OT: recommended way of timing two pieces of code in C

[Ranjan Maitra]

On Fri, 26 Feb 2016 17:29:58 +0000 "Patrick O'Callaghan" <pocallaghan at gmail.com> wrote:

> On Fri, 2016-02-26 at 08:31 -0600, Ranjan Maitra wrote:
> > Hi,
> > 
> > Disclaimer: This is clearly marked OT, with the only connection to
> > this group being the fact that I am running F23 on a 20-core Dell
> > T5810 @3.1 GHz each and 64 GiB memory. My OT queries over the past 13
> > years (almost) here have elicited great wealth of information so I am
> > posing here.
> > 
> > So, I am trying to compare two kinds of methods in a C program. Both
> > are written as efficiently as possible (assumed because no point
> > otherwise). I would like to know which of these is more efficient. I
> > have been using get_rusage but I was wondering whether there is a
> > better way?
> 
> I don't claim to be an expert but at first glance I wonder if you've
> defined what you mean by efficiency. Execution time? Program size?
> Memory locality (affects virtual memory performance) etc.

I responded to this on another thread, but I am interested in the amount of time taken by a program in executing a set of instructions. If that includes memory allocation, etc, then fine. 


> You might want to read some of the extensive literature on
> benchmarking.

I have found the literature extremely confusing and unclear.

> 
> > Separately, is there a way to get the number of floating point
> > instructions in C? Both FLOPS and MIPS? 
> 
> Instructions executed on every code path? On the most likely code path?
> 
> Remember: MIPS = Meaningless Indicator of the Performance of Systems.
> 

OK, is there a way to calculate the FLOP instructions in C?

Many thanks and best wishes,
Ranjan

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