This example really helped me understand how shared memory workes for blocks and threads. So, since all threads in a block must be run concurrently, if a block uses more shared memory than exists it will not be possible to run the block. Also, allocating too much shared memory in a block with few threads will dramatically affect performance of your program, since it limits the number of blocks (and therefore threads) which can be scheduled on a core.
This example really helped me understand how shared memory workes for blocks and threads. So, since all threads in a block must be run concurrently, if a block uses more shared memory than exists it will not be possible to run the block. Also, allocating too much shared memory in a block with few threads will dramatically affect performance of your program, since it limits the number of blocks (and therefore threads) which can be scheduled on a core.
Excellent comment @uncreative. Very precise.