Std library inclusion policy, and a data point of compilation times

leonardo · 2017-06-22T08:50:38.826Z

nightly-x86_64-pc-windows-gnu - V.1.20.0-nightly (622e7e648 2017-06-21):

rustc -C opt-level=0 --emit=metadata test.rs: 0.18 seconds
rustc -C opt-level=0 -C prefer-dynamic test.rs: 0.90 seconds, 212_677 bytes
rustc -C opt-level=3 -C target-cpu=native test.rs: 1.60 seconds, 1_097_570 bytes
rustc test.rs: 0.94 seconds, 1_230_592 bytes
rustc -O test.rs: 1.56 seconds, 1_096_118 bytes

In other code I’m seeing 8% increase of run-time, and up to about 20% increase of compile-times.

leonardo · 2017-06-27T17:37:30.657Z

I’ve filed a bug report with a small self-contained test program:

github.com/rust-lang/rust

Issue: Slower binaries since some days

opened by leonardo-m on 2017-06-27

closed by alexcrichton on 2017-08-12

This could have the same causes of Issue 42808 (i.e. regression due to #42313), or perhaps not.
This small test program solves...

C-enhancement I-slow P-medium regression-from-stable-to-beta T-compiler

leonardo · 2017-08-30T11:17:28.788Z

leonardo:

rustc -C opt-level=0 --emit=metadata test.rs: 0.18 seconds
rustc -C opt-level=0 -C prefer-dynamic test.rs: 0.90 seconds, 212_677 bytes
rustc -C opt-level=3 -C target-cpu=native test.rs: 1.60 seconds, 1_097_570 bytes
rustc test.rs: 0.94 seconds, 1_230_592 bytes
rustc -O test.rs: 1.56 seconds, 1_096_118 bytes

With the last Nightly the compiler is a little slower, the binaries are a little slower (but one important binary of mine was almost 20% slower) but the biggest difference is in the binary sizes, grown about 220-250%:

nightly-x86_64-pc-windows-gnu 1.21.0-nightly (c11f689d2 2017-08-29):

rustc -C opt-level=0 --emit=metadata test.rs: 0.18 seconds
rustc -C opt-level=0 -C prefer-dynamic test.rs: 0.97 seconds, 291_973 bytes
rustc -C opt-level=3 -C target-cpu=native test.rs: 1.66 seconds, 2_744_288 bytes
rustc test.rs: 1.07 seconds, 2_881_133 bytes
rustc -O test.rs: 1.65 seconds, 2_743_776 bytes

matklad · 2017-08-30T11:31:20.693Z

leonardo:

but the biggest difference is in the binary sizes, grown about 220-250%:

Looks like a bug to me! Have you opened an issue?

leonardo · 2017-08-30T11:36:09.376Z

Not yet. Currently discussing the problem on IRC…

Update: apparently the problem is not visible in the msvc and Linux64 targets. I’ve seen it on the gnu64 target. Is someone willing and able to test it on the gnu32 target?

https://github.com/rust-lang/rust/issues/44183

leonardo · 2017-12-18T20:20:26.711Z

In my code since the 1.24.0-nightly 2017-12-15 I’m seeing about 20-22% increase of compilation times using --emit=metadata (and I am using less than 30 constants), and more than 5% performance decrease of the binary. And every day since (2017-12-16 and 2017-12-17) things are getting a little worse. Alarm!

emoon · 2017-12-19T12:06:23.905Z

Ouch! That sounds pretty bad. Should post on this on the internals list perhaps?

leonardo · 2017-12-19T12:13:59.716Z

First I’ll try to better pinpoint where the problems are…

emoon · 2017-12-19T12:14:41.403Z

Sounds good

leonardo · 2017-12-20T23:03:11.417Z

I’ve opened a bug report, the whole deal took me more time than expected:

github.com/rust-lang/rust

Issue: Slower binary, slower compiler, bigger binary since some days

opened by leonardo-m on 2017-12-20

In the 2017-12-14 Nightly I've seen a significant (almost 20%) compilation-time increase when I use --emit=metadata on my code. And the...

leonardo · 2017-12-21T09:01:26.877Z

In the bug report comments arielb1i is asking if someone is able & willing to reproduce the problem on other hosts.

