how bad is it to use dynamic datastuctures on an embedded system?

Question

So in an embedded systems unit, that i\'m taking at uni next year, we will learn that dynamic data structures are a bad thing to have in an embedded system program. but the

Answer 1

Well, many smaller microcontrollers don't have anything like an MMU, or an OS with a nice heap for you to work with.

For those that do, as long as you keep a sane bound on the amount of memory you are asking for, I don't really see a huge problem with it.

However, many embedded systems are also Real Time systems. If your application has hard deadlines for how long it can take to run, you will have trouble with dynamic allocations. Most heap implementations use algorithims that don't have a very well-bounded runtime. In some (perhaps rare) instances, they will take waaaay longer to run than normal. There are some real-time heap implementations, but they aren't in very wide use. The general rule is to avoid any dynamic allocation or deallocation in a hard real-time system after initialization.