Which option would you consider first to decrease the wait event immediately?

In a recent Automatic Workload Repository (AWR) report for your database, you notice a high
number of buffer busy waits. The database consists of locally managed tablespaces with free list
managed segments.
On further investigation, you find that buffer busy waits is caused by contention on data blocks.
Which option would you consider first to decrease the wait event immediately?

A.
Decreasing PCTUSED

B.
Decreasing PCTFREE

C.
Increasing the number of DBWN process

D.
Using Automatic Segment Space Management (ASSM)

E.
Increasing db_buffer_cache based on the V$DB_CACHE_ADVICE recommendation

Explanation:
* Automatic segment space management (ASSM) is a simpler and more efficient
way of managing space within a segment. It completely eliminates any need to specify and tune
the pctused,freelists, and freelist groups storage parameters for schema objects created in the
tablespace. If any of these attributes are specified, they are ignored.
* Oracle introduced Automatic Segment Storage Management (ASSM) as a replacement for
traditional freelists management which used one-way linked-lists to manage free blocks with tables
and indexes. ASSM is commonly called “bitmap freelists” because that is how Oracle implement
the internal data structures for free block management.
Note:

* Buffer busy waits are most commonly associated with segment header contention onside the
data buffer pool (db_cache_size, etc.).
* The most common remedies for high buffer busy waits include database writer (DBWR)
contention tuning, adding freelists (or ASSM), and adding missing indexes.