Two main latches protect data blocks in the buffer cache. The cache buffer LRU chain latch must be obtained in order to introduce a new block into the buffer cache, and when writing a buffer back to disk.
A cache buffer chains latch is acquired whenever a block in the buffer cache is accessed (pinned).
Contention for these latches usually typifies a database that has very high I/O rates. It is possible to reduce contention for the cache buffer LRU chain latch by increasing the size of the buffer cache. This reduces the rate at which new blocks are introduced into the buffer cache.
Reducing contention for the cache buffer chains latch usually requires the reduction of logical I/O rates (by tuning and minimizing the I/O requirements of application SQL).
You can create additional cache buffer LRU chain latches by adjusting the hidden configuration parameter _DB_BLOCK_LRU_LATCHES.
You can reduce the load on the cache buffer chain latches by increasing the value of the hidden configuration parameter _DB_BLOCK_HASH_BUCKETS.
For more information on improving latch performance, see the Tuning | Latch Page.
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