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Did you try Mold? (lemmy.ml)

submitted 1 year ago by [email protected] to c/[email protected]

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According to the readme, Rust is supported, did anyone tried and noticed improvement? rui314/mold: Mold: A Modern Linker 🦠 https://github.com/rui314/mold

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[–] [email protected] 2 points 1 year ago* (last edited 1 year ago)

Okay. I updated mold to v2.0.0. Added "-Z", "time-passes" to get link times, ran cargo with --timings to get CPU utilization graphs. Tested on two projects of mine (the one from yesterday is "X").

Link times are picked as the best from 3-4 runs, changing only white space on main.rs.

`lto="fat"`	lld	mold
project X (cu=1)	105.923	106.380

Project X (cu=8)	103.512	103.513

Project S (cu=1)	94.290	94.969

Project S (cu=8)	100.118	100.449

Observations (lto="fat"): As expected, not a lot of utilization of multi-core. Using codegen-units larger than 1 may even cause a regression in link time. Choice of linker between lld and mold appears to be of no significance.

`lto="thin"`	lld	mold
project X (cu=1)	46.596	47.118

Project X (cu=8)	34.167	33.839

Project X (cu=16)	36.296	36.621

Project S (cu=1)	41.817	41.404

Project S (cu=8)	32.062	32.162

Project S (cu=16)	35.780	36.074

Observations (lto="thin"): Here, we see parallel LLVM_lto_optimize runs kicking in. Testing with codegen-units=16 was also done. In that case, the number of parallel LLVM_lto_optimize runs was so big, the synchronization overhead caused a regression running that test on a humble workstation powered by an Intel i7-7700K processor (4 physical, 8 logical cores only). The results will probably look different running this test case (cu=16) in a more powerful setup. But still, the choice of linker between lld and mold appears to be of no significance.

`lto=false`	lld	mold
project X (cu=1)	29.160	29.231

Project X (cu=8)	8.130	8.293

Project X (cu=16)	7.076	6.953

Project S (cu=1)	11.996	12.069

Project S (cu=8)	4.418	4.462

Project S (cu=16)	4.357	4.455

Observations (lto=false): Here, codegen-units becomes the dominant factor with no heavy LLVM_lto_optimize runs involved. Going above codegen-units=8 does not hurt link time. Still, the choice of linker between lld and mold appears to be of no significance.

`lto="off"`	lld	mold
project X (cu=1)	29.109	29.201
Project X (cu=8)	5.896	6.117
Project X (cu=16)	3.479	3.637
Project S (cu=1)	11.732	11.742
Project S (cu=8)	2.354	2.355
Project S (cu=16)	1.517	1.499

Observations (lto="off"): Same observations as lto=false. Still, the choice of linker between lld and mold appears to be of no significance.

Debug builds link in <.4 seconds.