What is the practical meaning of SL_INDEX_COUNT_LOG2?

[kisvegabor]

Hi,

I made a test with an 64 bit i5 CPU using 1MB pool size with different SL_INDEX_COUNT_LOG2 settings and allocation sizes.

The algorithm:

    size_t alloc_size = 1; //or 8 or 1024;
    void * p;
    uint32_t c = 0;
    do {
        p = lv_mem_alloc(alloc_size); //Just a wrapper around tlsf_alloc
        c++;
    }while(p);

    //Uses lv_tlsf_walk_pool to get some memory info
    lv_mem_monitor_t m;
    lv_mem_monitor(&m);

    printf("count: %d, free: %d\n", c, m.free_size);
    return 0;

The results:
alloc_size=1

• SL_INDEX_COUNT_LOG=5 count: 32415, free: 0
• SL_INDEX_COUNT_LOG=1 count: 32510, free: 0

alloc_size=8

• SL_INDEX_COUNT_LOG=5 count: 32415, free: 0
• SL_INDEX_COUNT_LOG=1 count: 32510, free: 0

alloc_size=1024

• SL_INDEX_COUNT_LOG=5 count: 1006, free: 80
• SL_INDEX_COUNT_LOG=1 count: 1009, free: 24

So with SL_INDEX_COUNT_LOG=1 always more blocks were allocated, I guess it's because of the smaller control_t overhead.

Hence, SL_INDEX_COUNT_LOG=1 always seems better than 5, but I probably I miss something. Could you comment on this?