From: Earle Clubb <eclubb@...>
Date: 2007-05-07T23:28:55+09:00
Subject: Re: 10 millisecond delay/callback


> I consistently get precise timings off of it, just like that.  I do not,
> however, on another box -- a newer 64 bit dual core AMD, also running
> Linux.  On that box a wait of 0.01 seems to fairly consistently wait 
> about
> 0.012.
> 
> I think that is about as precise as one is going to make the timings, 
> with
> Ruby, in any case, though.
> 
> 
> Kirk Haines

So I've done some more testing and I found something interesting:

Code:
#!/usr/bin/ruby -w

require 'enumerator'

a = []
15.times do
  sleep 0.008000499999999999
# sleep 0.0080004999999999999
  a << Time.now.usec / 1000.0
end
a.each_cons(2) {|x,y| puts y-x}


Results:
6.14199999999994
8.15700000000004
7.798
8.03800000000001
8.04099999999994
7.93900000000008
8.072
7.91099999999994
8.05799999999999
7.94299999999998
8.0
8.005
7.995
8.00100000000009

Now if use the second sleep expression instead of the first, I get the 
following results:
11.978
12.016
11.963
12.073
11.939
12.06
12.235
11.696
12.0
12.047
11.956
12.004
11.996
12.0

Can anyone explain why the delay jumps from ~8ms to ~12ms?  I think this 
may be the root of my problem.

Thanks,
Earle

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