Optimize TLS on Windows#102655

joboet · 2022-10-04T13:03:26Z

This implements the suggestion in the current TLS code to embed the linked list of destructors in the StaticKey structure to save allocations. Additionally, locking is avoided when no destructor needs to be run. By using one Windows-provided Once per key instead of a global lock, locking is more finely-grained (this unblocks #100579).

rust-highfive · 2022-10-04T13:03:30Z

r? @ChrisDenton

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rustbot · 2022-10-04T13:03:30Z

Hey! It looks like you've submitted a new PR for the library teams!

If this PR contains changes to any rust-lang/rust public library APIs then please comment with @rustbot label +T-libs-api -T-libs to tag it appropriately. If this PR contains changes to any unstable APIs please edit the PR description to add a link to the relevant API Change Proposal or create one if you haven't already. If you're unsure where your change falls no worries, just leave it as is and the reviewer will take a look and make a decision to forward on if necessary.

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library/std/src/sys/windows/thread_local_key.rs

ChrisDenton

This approach seems reasonable to me. I just have a few tiny nits but nothing major.

library/std/src/sys/windows/thread_local_key.rs

joboet · 2022-10-07T10:41:49Z

@ChrisDenton Should I clean up the CI changes now? They obviously cannot be merged.

ChrisDenton · 2022-10-08T07:45:36Z

Yes please. Could you also squish the commits?

Speaking of, I notice you've moved some functions around (run_dtors has been moved up and get/set have switched places). I don't mind that but could you put any moves into a commit separate from the changes so that history/diff tools can understand what happened.

joboet · 2022-10-08T18:23:23Z

Yes please. Could you also squish the commits?

Speaking of, I notice you've moved some functions around (run_dtors has been moved up and get/set have switched places). I don't mind that but could you put any moves into a commit separate from the changes so that history/diff tools can understand what happened.

Done 🎉

ChrisDenton · 2022-10-10T12:22:09Z

@bors r+

bors · 2022-10-10T12:22:11Z

📌 Commit d457801 has been approved by ChrisDenton

It is now in the queue for this repository.

Optimize TLS on Windows This implements the suggestion in the current TLS code to embed the linked list of destructors in the `StaticKey` structure to save allocations. Additionally, locking is avoided when no destructor needs to be run. By using one Windows-provided `Once` per key instead of a global lock, locking is more finely-grained (this unblocks rust-lang#100579).

bors · 2022-10-13T06:49:32Z

⌛ Testing commit d457801 with merge fa0ca78...

bors · 2022-10-13T10:43:55Z

☀️ Test successful - checks-actions
Approved by: ChrisDenton
Pushing fa0ca78 to master...

rust-timer · 2022-10-13T12:04:17Z

Finished benchmarking commit (fa0ca78): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

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

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.

	mean¹	range	count²
Regressions ❌ (primary)	0.9%	[0.9%, 0.9%]	1
Regressions ❌ (secondary)	4.5%	[2.1%, 8.2%]	3
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.9%	[0.9%, 0.9%]	1

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.

	mean¹	range	count²
Regressions ❌ (primary)	3.1%	[2.1%, 4.2%]	3
Regressions ❌ (secondary)	3.0%	[3.0%, 3.0%]	1
Improvements ✅ (primary)	-2.6%	[-2.7%, -2.6%]	2
Improvements ✅ (secondary)	-2.6%	[-3.2%, -1.9%]	3
All ❌✅ (primary)	0.8%	[-2.7%, 4.2%]	5

the arithmetic mean of the percent change ↩ ↩²
number of relevant changes ↩ ↩²

…sDenton Avoid dropping TLS Key on sgx rust-lang#102655 reenabled dropping thread local `Key` on every platform ([library/std/src/sys_common/thread_local_key.rs](rust-lang-ci@fa0ca78#diff-5cb9acf9e243f35c975fa9fbac4885519dc104626bc03610dfa7a20bc79641ceL237-R215)). That's causing problems at least for sgx. cc: `@jethrogb` `@ChrisDenton`

fix weak memory bug in TLS on Windows We need to store the `key` *after* we register the dtor. Now I hope there isn't also some other reason why we have to actually register the dtor last... `@joboet` is there a reason you picked this particular order in rust-lang#102655? Fixes rust-lang#123583

Rollup merge of rust-lang#124281 - RalfJung:win-tls, r=joboet fix weak memory bug in TLS on Windows We need to store the `key` *after* we register the dtor. Now I hope there isn't also some other reason why we have to actually register the dtor last... `@joboet` is there a reason you picked this particular order in rust-lang#102655? Fixes rust-lang#123583

fix weak memory bug in TLS on Windows We need to store the `key` *after* we register the dtor. Now I hope there isn't also some other reason why we have to actually register the dtor last... `@joboet` is there a reason you picked this particular order in rust-lang/rust#102655? Fixes rust-lang/rust#123583

rust-highfive assigned ChrisDenton Oct 4, 2022

rustbot added T-infra Relevant to the infrastructure team, which will review and decide on the PR/issue. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Oct 4, 2022

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Oct 4, 2022

luqmana reviewed Oct 4, 2022

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ChrisDenton reviewed Oct 5, 2022

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std: optimize TLS on Windows

d457801

joboet force-pushed the windows_tls_opt branch from 6244ee9 to d457801 Compare October 8, 2022 18:19

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 Oct 10, 2022

matthiaskrgr mentioned this pull request Oct 11, 2022

Rollup of 8 pull requests #102930

Closed

bors added the merged-by-bors This PR was explicitly merged by bors. label Oct 13, 2022

bors merged commit fa0ca78 into rust-lang:master Oct 13, 2022

rustbot added this to the 1.66.0 milestone Oct 13, 2022

bors mentioned this pull request Oct 13, 2022

Cleanup TLS implementation #102656

Closed

joboet deleted the windows_tls_opt branch October 13, 2022 10:46

joboet mentioned this pull request Oct 13, 2022

std: use sync::Mutex for internal statics #100579

Merged

raoulstrackx mentioned this pull request Oct 13, 2022

Avoid dropping TLS Key on sgx #103017

Merged

RalfJung mentioned this pull request Oct 14, 2022

can't call foreign function: InitOnceBeginInitialize when running on Windows rust-lang/miri#2595

Closed

RalfJung mentioned this pull request Apr 23, 2024

fix weak memory bug in TLS on Windows #124281

Merged

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bors commented Oct 13, 2022

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rust-timer commented Oct 13, 2022

Overall result: no relevant changes - no action needed

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