"del buffer" dosen't work

[qing-2]

I run Session_4/4_basic_allocate_example.ipynb on my jupyter notebook.
The memory reduced even after del buffer
I don't know why and now I have to use the Linux command echo 1 > /proc/sys/vm/drop_caches on the terminal to free cache, but it's not useful all the time.
I have no idea what allocate have done to my ram.

[qing-2]

after adding gc , del works !!! ✌

inport allocate  # replace Xlnk
import gc

weight_buffer = allocate(shape=(25470896,), dtype=np.uint32)  # allocate 100M memory
params_w = np.fromfile("yolo.bin", dtype=np.uint32)      # read the file
np.copyto(weight_buffer, params_w)        # load the file to the 100M memory

del params_w        # will not be used again, so delete it to free memory
gc.collect()