[ruby-core:118575] [Ruby master Bug#20604] Performance regression in C++ extensions due to lack of optimization flags by default since Ruby 2.7
From:
"alanwu (Alan Wu) via ruby-core" <ruby-core@...>
Date:
2024-07-12 00:15:59 UTC
List:
ruby-core #118575
Issue #20604 has been updated by alanwu (Alan Wu). > Please specify $CXXFLAGS individually. Just some additional information about how to do this. If you maintain a gem, you can add the desired flags to $CXXFLAGS in your `extconf.rb`. As an user, you can install a gem while adding to $CXXFLAGS using `--with-cxxflags` without changing the gem. This is an `mkmf` feature. For example: ``` $ gem install sassc -- --with-cxxflags=-O3 ``` ---------------------------------------- Bug #20604: Performance regression in C++ extensions due to lack of optimization flags by default since Ruby 2.7 https://bugs.ruby-lang.org/issues/20604#change-109100 * Author: ntkme (Natsuki Natsume) * Status: Rejected * ruby -v: ruby 3.3.3 (2024-06-12 revision f1c7b6f435) [arm64-darwin23] * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- I found a significant performance regression in `sassc` gem when comparing Ruby 2.6 and later, that the extension is running more than 10x slower. I have tracked it down to this commit: https://github.com/ruby/ruby/commit/733aa2f8b578d03bbcb91d2f496b01e3b990c7e8 This commit removed all default CXXFLAGS from RbConfig that were previously set, including `$optflags`, which has `-O3`. Many of the C++ extensions like sassc use extconf/mkmf to compile, and they have assumed optflags are already set for CXXFLAGS. Without `-O3` as part of the default, the extensions are compiled without any optimizations and thus become extremely slow. It is difficult for a regular user to find out the reason of the slowness, nor to say figuring out how to override CXXFLAGS for a native extension. I'm not sure what was the reason of the change, but I think we should at least set `$optflags` in CXXFLAGS by default. -- https://bugs.ruby-lang.org/ ______________________________________________ ruby-core mailing list -- [email protected] To unsubscribe send an email to [email protected] ruby-core info -- https://ml.ruby-lang.org/mailman3/lists/ruby-core.ml.ruby-lang.org/