From: Alex Young <alex@...>
Date: 2007-08-02T03:12:35+09:00
Subject: Re: Performance diffrence between ifs and case

Gregory Brown wrote:
> On 7/31/07, Paul <Paul.McArdles@gmail.com> wrote:
>> def nop
>> end
>>
>>
>> Benchmark.bmbm(20) do |x|
>>    x.report("range"){for i in 0..1000000 do nop end}
>>    x.report("times"){1000000.times do nop end}
>>    x.report("each"){(0..1000000).each do nop end}
>> end
>> ------------------------------------------------
>> range     0.657000   0.000000   0.657000 (  0.656000)
>> times     0.609000   0.000000   0.609000 (  0.609000)
>> each      0.594000   0.000000   0.594000 (  0.594000)
>> ----------------------------- total: 1.860000sec
>>
>>          user     system      total        real
>> range     0.641000   0.000000   0.641000 (  0.640000)
>> times     0.594000   0.000000   0.594000 (  0.594000)
>> each      0.578000   0.000000   0.578000 (  0.594000)
> 
> I'll remember this next time I want to save 0.03 s per 1000000 iterations.
> 
> <groans>
> 
> My original point was that if you want to do something n times, use n.times
> :)
> 
My point was going to be that the one place optimisation really matters 
is in benchmark code - you only want to measure the effect you're 
looking for - but I managed to shoot myself in the foot and prove 
another point.  Don't assume, measure!  :-)

-- 
Alex