Oracle9i Database: Performance Tuning (6)

Diagnosing Contention for Latches

• Cache buffer chains latch is accessed by server process when they are attempting to locate a data buffer cache. Wait for this latch indicates that some cached blocks are probably being repeatedly searched for in buffer cache.
• Cache Buffer LRU Chain latch is used to manage the blocks on the LRU list in the database buffer. This latch is used while the DBWn write the dirty buffers to the data files and when a server process is searching for a free buffer in the LRU list while reading data from data files.
• V$LATCH SPIN_GETS column : incremented when the latch is acquired on a spin after being unsuccessful
• The redo copy latch is accessed by the user’s server process when its redo records in the redo log buffer.