juleskers · 2017-12-29T15:05:00.055Z

(quick compliment: I admire your continued efforts to measure, detect, and pin-point these compiler slowdowns. It is non-trivial and valuable feedback. Thanks! )

leonardo · 2018-01-27T10:41:17.384Z

The last Nightly (1.25.0 bacb5c58d 2018-01-26 x86_64-pc-windows-gnu) gives me 20% smaller stripped binaries, it’s a significant improvement. The binaries are a bit slower, but not significantly so.

leonardo · 2018-03-03T06:55:53.051Z

With the last Nightly (x86_64-pc-windows-gnu 9cb18a92a 2018-03-02) the compilation using --emit=metadata is twice slower.

leonardo · 2018-03-04T11:07:04.201Z

And it was mostly fixed in the successive Nightly.

scottmcm · 2018-03-04T11:22:11.837Z

Probably this, which was fixed by reverting a bit that wasn’t meant to be included

github.com/rust-lang/rust

Issue: Performance regression between 3/1 and 3/2

opened by ishitatsuyuki on 2018-03-02

closed by bors on 2018-03-03

Per #47861 (comment).

C-bug I-compiletime T-compiler regression-from-stable-to-nightly

leonardo · 2018-03-15T09:07:53.336Z

leonardo:

rustc -C opt-level=0 --emit=metadata test.rs: 0.18 seconds
rustc -C opt-level=0 -C prefer-dynamic test.rs: 0.97 seconds, 291_973 bytes
rustc -C opt-level=3 -C target-cpu=native test.rs: 1.66 seconds, 2_744_288 bytes
rustc test.rs: 1.07 seconds, 2_881_133 bytes
rustc -O test.rs: 1.65 seconds, 2_743_776 bytes

The last nightly compiles again (rustc x86_64-pc-windows-gnu 1.26.0-nightly, 521d91c6b 2018-03-14):

rustc -C opt-level=0 --emit=metadata test.rs: 0.22 seconds
rustc -C opt-level=0 -C prefer-dynamic test.rs: 1.92 seconds, 136_704 stripped bytes
rustc test.rs: 2.00 seconds, 805_888 stripped bytes
rustc -O test.rs: 2.34 seconds, 733_184 stripped bytes
rustc -C opt-level=3 -C target-cpu=native test.rs: 2.35 seconds, 735_232 stripped bytes
rustc -C opt-level=3 -C target-cpu=native -C panic=abort -Z mir-opt-level=3 -C lto test.rs: 4.10 seconds, 202_240 stripped bytes

But now the compiler is much slower (perhaps nearly un-usably slower for me). In other longer code of mine I am seeing 11X compilation times using “–emit=metadata”, and 15X compilation times for optimized builds

michaelwoerister · 2018-03-15T11:27:56.225Z

@leonardo, that nightly is the first after the merge of the MIRI-based constant evaluator which caused some performance regressions. We are actively working on getting performance back to where it was. On a grand scale, we th regression has not been as severe as you are observing (see http://perf.rust-lang.org/). Would you mind providing a link to the programs you are testing?

leonardo · 2018-03-18T15:51:32.485Z

And now it’s fixed, I am seeing (Nightly x86_64-pc-windows-gnu adf2135ad 2018-03-17) about 6% slowdown in the optimized compilation.

leonardo · 2018-05-20T13:18:36.707Z

The compiler performance has changed:

rustc 1.28.0-nightly (a3085756e 2018-05-19) x86_64-pc-windows-gnu:

rustc -C opt-level=0 --emit=metadata test.rs: 0.23 seconds
rustc -C opt-level=0 -C prefer-dynamic test.rs: 0.49 seconds, 118_272 stripped bytes
rustc test.rs: 0.83 seconds, 818_688 stripped bytes
rustc -O test.rs: 1.08 seconds, 739_328 stripped bytes
rustc -C opt-level=3 -C target-cpu=native test.rs: 1.02 seconds, 739_840 stripped bytes
rustc -C opt-level=3 -C target-cpu=native -C panic=abort -Z mir-opt-level=3 -C lto test.rs: Issue #50411

The performance problems with “–emit=metadata” I saw months ago seems mostly solved now, perhaps thanks to https://github.com/rust-lang/rust/pull/50744 too.