Performance Tuning

Static vs. Dynamic Linking

A lot of CPU and memory is used by the ELF (Executable and Linking Format) linking process. Significant savings can be achieved by using a static build of the application suite.

This means that rather than having dynamic Qt libraries and a collection of executables which link dynamically to these libraries, all the applications is built into into a single executable which is statically linked to static Qt libraries.

This improves the start-up time and reduces memory usage, at the expense of flexibility (to add a new application, you must recompile the single executable) and robustness (if one application has a bug, it might harm other applications).

    ./configure -static

The Qtopia platform is an example using this apporach: It can be built either as a set of dynamically linked executables, or as a single static application.

When installing end-user applications, this approach may not be an option, but when building a single application suite for a device with limited CPU power and memory, this option could be very beneficial.

    void *operator new[](size_t size)
    {
        return malloc(size);
    }

    void *operator new(size_t size)
    {
        return malloc(size);
    }

    void operator delete[](void *ptr)
    {
        free(ptr);
    }

    void operator delete[](void *ptr, size_t)
    {
        free(ptr);
    }

    void operator delete(void *ptr)
    {
        free(ptr);
    }

    void operator delete(void *ptr, size_t)
    {
        free(ptr);
    }