The housekeeper wash
task (which sp_who reports as HK
WASH) typically runs as a low-priority task,
and runs only during idle cycles when Adaptive Server has no user
tasks to process. While running, the wash task automatically writes dirty
buffers to disk (called free writes) and performs other maintenance
tasks. These writes result in improved CPU utilization and a decreased
need for buffer washing during transaction processing. They also
reduce the number and duration of checkpoint spikes— times
when the checkpoint process causes a short, sharp rise in disk writes.
By default, the housekeeper garbage collection operates at the priority level of an ordinary user and cleans up data that was logically deleted and resets the rows so the tables have space again. If Adaptive Server is configured for threaded mode, use sp_bindexeclass or sp_setpsexe to set the housekeeper task to a higher priority level.
See Chapter 11, “Diagnosing System Problems,” in the System Administration Guide: Volume 1 for more information on the housekeeper tasks and for information about resetting their priorities.
