Re: time system call expensive?

[Akos Marton <makos999@gmail.com>]

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I advice you `man 3 clock`.
If you want to get much more precision the attached project can help you.
Does it help?

Regards,
mAkos


Michal Nazarewicz wrote:
> On Thu, 21 Jul 2011 06:41:14 +0200, Vadiraj <vadiraj.cs@gmail.com> wrote:
>> I'm evaluating time consumed by method. I'm using time(NULL) system
>> call to capture time before and after the call to the function.
>> Just wanted to know if this has a considerable performance hit? For
>> all I believe time syscall is quite optimized and should not really be
>> matter of concern.
>>
>> Please let me know if someone have evaluated time(NULL) system over head..
>>
>> Assuming the method I'm evaluating is a frequently called method.
> 
> Why do you worry about it?  What do you need the time for?  If are
> really using time(2) it means that the function you're calling run time
> is counted in seconds.  If that's the case, two call to time(2) are
> by all means negligible.
> 
> If you need in for benchmark, you would probably do something like:
> 
> start = time(NULL)
> for (vary big number)
>     call function you benchmark
> end = time(NULL)
> 
> In either case, you should check gettimeofday(2).
> 


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