BitMagic Library Blog

Thursday, March 18, 2010

AMD CodeAnalyst Performance Analyzer for Windows®

Sharing some experience with AMD CodeAnalyst profiler.

This profiler from AMD is free, simple, lightweight and implemented as a Visual Studio plugin (apparently there is Linux version, but I did not try it yet).
Default profiling mode is time-sampling.

I took a few screenshots:

From Blog

From Blog

Pros and Cons:

1. Easy to use, you can start your session in a few minutes (+)
2. Hot-spot detection is easy, chart based, results are generally believable (+)
3. Profiler is lean and works fast, profiled program is not slowed down. (+)
3. AMD CodeAnalyst is free (+)
4. Different screens (chart and data) sometimes give contradicting results, which is a bit confusing. (-)
   In the screenshots above 1 and 3 indicate different proportion in hot-spot data (maybe I don't understand something or bug in visualization).
5. I failed to get call stack for hot-spots even though configuration promised to collect it. (-)
   This can be a big issue for large projects with multiple code paths.
   Similar tools like Intel Parallel Studio can show call stacks and allows easy call stack analysis.

http://developer.amd.com/cpu/CodeAnalyst/codeanalystwindows/Pages/default.aspx

Monday, January 11, 2010

BitMagic included in the Softpedia Linux software database

http://linux.softpedia.com/get/Programming/Libraries/BitMagic-library-53513.shtml

Saturday, January 9, 2010

BitMagic library version 3.6.3 released

This release fixes critical bug in 64-bit mode (#define BM64OPT) and improves performance of bit-counting related operations.

Parallel superscalar bit-counting

While working on version 3.6.3 collective Internet wisdom brought yet another interesting bit-counting algorithm, which turns to be efficient for 64-bit systems with superscalar execution (a form of parallelizm, where linear code with data-independent instructions is actually executed in parallel).

This code below implements population count for 4 64-bit integers. (Tested with GCC 4.4.1 64-bit Linux). This becomes part of BM 3.6.3 (when SourceForge recovers from its (I hope temporary) down).

inline
unsigned bitcount64_4way(bm::id64_t x, bm::id64_t y,
                    bm::id64_t u, bm::id64_t v)
{
    const bm::id64_t m1 = 0x5555555555555555;
    const bm::id64_t m2 = 0x3333333333333333;
    const bm::id64_t m3 = 0x0F0F0F0F0F0F0F0F;
    const bm::id64_t m4 = 0x000000FF000000FF;

    x = x - ((x >> 1) & m1);
    y = y - ((y >> 1) & m1);
    u = u - ((u >> 1) & m1);
    v = v - ((v >> 1) & m1);
    x = (x & m2) + ((x >> 2) & m2);
    y = (y & m2) + ((y >> 2) & m2);
    u = (u & m2) + ((u >> 2) & m2);
    v = (v & m2) + ((v >> 2) & m2);
    x = x + y;
    u = u + v;
    x = (x & m3) + ((x >> 4) & m3);
    u = (u & m3) + ((u >> 4) & m3);
    x = x + u;
    x = x + (x >> 8);
    x = x + (x >> 16);
    x = x & m4;
    x = x + (x >> 32);
    return x & 0x000001FF;
}