CPU and Memory usage of a method call in iPhone

Question

I am trying to add some performance stats to a method call for my iPhone app. I used the following to find the time to process:

#define TICK   NSDate *startTime = [NSDate date]
#define TOCK   NSLog(@"Time to process: %f", -[startTime timeIntervalSinceNow])

Are there similar strategies to measure CPU and memory usage of a method call?

Answer 1

Use Instruments to check your app's performance. Apple has done a pretty decent job, so no need to reinvent the wheel.

Answer 2

使用仪器在真实设备上实际使用这些测量。

Answer 3

You are going to have to do some work to get this working but here's how you can do it.

• From this SO answer you can learn how to get the current CPU usage.
• From this SO answer you can learn how to get the current Memory usage.

Now you can spawn a new thread that checks the CPU and memory periodically or on-demand, then create a class, something like this:

@interface ProfilerBlock
-(id) init;
-(void) end;
@end

• The init method should initialize the current time and register the ProfilerBlock instance to get information from the worker thread about memory usage and CPU usage.
• The end method should calculate the time and print all the needed information or write it to a file or something :)

Now create a C-Style releasing function for the ProfilerBlock class

static void __$_Profiler_Block_Release_Object_$__(ProfilerBlock **obj) // the long name is just to prevent duplicated symbol names //
{
    [(*obj) end];
    [(*obj) release];
    (*obj) = nil;
}

Finally you can create macros to make your life easier:

#define CONCAT2(x, y) x ## y
#define CONCAT(x, y) CONCAT2(x, y)
#define PROFILER_SCOPE_OBJECT __attribute__((cleanup(__$_Profiler_Block_Release_Object_$__)))
#define PROFILE_BLOCK ProfilerBlock *CONCAT(__profilerBlock_, __LINE__) PROFILER_SCOPE_OBJECT = [[ProfilerBlock alloc] init];

Once you have all this, you can profile methods like this:

-(void) methodToProfile
{
    PROFILE_BLOCK
    // add some code to profile here //
    // the "end" function will get called automatically after the method is done, even if you return early, allowing you to process the profiled data //
}

I hope this helps, sorry if I didn't go in detail about how to meassure memory and CPU but I believe it is well covered in the other answers.

Answer 4

 NSTimeInterval t1 = [[NSDate date] timeIntervalSince1970];

.... custom processes ...

 NSTimeInterval t2 = [[NSDate date] timeIntervalSince1970];
 NSTimeInterval dt = t2-t1; this is in milisec;