benchmark

补丁补丁

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2 楼 Hooopo 2009-08-31  

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This report shows the user CPU time, system CPU time, the sum of 
#   the user and system CPU times, and the elapsed real time. The unit 
#   of time is seconds. 

1 楼 Hooopo 2009-08-31  

=begin
#
# benchmark.rb - a performance benchmarking library 
# 
# $Id: benchmark.rb 11708 2007-02-12 23:01:19Z shyouhei $
# 
# Created by Gotoken ([e-mail]). 
#
# Documentation by Gotoken (original RD), Lyle Johnson (RDoc conversion), and
# Gavin Sinclair (editing). 
#
=end

# == Overview
#
# The Benchmark module provides methods for benchmarking Ruby code, giving
# detailed reports on the time taken for each task.
#

# The Benchmark module provides methods to measure and report the time
# used to execute Ruby code.
#
# * Measure the time to construct the string given by the expression
#   <tt>"a"*1_000_000</tt>:
#
#       require 'benchmark'
#
#       puts Benchmark.measure { "a"*1_000_000 }
# 
#   On my machine (FreeBSD 3.2 on P5, 100MHz) this generates:
# 
#       1.166667   0.050000   1.216667 (  0.571355)
# 
#   This report shows the user CPU time, system CPU time, the sum of
#   the user and system CPU times, and the elapsed real time. The unit
#   of time is seconds.
# 
# * Do some experiments sequentially using the #bm method:
#
#       require 'benchmark'
#
#       n = 50000
#       Benchmark.bm do |x|
#         x.report { for i in 1..n; a = "1"; end }
#         x.report { n.times do   ; a = "1"; end }
#         x.report { 1.upto(n) do ; a = "1"; end }
#       end
# 
#   The result:
#
#              user     system      total        real
#          1.033333   0.016667   1.016667 (  0.492106)
#          1.483333   0.000000   1.483333 (  0.694605)
#          1.516667   0.000000   1.516667 (  0.711077)
#
# * Continuing the previous example, put a label in each report:
#
#       require 'benchmark'
#
#       n = 50000
#       Benchmark.bm(7) do |x|
#         x.report("for:")   { for i in 1..n; a = "1"; end }
#         x.report("times:") { n.times do   ; a = "1"; end }
#         x.report("upto:")  { 1.upto(n) do ; a = "1"; end }
#       end
# 
# The result:
# 
#                     user     system      total        real
#        for:     1.050000   0.000000   1.050000 (  0.503462)
#        times:   1.533333   0.016667   1.550000 (  0.735473)
#        upto:    1.500000   0.016667   1.516667 (  0.711239)
# 
#
# * The times for some benchmarks depend on the order in which items
#   are run.  These differences are due to the cost of memory
#   allocation and garbage collection. To avoid these discrepancies,
#   the #bmbm method is provided.  For example, to compare ways to
#   sort an array of floats:
#
#       require 'benchmark'
#       
#       array = (1..1000000).map { rand }
#       
#       Benchmark.bmbm do |x|
#         x.report("sort!") { array.dup.sort! }
#         x.report("sort")  { array.dup.sort  }
#       end
# 
#   The result:
# 
#        Rehearsal -----------------------------------------
#        sort!  11.928000   0.010000  11.938000 ( 12.756000)
#        sort   13.048000   0.020000  13.068000 ( 13.857000)
#        ------------------------------- total: 25.006000sec
#        
#                    user     system      total        real
#        sort!  12.959000   0.010000  12.969000 ( 13.793000)
#        sort   12.007000   0.000000  12.007000 ( 12.791000)
#
#
# * Report statistics of sequential experiments with unique labels,
#   using the #benchmark method:
#
#       require 'benchmark'
#
#       n = 50000
#       Benchmark.benchmark(" "*7 + CAPTION, 7, FMTSTR, ">total:", ">avg:") do |x|
#         tf = x.report("for:")   { for i in 1..n; a = "1"; end }
#         tt = x.report("times:") { n.times do   ; a = "1"; end }
#         tu = x.report("upto:")  { 1.upto(n) do ; a = "1"; end }
#         [tf+tt+tu, (tf+tt+tu)/3]
#       end
# 
#   The result:
# 
#                     user     system      total        real
#        for:     1.016667   0.016667   1.033333 (  0.485749)
#        times:   1.450000   0.016667   1.466667 (  0.681367)
#        upto:    1.533333   0.000000   1.533333 (  0.722166)
#        >total:  4.000000   0.033333   4.033333 (  1.889282)
#        >avg:    1.333333   0.011111   1.344444 (  0.629761)