Using Shark to profile and optimize your code!

First and Foremost

Shark is an incredible FREE tool for profiling code. You can get into the nitty gritty of what parts of your code aren't working and where you need to optimize. It will tell you which functions in your code are taking up the most processing and provide suggestions on what to change!

• Read this tutorial on using Shark with Xcode for VSTs! It's the only one like it I could find: http://www.niallmoody.com/ndcplugs/xcodetutorial.htm
  
• For additional information, follow through this tutorial on the apple developer site: http://developer.apple.com/tools/sharkoptimize.html.

Setting this up is really not THAT painful

Location: If you downloaded the developer's tools that come with the Mac, you should already have Shark available here: /Developer/Applications/Performance Tools/Shark.app

Other Things You Need: A reliable vst host, Xcode and some knowledge to tie this all together.

1. Understand your Xcode build configurations: http://developer.apple.com/documentation/DeveloperTools/Conceptual/XcodeBuildSystem/400-Build_Configurations/build_configs.html

• You may have multiple build configurations that perform different duties for you. A typical setup has Debug and Release configurations. The main differences are that a Debug configuration turns off compiler optimizations and specifies a different build path. You can customize these configurations to perform different functions. You can do this by right clicking on your target and selecting "Get Info". Click on the Build tab and voila. You can change any parameter in the build configuration you select, or across all build configurations. You can even create new build configurations by right clicking on the entire project and getting info, then selecting the "Configurations" tab.

2. Setup your Xcode Release build configuration

• You will typically want to profile your plug-in with all the compiler optimizations, etc. turned on. This way, you will know exactly how your end user will experience the deployed plug-in. There are a number of steps to set up your build configuration appropriately. These are all stolen from the niallmoody website noted above. Once again, I will mention that this site is AWESOME!
  1. Set your build configuration to Release
  2. Set the 'Generate Profiling Code' option to true in your target's info window.
  3. Set your 'Other C Flags' to -g-full. Be careful when you set this. Xcode will automatically set the flags for C++ too. Be sure this is not happening, or else you will run into build errors.

3. Setup Xcode to launch your VST host when you want to profile the code

• In the Project menu, select 'New Custom Executable'. Point it to your host, give it a name and you're done. I am using Bias Peak as a host because it loads quickly, but any one will do just fine.

You're ready to start optimizing!!

The Profiling Process

1. In Xcode, click the Debug icon (the yellow spray can) or go to the Build Menu...Build and Go (debug). Your code will compile and your VST host will magically start running.

2. Start your plug-in running in the host.

3. Open Shark

4. In Shark's window, set the combo boxes to (from left to right): Time Profile, Process and the name of your VST host process that is running.

5. Press Start on Shark and it will begin sampling and profiling your code. When it is done, it will open a window of its results as shown below:

Process Output Window After Sampling

6. You will see your processReplacing function in the list. Click on it and your function's code will be revealed with statistics. If there were any problems or places where your code could be optimized, an ! will show up in the fourth column. You can click this to get suggestions on how to optimize your code!

Your Function's Code reviewed by Shark!

HAVE FUN!