Memory pools and buffers C++

Question

I have a few questions about buffers and memory pools i would like to have answered.

Say i have a server, sending and receiving ~50-100+ msg / second. All msgs come in various sizes. How would you go about it to make the best of the memory management here ? My original plan was using fixed sized buffer nodes, and pool them, something like:

struct buffer{
    uint8_t  data[512];
    uint32_t end;
    buffer*  next;
}
buffer* b = pool_get_new_buffer();

So when a msg is sent, i create one or more buffers depending on the size and link them together. This way i dont have be afraid of fragmentation in the pool it self. (or thats atleast what i think). But on small msg, its a waste of space.

But reading more and more and checking out code on the internet, it looks like nobody uses this approach at all. So what would be a better approach ? Allocating memory from the pool depending on msg size ?

EDIT: So what im after here is maybe a more indept comparison of the different approaches.

If i use the chained buffer approach im guessing i will keep fragmentation at its lowest but on the other hand i would guess that doing memcpy for every buffer in the chain comes at a cost as well. But then again, allocating a large enough buffer and doing a single memcpy must have its downsides as well, even though most people choose this approach anyway.