517) 2024-05-16 stuartmorgan@google.com Add PrivacyInfo.xcprivacy to plugin template (flutter/flutter#148485) 2024-05-16 stuartmorgan@google.com Fix iOS reference in macOS Cocoapods error (flutter/flutter#148506) 2024-05-16 engine-flutter-autoroll@skia.org Roll Flutter Engine from 6fa734d68688 to 1850def2ccff (1 revision) (flutter/flutter#148507) 2024-05-16 engine-flutter-autoroll@skia.org Roll Flutter Engine from 460df6caef0e to 6fa734d68688 (4 revisions) (flutter/flutter#148500) 2024-05-16 nate.w5687@gmail.com Enhanced enum features for `AnimationStatus` (flutter/flutter#147801) 2024-05-16 matej.knopp@gmail.com [macOS] codesign native assets during embed (flutter/flutter#148310) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC rmistry@google.com,stuartmorgan@google.com on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

goderbauer · 2024-05-23T16:24:18Z

Reason for revert: #148845

auto-submit · 2024-05-23T16:24:59Z

Time to revert pull request flutter/flutter/148261 has elapsed.
You need to open the revert manually and process as a regular pull request.

This reverts commit c4ad1dc.

Reverts #148261 For some reason, the benchmark is flaky only on iOS. Android runs are fine. See #148845. Closes #148845.

cedvdb · 2024-05-28T15:15:52Z

This does not imply any significant impact on a real app. It shows something, just not sure that this something is relevant to flutter users.

goderbauer requested a review from LongCatIsLooong May 13, 2024 21:36

LongCatIsLooong approved these changes May 14, 2024

View reviewed changes

LongCatIsLooong reviewed May 14, 2024

View reviewed changes

goderbauer requested a review from LongCatIsLooong May 15, 2024 20:14

LongCatIsLooong approved these changes May 15, 2024

View reviewed changes

goderbauer added 3 commits May 15, 2024 13:40

const vs. non-const widget build benchmark

d100401

remove print

caa2c1a

fix math

b177353

goderbauer force-pushed the constBenchmark branch from 76e0814 to b177353 Compare May 15, 2024 20:40

goderbauer added the autosubmit Merge PR when tree becomes green via auto submit App label May 16, 2024

auto-submit bot merged commit c4ad1dc into flutter:master May 16, 2024
139 checks passed

engine-flutter-autoroll mentioned this pull request May 17, 2024

Roll Flutter from 0d22d9101aac to 7f32df42187c (13 revisions) flutter/packages#6752

Closed

engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request May 17, 2024

c4ad1dc1e const vs. non-const widget build benchmark (flutter/flutter…

edff238

…#148261)

engine-flutter-autoroll mentioned this pull request May 17, 2024

Roll Flutter from 0d22d9101aac to 00425ef1be26 (14 revisions) flutter/packages#6753

Merged

engine-flutter-autoroll added a commit to engine-flutter-autoroll/packages that referenced this pull request May 17, 2024

c4ad1dc1e const vs. non-const widget build benchmark (flutter/flutter…

69fa24a

…#148261)

dxvid-pts mentioned this pull request May 17, 2024

Feature Request: Add comptime Functionality Similar to ZigLang to Dart dart-lang/language#3818

Open

vashworth mentioned this pull request May 23, 2024

Mac_ios microbenchmarks_ios is 8.08% flaky #148845

Closed

goderbauer deleted the constBenchmark branch May 23, 2024 16:23

goderbauer added the revert Autorevert PR (with "Reason for revert:" comment) label May 23, 2024

auto-submit bot removed the revert Autorevert PR (with "Reason for revert:" comment) label May 23, 2024

goderbauer added a commit that referenced this pull request May 23, 2024

Revert "const vs. non-const widget build benchmark (#148261)"

0a54883

This reverts commit c4ad1dc.

goderbauer mentioned this pull request May 23, 2024

Revert "const vs. non-const widget build benchmark" #148970

Merged

auto-submit bot pushed a commit that referenced this pull request May 23, 2024

Revert "const vs. non-const widget build benchmark" (#148970)

6cdb632

Reverts #148261 For some reason, the benchmark is flaky only on iOS. Android runs are fine. See #148845. Closes #148845.

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

const vs. non-const widget build benchmark #148261

const vs. non-const widget build benchmark #148261

goderbauer commented May 13, 2024 •

edited

LongCatIsLooong May 14, 2024

goderbauer May 14, 2024

LongCatIsLooong May 14, 2024

goderbauer May 14, 2024

LongCatIsLooong May 14, 2024

goderbauer May 14, 2024

LongCatIsLooong May 14, 2024

goderbauer May 14, 2024

goderbauer May 15, 2024

LongCatIsLooong left a comment

goderbauer commented May 23, 2024

auto-submit bot commented May 23, 2024

cedvdb commented May 28, 2024 •

edited

const vs. non-const widget build benchmark #148261

const vs. non-const widget build benchmark #148261

Conversation

goderbauer commented May 13, 2024 • edited

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

LongCatIsLooong left a comment

Choose a reason for hiding this comment

goderbauer commented May 23, 2024

auto-submit bot commented May 23, 2024

cedvdb commented May 28, 2024 • edited

goderbauer commented May 13, 2024 •

edited

cedvdb commented May 28, 2024 •

edited