Struct to store records from /proc/<pid>/maps

Question

I use the next struct to store information from /proc//maps:

typedef struct
{
    unsigned long vm_start;
    unsigned long vm_end;
    unsigned long vm_flags;
    unsigned long vm_pgoff;
    dev_t vm_dev;
    unsigned long vm_ino;
    unsigned long vm_size;
    int vm_shares;
} map_t;

And a vector:

typedef struct
{
    map_t *arr;
    int size;
    int reserved;
} map_vector_t;

When I read a record from file, I find a shared equivalent region:

int index = mem_mapping_find_shared(vector, map);
if (index != -1) {
    vector->arr[index].vm_shares++;
    continue;
}

map.vm_shares = 0;

int mem_mapping_find_shared(map_vector_t *vector, map_t map)
{
    int index = -1;

    for (int i = 0; index == -1 && i < vector->size; i++) {
        if (mem_mapping_is_shareable(vector->arr[i], map)) {
            index = i;
        }
    }

    return index;
}

But it's too slow code. I think I should use hash table, right? Which hash function I can use?

Answer 1

Maybe it will be useful for someone:

unsigned long long mem_mapping_hash(const map_t *map)
{
    unsigned long long h = map->vm_pgoff;
    h = h * PRIME + map->vm_dev;
    h = h * PRIME + map->vm_ino;
    h = h * PRIME + map->vm_size;

    return h % PRIME;
}