C ++自定义内存管理使用brk（）系统调用来分配内存？

Question

I wrote a basic custom memory management allocator which would grab a chunk of memory, pre-create X objects so that whenever I needed to "create" an object I could grab one of the pre-created ones and simply assign data members (memory was already allocated).

I used placement-new :

//Grab a chunk of memory
char* buf = new char [sizeof(X) * num_objs]; 

//Pre-create a lot of objects
for(std::int64_t i=0; i<num_objs; i++){
    char* c = buf + (sizeof(X) * i);

    //This line creates the Order object at location c
    X* x = new(c)X;
}

//Assign data members to objects
for(std::int64_t i=0; i<num_objs; i++){
    char* buf_loc = buf + (sizeof(X) * i); 
    X* my_x = reinterpret_cast <X*> (buf_loc);
    my_x->a = 1;
    my_x->b = 2;
    my_x->c = 3;
    my_x->d = 4;
}

How easy/practical would it be to change the above and directly grab memory from the OS using brk() ?

Answer 1

Using brk will probably interfere with the regular C/C++ memory allocator. Even if you don't use regular new or malloc() in your code, it might be used in libraries.

If you want to manage your own memory, use mmap() on /dev/zero to get an empty block of memory. I think you can do this repeatedly to get new blocks.