How much does memory fragmentation slow down the system and application?

Question

Performance evaluation

The question is about the garbage collector. As I understand it, a good GC can perform memory defragmentation i.e. after the object is removed from memory, the freed holes are eliminated.
Actually, the question is how much manual memory management leads to fragmentation (it is unlikely that most programmers do anything more than simply delete an object).
How much is the performance drop? Where can I read more about this.
In what tasks did you encounter memory fragmentation problems?

Answer 1

The impact of memory fragmentation on performance is well expressed in those systems where there are significant delays in accessing memory before performing reads and writes. Therefore, for hard drives, there is a defragmentation service. And for memory such as RAM, this is unnecessary and harmful. Because the processor will have to flush its address translation cache again. And it will take much more time. Because in terms of address translation, there is no memory fragmentation. That is, each task sees the memory not littered and linear. And the paging organization of memory allows programmers to live better. Another thing is the segmental organization of memory. But they have not been used for a long time. Garbage collectors do a few other things. Their task is to clear the memory of unused objects for such and such a time, so that later there is no problem with the availability of memory for various operations. Otherwise, a memory leak will occur. But they don't do defragmentation.

Answer 2

It is correct to call it "Address space fragmentation". There really is a problem on a 32-bit system, and, depending on the task, a speed landing may come out.
On a 64-bit system, the address space is huge and hard to fragment.