Date: Mon, 31 Dec 2018 23:32:09 -0800 From: Brian Neal <brian@aceshardware.com> To: Garance A Drosehn <drosih@rpi.edu> Cc: freebsd-hackers@freebsd.org Subject: Re: Speculative: Rust for base system components Message-ID: <92bd5362-d898-aa12-8f3d-9fbe23f38e0c@aceshardware.com> In-Reply-To: <72922F2C-9D27-47AA-BB1C-2DA8589CF008@rpi.edu> References: <ca76e5f7-6e59-bd67-144a-90ad66f0252e@metricspace.net> <7d7bc47d-04cf-2f9b-00a3-e3d9d92b3623@aceshardware.com> <72922F2C-9D27-47AA-BB1C-2DA8589CF008@rpi.edu>
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It was a debug build with no optimization for either compiler. But we can easily run a variety of settings for comparison: Compiler Flags Inst. Count Build Time ====================================================================== clang 7.0.0 none 33 296ms -O3 23 341ms rustc 1.31.0 none 110 606ms -C opt-level=3 67 643ms gcc 8.2 none 37 211ms -O2 24 249ms -O3 119* 206ms * With -O3, gcc unrolled and vectorized the loop. The other compilers did not emit vectorized code at any of the standard optimization levels. So, essentially, double the build time and ~3 times the code for the same logic. On 12/31/2018 7:23 PM, Garance A Drosehn wrote: > > On 31 Dec 2018, at 23:04, Brian Neal wrote: > > This is a good read on some of the pitfalls of Rust: > > https://hackernoon.com/why-im-dropping-rust-fd1c32986c88 > > In terms of performance, take a look at Rust on godbolt...a quick > test I just ran with a trivial program that sums up a sequence of > odd numbers is 29 instructions in C on clang 7.0 and a whopping > 137 (!!!) on rustc 1.31.0! > > Crazy... > > Did you compile your program as a "release build", or just as a > standard (quick) build? > > -- > Garance Alistair Drosehn = drosih@rpi.edu > Senior Systems Programmer or gad@FreeBSD.org > Rensselaer Polytechnic Institute; Troy, NY; USA >
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