Function _npy_alloc_cache

numpy/core/src/multiarray/alloc.c:91–123

* very simplistic small memory block cache to avoid more expensive libc * allocations * base function for data cache with 1 byte buckets and dimension cache with * sizeof(npy_intp) byte buckets */

 * sizeof(npy_intp) byte buckets
 */
static inline void *
_npy_alloc_cache(npy_uintp nelem, npy_uintp esz, npy_uint msz,
                 cache_bucket * cache, void * (*alloc)(size_t))
{
    void * p;
    assert((esz == 1 && cache == datacache) ||
           (esz == sizeof(npy_intp) && cache == dimcache));
    assert(PyGILState_Check());
    if (nelem < msz) {
        if (cache[nelem].available > 0) {
            return cache[nelem].ptrs[--(cache[nelem].available)];
        }
    }
    p = alloc(nelem * esz);
    if (p) {
#ifdef _PyPyGC_AddMemoryPressure
        _PyPyPyGC_AddMemoryPressure(nelem * esz);
#endif
#ifdef NPY_OS_LINUX
        /* allow kernel allocating huge pages for large arrays */
        if (NPY_UNLIKELY(nelem * esz >= ((1u<<22u))) && _madvise_hugepage) {
            npy_uintp offset = 4096u - (npy_uintp)p % (4096u);
            npy_uintp length = nelem * esz - offset;
            /**
             * Intentionally not checking for errors that may be returned by
             * older kernel versions; optimistically tries enabling huge pages.
             */
            madvise((void*)((npy_uintp)p + offset), length, MADV_HUGEPAGE);
        }
#endif
    }
    return p;
}

/*
 * return pointer p to cache, nelem is number of elements of the cache bucket