From: "jcole1989 (James Coleman)" <jtc331@...>
Date: 2013-02-28T13:22:44+09:00
Subject: [ruby-core:53025] [Backport 200 - Backport #7984][Open] Severe speed issues in 2.0.0 compiled with Clang


Issue #7984 has been reported by jcole1989 (James Coleman).

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Backport #7984: Severe speed issues in 2.0.0 compiled with Clang
https://bugs.ruby-lang.org/issues/7984

Author: jcole1989 (James Coleman)
Status: Open
Priority: High
Assignee: 
Category: 
Target version: 


I've been comparing Ruby 2.0.0 with 1.9.3-head, both compiled with the same basic set of CFLAGs with Clang on Mac OS 10.8 (Mountain Lion). A decent sized rails app was showing performance degradations, so I looked into the most basic of (micro)benchmarks. Running the following:

t = Benchmark.measure do
  50000000.times { Object.new }
end

Gives me the following output:

1.9.3-head: 11.240000 0.000000 11.240000 ( 11.247285)
2.0.0p0: 23.610000 0.010000 23.620000 ( 23.629643)

Ruby 2.0.0 takes over twice as long as 1.9.3. In contrast, running the same test under rubies compiled with GCC on linux (unfortunately I can't do a direct test on OSX because 2.0.0 currently won't compile under the current apple gcc 4.2) Ruby 2.0.0 shows a 15-20% speed improvement over 1.9.3.

So it seems there's a severe speed regression interaction with the ruby 2.0.0 code and Clang.


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