4 Replies Latest reply on Dec 26, 2012 12:00 AM by kalyanpk

    Confusion about the performance counter

    acekiller

      Hi, I am working on a program written in OpenCL and running on Fusion APU (CPU+GPU on one die). I wan to get some performance counters such as instructions number, branch number and so on. I have two tools on hand: AMD APP Profiler and CodeAnalyst. When I use the APP Profiler, I found that it seems can only provide instructions counter for GPU, cannot for CPU. Then I use CodeAnalyst, but then three confusions occurred.

      1. On App Profiler, it can give the number of ALUInsts (i.e. the number of executed ALU instructions per work-item) is about 70000. The whole thread space on GPU has 8192 threads, so I intuitively think there are 70000 * 8192 instructions executed by GPU. Is that right?
      2. When I use CodeAnalyst to measure the instructions for the same program on CPU part, it just gave "Ret inst", "Ret branch"  such kind of counters, but I am not sure about one thing: this program runs on both CPU and GPU at the same time, what are these counters for? For CPU only, for GPU only? or the sum?
      3. No matter what these counters for, I found that the value of Ret Inst (i.e. retired instructions) is about 40000, it seems too small for the whole program, I guess the instructions for a program should be at order of billions, how it could be only 4w? The attached pic shows the results.

      Is there any people can help me resolve these confusions, I am just a tyro here, wish kind help from all of you. Thanks!