Matt Rajca

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Quick and Dirty Profiling with Blocks

July 01, 2011

Instruments is an amazing tool for finding all sorts of performance issues in software, but sometimes, all you want to do is log a quick and dirty timing of a snippet of code.

Mark Darlymple once posted a quickie that does just this. Unfortunately, the code isn't very reusable. You have to wrap each chunk of code you want to profile with nearly 8 lines of boilerplate code.

We can reduce some of this complexity by writing a profile function that takes a block of work as an argument instead.

    
    void profile (const char *name, void (^work) (void)) {
        struct timeval start, end;
        gettimeofday (&start, NULL);
        
        work();
        
        gettimeofday (&end, NULL);
        
        double fstart = (start.tv_sec * 1000000.0 + start.tv_usec) / 1000000.0;
        double fend = (end.tv_sec * 1000000.0 + end.tv_usec) / 1000000.0;
        
        printf("%s took %f seconds", name, fend - fstart);
    }
    

Now, all we have to do is call profile and pass in the block we wish to time; the timing will get logged to standard out.

    
    profile("Long Task", ^{ performLongTask(); } );