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Remove sharding for VecCache #123556

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Merged
merged 1 commit into from
Apr 7, 2024
Merged

Remove sharding for VecCache #123556

merged 1 commit into from
Apr 7, 2024

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Mark-Simulacrum
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This sharding is never used (per the comment in code). If we re-add sharding at some point in the future this is cheap to restore, but for now no need for the extra complexity.

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Remove sharding for VecCache
668b318 
This sharding is never used (per the comment in code). If we re-add
sharding at some point in the future this is cheap to restore, but for
now no need for the extra complexity.
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rustbot commented Apr 6, 2024

r? @Nadrieril

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@rustbot rustbot added A-query-system Area: The rustc query system (https://rustc-dev-guide.rust-lang.org/query.html) S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Apr 6, 2024
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@bors try @rust-timer queue

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@rustbot rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Apr 6, 2024
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bors commented Apr 6, 2024

⌛ Trying commit 668b318 with merge 2266f0b...

bors added a commit to rust-lang-ci/rust that referenced this pull request Apr 6, 2024
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Auto merge of rust-lang#123556 - Mark-Simulacrum:drop-unused-sharding…
2266f0b 
…, r=<try>

Remove sharding for VecCache

This sharding is never used (per the comment in code). If we re-add sharding at some point in the future this is cheap to restore, but for now no need for the extra complexity.
Nadrieril
Nadrieril reviewed Apr 6, 2024
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compiler/rustc_query_system/src/query/caches.rs
Comment on lines -125 to 124
let lock = self.cache.lock_shard_by_hash(key.index() as u64);
let lock = self.cache.lock();
if let Some(Some(value)) = lock.get(*key) { Some(*value) } else { None }
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IndexVec is contiguous, right? Did the old implementation make much sense? From a quick glance, it seems to me that if the indices were in fact high enough to shard we'd end up with largely empty IndexVecs in each shard

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Yes, that sounds plausible. In any case IIRC the sharding uses the high bits and we'd almost certainly run out of memory first.

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bors commented Apr 6, 2024

☀️ Try build successful - checks-actions
Build commit: 2266f0b (2266f0b25da94ef800559d741b4aad9e7cdfc889)

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Finished benchmarking commit (2266f0b): comparison URL.

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

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 a highly reliable metric that was used to determine the overall result at the top of this comment.

mean range count
Regressions ❌
(primary)		 - - 0
Regressions ❌
(secondary)		 0.5% [0.4%, 1.0%] 7
Improvements ✅
(primary)		 - - 0
Improvements ✅
(secondary)		 -0.9% [-1.0%, -0.7%] 4
All ❌✅ (primary) - - 0

Max RSS (memory usage)

Results

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)		 0.7% [0.7%, 0.7%] 1
Regressions ❌
(secondary)		 - - 0
Improvements ✅
(primary)		 -5.1% [-5.1%, -5.1%] 1
Improvements ✅
(secondary)		 - - 0
All ❌✅ (primary) -2.2% [-5.1%, 0.7%] 2

Cycles

Results

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)		 - - 0
Regressions ❌
(secondary)		 - - 0
Improvements ✅
(primary)		 - - 0
Improvements ✅
(secondary)		 -2.2% [-2.2%, -2.2%] 1
All ❌✅ (primary) - - 0

Binary size

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

Bootstrap: 666.761s -> 667.971s (0.18%)
Artifact size: 318.27 MiB -> 318.14 MiB (-0.04%)

@rustbot rustbot added perf-regression Performance regression. and removed S-waiting-on-perf Status: Waiting on a perf run to be completed. labels Apr 6, 2024
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Looks good!

@bors r+

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bors commented Apr 6, 2024

📌 Commit 668b318 has been approved by Nadrieril

It is now in the queue for this repository.

@bors 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 6, 2024
@Mark-Simulacrum Mark-Simulacrum added the perf-regression-triaged The performance regression has been triaged. label Apr 6, 2024
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bors commented Apr 7, 2024

⌛ Testing commit 668b318 with merge af25253...

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bors commented Apr 7, 2024

☀️ Test successful - checks-actions
Approved by: Nadrieril
Pushing af25253 to master...

@bors bors added the merged-by-bors This PR was explicitly merged by bors. label Apr 7, 2024
@bors bors merged commit af25253 into rust-lang:master Apr 7, 2024
12 checks passed
@rustbot rustbot added this to the 1.79.0 milestone Apr 7, 2024
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Finished benchmarking commit (af25253): comparison URL.

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

Next Steps: If you can justify the regressions found in this perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please open an issue or create a new PR that fixes the regressions, add a comment linking to the newly created issue or PR, and then add the perf-regression-triaged label to this PR.

@rustbot label: +perf-regression
cc @rust-lang/wg-compiler-performance

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

mean range count
Regressions ❌
(primary)		 0.4% [0.4%, 0.4%] 1
Regressions ❌
(secondary)		 0.5% [0.2%, 1.0%] 5
Improvements ✅
(primary)		 - - 0
Improvements ✅
(secondary)		 -0.9% [-1.1%, -0.7%] 4
All ❌✅ (primary) 0.4% [0.4%, 0.4%] 1

Max RSS (memory usage)

Results

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)		 - - 0
Regressions ❌
(secondary)		 - - 0
Improvements ✅
(primary)		 -4.7% [-5.7%, -3.7%] 2
Improvements ✅
(secondary)		 - - 0
All ❌✅ (primary) -4.7% [-5.7%, -3.7%] 2

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: 668.846s -> 668.633s (-0.03%)
Artifact size: 318.48 MiB -> 318.20 MiB (-0.09%)

@Mark-Simulacrum Mark-Simulacrum deleted the drop-unused-sharding branch April 11, 2024 15:01
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A-query-system Area: The rustc query system (https://rustc-dev-guide.rust-lang.org/query.html) merged-by-bors This PR was explicitly merged by bors. perf-regression Performance regression. perf-regression-triaged The performance regression has been triaged. S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.
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