Re: [boost] proposal - Statistically robust function timing for performance decisions.

Subject: Re: [boost] proposal - Statistically robust function timing for performance decisions.
From: Matthias Troyer (troyer_at_[hidden])
Date: 2009-07-29 02:06:41

On 19 Jul 2009, at 16:00, Edward Grace wrote:

>
> On 19 Jul 2009, at 22:15, Mathias Gaunard wrote:
>
>> Edward Grace wrote:
>>
>>> I modified the example to force side-effects by making the  
>>> variables in
>>> the loop global.  Consequently it now doesn't get optimised away -
>>> compilers sure are clever these days.
>>
>> Rather, I think you should use volatile or something, which is
>> guaranteed by the C++ standard not be optimized out.
>
> Nice idea.  I wondered if it could be applied to functions or  
> function pointers.  I'm not convinced it's properly supported in  
> this context.  Anyhow, I think a 'global variable' trick works. A  
> more elegant solution is welcome!

Volatile will have more side effects and prevent optimization that we  
might want the compiler to make