From: Eric Wong <normalperson@...>
Date: 2013-08-26T21:58:17+00:00
Subject: [ruby-core:56815] Re: [ruby-trunk - Feature #8820][Open] Speed up Array#index

Joel VanderWerf <joelvanderwerf@gmail.com> wrote:
> On 08/26/2013 12:57 PM, Eric Wong wrote:
> >The performance of your code varies between runs because the
> >ordering is always different and index is O(n) _worst_ case.
> >call srand(0) before any rand calls to get a consistent seed.
> 
> The running time of this code won't vary much at all. The n=10000000
> setting is much higher than a.size, so most #index calls will return
> nil. The entire array is searched for almost all iterations.

I think you're right.  I was on a new machine (Haswell) and enabled a
bunch kernel options I normally don't use (Hyper-threading,
full tickless, full preempt, automatic process group scheduling).
Lots of variables even when the system isn't loaded :o