Micro-optimize rustdoc search index parsing #148522

yotamofek · 2025-11-05T10:55:57Z

This should pre-allocate the correct size for the slot vec. Not sure how much of a difference it'll make, but let's see.

rustbot · 2025-11-05T10:56:02Z

r? @GuillaumeGomez

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yotamofek · 2025-11-05T11:07:47Z

@bors try @rust-timer queue

…rom_string, r=<try> Micro-optimize rustdoc search index parsing

rust-bors · 2025-11-05T13:18:34Z

☀️ Try build successful (CI)
Build commit: 68a9c0e (68a9c0e6ecf9481452ec6e82f8b0675cd643fd63, parent: 8e0b68e63cd2b7b6d18474fe6f49df6fb1570c25)

rust-timer · 2025-11-06T03:49:46Z

Finished benchmarking commit (68a9c0e): comparison URL.

Overall result: no relevant changes - no action needed

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

@bors rollup=never
@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

Results (secondary 4.5%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	4.5%	[4.5%, 4.5%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Cycles

Results (primary -2.9%, secondary 3.4%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	6.1%	[5.2%, 7.0%]	2
Improvements ✅ (primary)	-2.9%	[-2.9%, -2.9%]	1
Improvements ✅ (secondary)	-2.1%	[-2.1%, -2.1%]	1
All ❌✅ (primary)	-2.9%	[-2.9%, -2.9%]	1

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 475.57s -> 474.667s (-0.19%)
Artifact size: 390.76 MiB -> 390.71 MiB (-0.01%)

yotamofek · 2025-11-14T22:26:29Z

Let's see perf after #147918

@bors try @rust-timer queue

I do think the code is nicer even if not more performant, so I think we should merge this regardless.

…rom_string, r=<try> Micro-optimize rustdoc search index parsing

rust-bors · 2025-11-15T00:42:08Z

☀️ Try build successful (CI)
Build commit: 76ad0a7 (76ad0a7f87b150391480a9e15093c0b10d36f182, parent: b6d7ff3aa71e48e2901b0900f8b5d98126b537ed)

rust-timer · 2025-11-15T02:01:57Z

Finished benchmarking commit (76ad0a7): comparison URL.

Overall result: ❌ regressions - please read the text below

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please do so in sufficient writing along with @rustbot label: +perf-regression-triaged. If not, please fix the regressions and do another perf run. If its results are neutral or positive, the label will be automatically removed.

@bors rollup=never
@rustbot label: -S-waiting-on-perf +perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	3.0%	[3.0%, 3.0%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	3.0%	[3.0%, 3.0%]	1

Max RSS (memory usage)

Results (primary 2.1%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	2.1%	[2.1%, 2.1%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.1%	[2.1%, 2.1%]	1

Cycles

Results (primary 2.8%, secondary -2.8%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	2.8%	[2.8%, 2.8%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.8%	[-2.8%, -2.8%]	1
All ❌✅ (primary)	2.8%	[2.8%, 2.8%]	1

Binary size

Results (primary 1.1%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	1.1%	[1.1%, 1.1%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.1%	[1.1%, 1.1%]	1

Bootstrap: 474.001s -> 474.341s (0.07%)
Artifact size: 388.67 MiB -> 388.68 MiB (0.00%)

yotamofek · 2025-11-15T08:40:33Z

(regression is spurious and probably unrelated, not even for "Doc" profile)

GuillaumeGomez · 2025-11-15T11:43:40Z

Code is shorter and no impact on perf so let's go. Thanks!

@bors r+ rollup

bors · 2025-11-15T11:43:43Z

📌 Commit ab769ec has been approved by GuillaumeGomez

It is now in the queue for this repository.

…_postings_from_string, r=GuillaumeGomez Micro-optimize rustdoc search index parsing This should pre-allocate the correct size for the `slot` vec. Not sure how much of a difference it'll make, but let's see.

Rollup of 10 pull requests Successful merges: - #148416 (`vec_recycle`: implementation) - #148522 (Micro-optimize rustdoc search index parsing) - #148827 (Stabilize vec_into_raw_parts) - #148832 (Bump library dependencies) - #148836 (tweak primitive reference docs) - #148859 (Fix overflow-checks test for RISC-V target) - #148886 (Add riscv64a23-unknown-linux-gnu to build-manifest TARGETS) - #148956 (re-enable wasm abi test) - #148963 (runtest.rs: remove redundant check) - #148968 (Add another *ExprWithBlock* test for `try` blocks) r? `@ghost` `@rustbot` modify labels: rollup

Rollup of 11 pull requests Successful merges: - #148416 (`vec_recycle`: implementation) - #148522 (Micro-optimize rustdoc search index parsing) - #148827 (Stabilize vec_into_raw_parts) - #148832 (Bump library dependencies) - #148836 (tweak primitive reference docs) - #148859 (Fix overflow-checks test for RISC-V target) - #148886 (Add riscv64a23-unknown-linux-gnu to build-manifest TARGETS) - #148956 (re-enable wasm abi test) - #148963 (runtest.rs: remove redundant check) - #148968 (Add another *ExprWithBlock* test for `try` blocks) - #148984 (chore: Update annotate-snippets to 0.12.9) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #148522 - yotamofek:pr/rustdoc/optimize-read_postings_from_string, r=GuillaumeGomez Micro-optimize rustdoc search index parsing This should pre-allocate the correct size for the `slot` vec. Not sure how much of a difference it'll make, but let's see.

Micro-optimize rustdoc search index parsing

ab769ec

rustbot assigned GuillaumeGomez Nov 5, 2025