Storage Compaction

• Departing jobs leave their space free
• New job (from queue) must be able to fill the space (i.e. must be either of smaller or same size as the departing job).
• Holes created in memory
• The idea of combining holes or slots together = Compaction
• Compaction : Move all occupied areas of store to one end - leaving one large free space for incoming jobs, instead of numerous small ones
• Must be performed on each new allocation of job to memory or completion of job from memory
• System must also maintain relocation information
• Wasteful of CPU ? Can take a long time to just do compaction and not any serious computation
• Also called - Garbage Collection - hours on early computers

  
Figure 6: Storage Compaction