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Up to 8% RSS regression because of #44142 #44576

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arielb1 opened this issue Sep 14, 2017 · 6 comments
Closed

Up to 8% RSS regression because of #44142 #44576

arielb1 opened this issue Sep 14, 2017 · 6 comments
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regression-from-stable-to-nightly Performance or correctness regression from stable to nightly. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.

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@arielb1 arielb1 added regression-from-stable-to-nightly Performance or correctness regression from stable to nightly. I-nominated T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Sep 14, 2017
@alexcrichton
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alexcrichton commented Sep 15, 2017

A more focused graph

@alexcrichton
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Interestingly if you widen the view a bit you'll see:

May be worth looking into #44275 as well?

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Specifically before/after #44142, massif snapshots -- I've only included the peak snapshot in the output there.

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alexcrichton commented Sep 15, 2017

Looks like basically all of the memory is here, aka we have a bigger dep graph. Turns out adding more queries makes a bigger dep graph :)

alexcrichton added a commit to alexcrichton/rust that referenced this issue Sep 15, 2017
This commit alters the `query` function in the dep graph module to preallocate
memory using `with_capacity` instead of relying on automatic growth. Discovered
in rust-lang#44576 it was found that for the syntex_syntax clean incremental benchmark
the peak memory usage was found when the dep graph was being saved, particularly
the `DepGraphQuery` data structure itself. PRs like rust-lang#44142 which add more
queries end up just making this much larger!

I didn't see an immediately obvious way to reduce the size of the
`DepGraphQuery` object, but it turns out that `with_capacity` helps quite a bit!
Locally 831 MB was used [before] this commit, and 770 MB is in use at the peak
of the compiler [after] this commit. That's a nice 7.5% improvement! This won't
quite make up for the losses in rust-lang#44142 but I figured it's a good start.

[before]: https://gist.github.com/alexcrichton/2d2b9c7a65503761925c5a0bcfeb0d1e
[before]: https://gist.github.com/alexcrichton/6da51f2a6184bfb81694cc44f06deb5b
@alexcrichton
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I cashed in some easy savings in #44586, but it doesn't actually fix the "regression", but we likely shouldn't call it a regression as it also fixed a number of would-be bugs!

GuillaumeGomez added a commit to GuillaumeGomez/rust that referenced this issue Sep 15, 2017
…elwoerister

rustc: Preallocate when building the dep graph

This commit alters the `query` function in the dep graph module to preallocate
memory using `with_capacity` instead of relying on automatic growth. Discovered
in rust-lang#44576 it was found that for the syntex_syntax clean incremental benchmark
the peak memory usage was found when the dep graph was being saved, particularly
the `DepGraphQuery` data structure itself. PRs like rust-lang#44142 which add more
queries end up just making this much larger!

I didn't see an immediately obvious way to reduce the size of the
`DepGraphQuery` object, but it turns out that `with_capacity` helps quite a bit!
Locally 831 MB was used [before] this commit, and 770 MB is in use at the peak
of the compiler [after] this commit. That's a nice 7.5% improvement! This won't
quite make up for the losses in rust-lang#44142 but I figured it's a good start.

[before]: https://gist.github.com/alexcrichton/2d2b9c7a65503761925c5a0bcfeb0d1e
[before]: https://gist.github.com/alexcrichton/6da51f2a6184bfb81694cc44f06deb5b
alexcrichton added a commit to alexcrichton/rust that referenced this issue Sep 16, 2017
…elwoerister

rustc: Preallocate when building the dep graph

This commit alters the `query` function in the dep graph module to preallocate
memory using `with_capacity` instead of relying on automatic growth. Discovered
in rust-lang#44576 it was found that for the syntex_syntax clean incremental benchmark
the peak memory usage was found when the dep graph was being saved, particularly
the `DepGraphQuery` data structure itself. PRs like rust-lang#44142 which add more
queries end up just making this much larger!

I didn't see an immediately obvious way to reduce the size of the
`DepGraphQuery` object, but it turns out that `with_capacity` helps quite a bit!
Locally 831 MB was used [before] this commit, and 770 MB is in use at the peak
of the compiler [after] this commit. That's a nice 7.5% improvement! This won't
quite make up for the losses in rust-lang#44142 but I figured it's a good start.

[before]: https://gist.github.com/alexcrichton/2d2b9c7a65503761925c5a0bcfeb0d1e
[before]: https://gist.github.com/alexcrichton/6da51f2a6184bfb81694cc44f06deb5b
frewsxcv added a commit to frewsxcv/rust that referenced this issue Sep 16, 2017
…elwoerister

rustc: Preallocate when building the dep graph

This commit alters the `query` function in the dep graph module to preallocate
memory using `with_capacity` instead of relying on automatic growth. Discovered
in rust-lang#44576 it was found that for the syntex_syntax clean incremental benchmark
the peak memory usage was found when the dep graph was being saved, particularly
the `DepGraphQuery` data structure itself. PRs like rust-lang#44142 which add more
queries end up just making this much larger!

I didn't see an immediately obvious way to reduce the size of the
`DepGraphQuery` object, but it turns out that `with_capacity` helps quite a bit!
Locally 831 MB was used [before] this commit, and 770 MB is in use at the peak
of the compiler [after] this commit. That's a nice 7.5% improvement! This won't
quite make up for the losses in rust-lang#44142 but I figured it's a good start.

[before]: https://gist.github.com/alexcrichton/2d2b9c7a65503761925c5a0bcfeb0d1e
[before]: https://gist.github.com/alexcrichton/6da51f2a6184bfb81694cc44f06deb5b
alexcrichton added a commit to alexcrichton/rust that referenced this issue Sep 17, 2017
…elwoerister

rustc: Preallocate when building the dep graph

This commit alters the `query` function in the dep graph module to preallocate
memory using `with_capacity` instead of relying on automatic growth. Discovered
in rust-lang#44576 it was found that for the syntex_syntax clean incremental benchmark
the peak memory usage was found when the dep graph was being saved, particularly
the `DepGraphQuery` data structure itself. PRs like rust-lang#44142 which add more
queries end up just making this much larger!

I didn't see an immediately obvious way to reduce the size of the
`DepGraphQuery` object, but it turns out that `with_capacity` helps quite a bit!
Locally 831 MB was used [before] this commit, and 770 MB is in use at the peak
of the compiler [after] this commit. That's a nice 7.5% improvement! This won't
quite make up for the losses in rust-lang#44142 but I figured it's a good start.

[before]: https://gist.github.com/alexcrichton/2d2b9c7a65503761925c5a0bcfeb0d1e
[before]: https://gist.github.com/alexcrichton/6da51f2a6184bfb81694cc44f06deb5b
@alexcrichton
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Looks like we've recovered the losses and this particular peak may also go away soon, so closing.

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