如何实现malloc和free？ [英] How are malloc and free implemented?

问题描述

我想实现自己的动态内存管理系统，以添加有助于在C ++中管理内存的新功能。

I want to implement my own dynamic memory management system in order to add new features that help to manage memory in C++.

我使用Windows（XP）和Linux （Ubuntu）。
需要什么来实现像'malloc'和'free'这样的函数？
我认为我必须使用最低级别的系统调用。

I use Windows (XP) and Linux (Ubuntu). What is needed to implement functions like 'malloc' and 'free'? I think that I have to use lowest level system calls.

对于Windows，我发现了GetProcessHeap，HeapAlloc，HeapCreate，HeapDestroy和HeapFree。

For Windows, I have found the functions: GetProcessHeap, HeapAlloc, HeapCreate, HeapDestroy and HeapFree.

对于Linux，我没有找到任何用于堆管理的系统调用。在Linux上，malloc和free是系统调用，不是吗？

For Linux, I have not found any system calls for heap management. On Linux, malloc and free are system calls, are not they?

感谢

C ++不提供垃圾回收器，垃圾回收器速度很慢。一些分配很容易释放，但是有一些分配需要一个垃圾收集器。

C++ does not provide garbage collector and garbage collector is slow. Some allocations are easy to free, but there are allocations that needs a garbage collector.

我想实现这些功能并添加新功能：

*每当调用free（）时，检查指针是否属于堆。

*帮助垃圾收集。我必须存储一些关于分配块的信息。

*使用多个堆（HeapCreate / HeapDestroy在Windows上）。

I want to implement these functions and add new features:
* Whenever free() be called, check if the pointer belongs to heap.
* Help with garbage collection. I have to store some information about the allocated block.
* Use multiple heaps (HeapCreate/HeapDestroy on Windows). I can delete an entire heap with its allocated blocks quickly.

推荐答案

在linux上，malloc和free不是系统调用。 malloc / free通过使用 brk 系统调用扩展和收缩数据段（以及通过 mmap - 并且malloc管理这些区域内的内存。有关基本信息，请参阅此处

On linux, malloc and free are not system calls. malloc/free obtains memory from the kernel by extending and shrinking(if it can) the data segment using the brk system calls as well as obtaining anonymous memory with mmap - and malloc manages memory within those regions. Some basic information any many great references can be found here

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