Allow out of order dep graph node encoding #139756

Zoxc · 2025-04-13T17:33:10Z

This allows out of order dep graph node encoding by also encoding the index instead of using the file node order as the index.

MemEncoder is also brought back to life and used for encoding.

Both of these are done to enable thread-local encoding of dep graph nodes.

This is based on #139636.

rustbot · 2025-04-13T17:33:15Z

r? @davidtwco

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Zoxc · 2025-04-13T19:47:03Z

@bors try @rust-timer queue

Allow out of order dep graph node encoding This allows out of order dep graph node encoding by also encoding the index instead of using the file node order as the index. `MemEncoder` is also brought back to life and used for encoding. Both of these are done to enable thread-local encoding of dep graph nodes. This is based on rust-lang#139636.

bors · 2025-04-13T19:48:14Z

⌛ Trying commit 3269f5a with merge f1a6b16...

Zoxc · 2025-04-13T19:48:42Z

Local results, excluding #139636:

Benchmark	Before	After		Before	After		Before	After
Benchmark	Time	Time	%	Physical Memory	Physical Memory	%	Committed Memory	Committed Memory	%
🟣 clap:check:unchanged	0.3029s	0.3049s	0.66%	96.91 MiB	98.21 MiB	💔 1.34%	168.23 MiB	169.72 MiB	0.88%
🟣 hyper:check:unchanged	0.1204s	0.1214s	0.86%	61.82 MiB	62.16 MiB	0.55%	125.12 MiB	125.55 MiB	0.34%
🟣 regex:check:unchanged	0.2250s	0.2263s	0.58%	78.21 MiB	79.14 MiB	💔 1.19%	145.66 MiB	146.64 MiB	0.68%
🟣 syn:check:unchanged	0.4940s	0.4974s	0.69%	118.79 MiB	120.64 MiB	💔 1.55%	193.58 MiB	195.58 MiB	💔 1.03%
Total	1.1424s	1.1501s	0.68%	355.74 MiB	360.16 MiB	💔 1.24%	632.59 MiB	637.48 MiB	0.77%
Summary	1.0000s	1.0070s	0.70%	1 byte	1.01 bytes	💔 1.16%	1 byte	1.01 bytes	0.73%

Use thread local dep graph encoding This adds thread local encoding of dep graph nodes. Each thread has a `MemEncoder` that gets flushed to the global `FileEncoder` when it exceeds 64 kB. Each thread also has a local cache of dep indices. This means there can now be empty gaps in `SerializedDepGraph`. Indices are marked green and also allocated by the new atomic operation `DepNodeColorMap::try_mark_green` as the encoder lock is removed. This is based on rust-lang#139636 and rust-lang#139756.

bors · 2025-04-13T21:58:26Z

☀️ Try build successful - checks-actions
Build commit: f1a6b16 (f1a6b1636dabcb29e33a88e8b3a9b2817d78286d)

rust-timer · 2025-04-14T00:12:01Z

Finished benchmarking commit (f1a6b16): comparison URL.

Overall result: ❌✅ regressions and improvements - BENCHMARK(S) FAILED

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

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

❗ ❗ ❗ ❗ ❗
Warning ⚠️: The following benchmark(s) failed to build:

rustc

❗ ❗ ❗ ❗ ❗

Instruction count

This is the most reliable metric that we have; it was used to determine the overall result at the top of this comment. However, even this metric can sometimes exhibit noise.

	mean	range	count
Regressions ❌ (primary)	0.3%	[0.2%, 0.4%]	12
Regressions ❌ (secondary)	0.4%	[0.3%, 0.5%]	9
Improvements ✅ (primary)	-0.8%	[-1.4%, -0.4%]	109
Improvements ✅ (secondary)	-0.9%	[-1.6%, -0.3%]	32
All ❌✅ (primary)	-0.7%	[-1.4%, 0.4%]	121

Max RSS (memory usage)

Results (primary 1.8%, secondary -0.1%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	1.8%	[1.1%, 3.1%]	37
Regressions ❌ (secondary)	4.1%	[2.4%, 9.9%]	6
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.2%	[-4.9%, -1.8%]	8
All ❌✅ (primary)	1.8%	[1.1%, 3.1%]	37

Cycles

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

Binary size

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

Bootstrap: missing data
Artifact size: 365.51 MiB -> 365.49 MiB (-0.01%)

Kobzol · 2025-04-14T07:14:42Z

The bootstrap error looks spurious.

Kobzol · 2025-04-14T07:14:50Z

@bors try @rust-timer queue

bors · 2025-04-14T07:16:00Z

⌛ Trying commit 3269f5a with merge 07e2c12...

