On Mon, 04 Apr 2011 20:59:52 -0700, geremy condra wrote: > On Mon, Apr 4, 2011 at 7:45 PM, Steven D'Aprano > <steve+comp.lang.pyt...@pearwood.info> wrote:
>> * The disclaimers about timing code snippets that can be found in the >> timeit module apply. If possible, use timeit rather than roll-you-own >> timers. > > Huh. In looking into timing attacks actually one of the biggest lessons > I learned was *not* to use timeit- that the overhead and variance > involved in using it will wind up consuming small changes in behavior in > ways that are fairly opaque until you really take it apart. Do you have more details? I follow the advice in the timeit module, and only ever look at the minimum value, and never try to calculate a mean or variance. Given the number of outside influences ("What do you mean starting up a browser with 200 tabs at the same time will affect the timing?"), I wouldn't trust a mean or variance to be meaningful. -- Steven -- http://mail.python.org/mailman/listinfo/python-list