further reduce the interrupt overhead, the drive can withhold the interrupt with the task completed messages until it gathers many of them to send at once, allowing the operating system to notify many threads simultaneously that their tasks have been completed. If another task completes after such an interrupt is sent, the host bus adapter can concatenate the completion messages together if the first set of completion messages has not been sent to the CPU. This allows the hard disk firmware design to trade off disk performance against CPU utilization by determining when to withhold and when to send completion messages. References External links Can Command Queuing Turbo Charge SATA? by Patrick Schmid, and Achim Roos of Tom's Hardware Guide AT Attachment SCSI Serial ATA