Allow out of order dep graph node encoding This allows out of order dep graph node encoding by also encoding the index instead of using the file node order as the index. `MemEncoder` is also brought back to life and used for encoding. Both of these are done to enable thread-local encoding of dep graph nodes. This is based on rust-lang#139636.

bors · 2025-04-14T09:22:31Z

☀️ Try build successful - checks-actions
Build commit: 07e2c12 (07e2c121709ab80ce224c9a471997212c3e9a98d)

rust-timer · 2025-04-14T10:38:34Z

Finished benchmarking commit (07e2c12): comparison URL.

Overall result: ❌✅ regressions and improvements - please read the text below

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

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

Instruction count

This is the most reliable metric that we have; it was used to determine the overall result at the top of this comment. However, even this metric can sometimes exhibit noise.

	mean	range	count
Regressions ❌ (primary)	0.3%	[0.2%, 0.5%]	14
Regressions ❌ (secondary)	0.5%	[0.3%, 1.3%]	11
Improvements ✅ (primary)	-0.7%	[-1.3%, -0.4%]	108
Improvements ✅ (secondary)	-0.9%	[-1.5%, -0.6%]	23
All ❌✅ (primary)	-0.6%	[-1.3%, 0.5%]	122

Max RSS (memory usage)

Results (primary 1.7%, secondary -0.2%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	1.7%	[1.2%, 2.6%]	39
Regressions ❌ (secondary)	3.8%	[1.8%, 9.8%]	5
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.0%	[-4.9%, -1.7%]	7
All ❌✅ (primary)	1.7%	[1.2%, 2.6%]	39

Cycles

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

Binary size

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

Bootstrap: 779.942s -> 780.359s (0.05%)
Artifact size: 365.12 MiB -> 365.08 MiB (-0.01%)

oli-obk · 2025-04-16T09:42:01Z

@bors r+

bors · 2025-04-16T09:42:03Z

📌 Commit 8fc610e has been approved by oli-obk

It is now in the queue for this repository.

Allow out of order dep graph node encoding This allows out of order dep graph node encoding by also encoding the index instead of using the file node order as the index. `MemEncoder` is also brought back to life and used for encoding. Both of these are done to enable thread-local encoding of dep graph nodes. This is based on rust-lang#139636.

bors · 2025-04-16T11:43:54Z

⌛ Testing commit 8fc610e with merge 2714e13...

bors · 2025-04-16T13:41:30Z

💔 Test failed - checks-actions

compiler/rustc_query_system/src/dep_graph/serialized.rs

compiler/rustc_serialize/src/opaque/mem_encoder.rs

Zoxc · 2025-04-24T09:07:17Z

@rustbot ready

compiler/rustc_serialize/src/opaque/mem_encoder.rs

oli-obk · 2025-04-24T09:42:34Z

compiler/rustc_serialize/src/opaque/mem_encoder.rs

-    pub fn write_with<const N: usize>(&mut self, visitor: impl FnOnce(&mut [u8; N]) -> usize) {
+    pub fn write_with<const N: usize>(
+        &mut self,
+        visitor: impl FnOnce(&mut [MaybeUninit<u8>; N]) -> usize,
+    ) {
        self.data.reserve(N);


I still think we should just not do this commit and instead use resize here on the Vec and use last_chunk to safely take out the array. I do not think this will have a performance impact in practice and it avoids the added maybeuninit complexity and the unsafe code

rustbot assigned davidtwco Apr 13, 2025

Zoxc force-pushed the out-of-order-dep-graph branch from 4365461 to c31c18a Compare April 13, 2025 17:54

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Zoxc force-pushed the out-of-order-dep-graph branch from c31c18a to 3269f5a Compare April 13, 2025 18:33

Zoxc mentioned this pull request Apr 13, 2025

Use thread local dep graph encoding #139758

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bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Apr 16, 2025

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cjgillot reviewed Apr 18, 2025

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Zoxc force-pushed the out-of-order-dep-graph branch 2 times, most recently from 6c0e3f0 to fa5c5e0 Compare April 22, 2025 02:25

oli-obk requested changes Apr 22, 2025

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Zoxc added 4 commits April 22, 2025 16:57

Add index to the dep graph format and encode via MemEncoder

c6735f9

Use IndexVec::from_elem_n

4ec74df

Tweak edges

36fa327

Make sure there's no duplicate indices in the dep graph

9a6e8b3

Zoxc force-pushed the out-of-order-dep-graph branch from 381b5b4 to 68513cb Compare April 22, 2025 14:57

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Apr 24, 2025

oli-obk requested changes Apr 24, 2025

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rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Apr 24, 2025

Zero the buffer passed from write_with

c8e7c62

Zoxc force-pushed the out-of-order-dep-graph branch from 68513cb to c8e7c62 Compare April 25, 2025 06:56

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Allow out of order dep graph node encoding #139756

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Overall result: ❌✅ regressions and improvements - BENCHMARK(S) FAILED

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Overall result: ❌✅ regressions and improvements - please read the text below

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