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Feature #10165

closed

Use Process.clock_gettime to speed up Benchmark.realtime.

Added by phiggins (Pete Higgins) over 8 years ago. Updated over 8 years ago.

Status:
Closed
Priority:
Normal
Assignee:
-
Target version:
-
[ruby-core:64511]

Description

This patch changes the Benchmark.realtime method to use the Process.clock_gettime internally when generating the time elapsed. Calling Process.clock_gettime is faster than the current way of creating Time objects.

I wrote a benchmark script (also attached) to demonstrate the difference:

require 'benchmark'

def old_benchmark
  r0 = Time.now
  yield
  Time.now - r0
end

def new_benchmark
  r0 = Process.clock_gettime(Process::CLOCK_MONOTONIC)
  yield
  Process.clock_gettime(Process::CLOCK_MONOTONIC) - r0
end

n = (ARGV.first || 1_000_000).to_i

puts "#{n} iterations."

Benchmark.bmbm do |b|
  b.report("old") { n.times { old_benchmark { nil } } }
  b.report("new") { n.times { new_benchmark { nil } } }
end

When I run this on my local machine I see this output:

1000000 iterations.
Rehearsal ---------------------------------------
old   0.860000   0.000000   0.860000 (  0.863118)
new   0.360000   0.000000   0.360000 (  0.355242)
------------------------------ total: 1.220000sec

          user     system      total        real
old   0.870000   0.010000   0.880000 (  0.866577)
new   0.330000   0.000000   0.330000 (  0.328982)

I discussed this idea originally with Eric Hodel, but he has not reviewed this code.


Files

benchmark_benchmark_realtime.rb (424 Bytes) benchmark_benchmark_realtime.rb phiggins (Pete Higgins), 08/23/2014 08:58 PM
faster_benchmark_realtime.diff (909 Bytes) faster_benchmark_realtime.diff phiggins (Pete Higgins), 08/23/2014 08:59 PM
faster_benchmark_realtime_2.diff (1.1 KB) faster_benchmark_realtime_2.diff phiggins (Pete Higgins), 08/24/2014 12:22 AM
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