[lwip-users] MEMP_MEM_MALLOC

[Giuseppe Modugno]

I'm thinking if it's better to set MEMP_MEM_MALLOC or not in my application. I'm working with MEMP_MEM_MALLOC=1 (I started from an example) and it works. However I'm not sure it's the best choice for me.

So what are the arguments for and against MEMP_MEM_MALLOC?

This is what I have understood:

• lwip *always* uses pools for some dynamic data (for example UDP PCBs and timeouts);
• pools have a *fixed* number for maximum allocated elements (for example, MEMP_NUM_SYS_TIMEOUT for timeouts);
  
• (MEMP_MEM_MALLOC=0): all the elements of the pools are statically allocated (so they're not in the heap);
  
• (MEMP_MEM_MALLOC=1): the elements of the pools aren't statically allocated, but they're (de)allocated at run-time with malloc/free, when needed;
  
• allocation of an element is much more fast if MEMP_MEM_MALLOC=0 (otherwise malloc/free are used);
• MEMP_MEM_MALLOC=0 is a good choice if available malloc/free are poor (in my case, I'm using newlib on Cortex-M3... I don't really know if it's a good implementation or not).

What are your suggestions?