Qt for Embedded Linux 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; rather than having a collection of executables which link dynamically to Qt's libraries, all the applications is built into into a single executable which is statically linked to Qt's 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

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);
 }