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Method for dedicated CPU interrupt tasking Disclosure Number: IPCOM000028085D
Original Publication Date: 2004-Apr-22
Included in the Prior Art Database: 2004-Apr-22
Document File: 1 page(s) / 30K

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A method for dedicating one or more processors in a multiprocessor system or logical partition to device interrupt handling, thereby reserving a known quantity of processing capacity for required I/O workloads.

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Method for dedicated CPU interrupt tasking

As the data throughput of Input/Output (I/O) technologies such as Ethernet* continues to grow, I/O devices are putting higher demands on system interrupt processing. The current AIX** system interrupt design typically dispatches the pending interrupt task to the next available processor. A significant issue with this approach is the associated context-swapping overhead that is incurred in order to service the interrupt when the next available processor is running a lower-priority thread.

Another significant issue is that I/O device driver interrupt routines must terminate in a finite period of time, regardless of whether the I/O task has actually completed, in order to avoid starvation of lower priority processes with respect to processor resources. This limits maximum data throughput and impacts some system performance metrics. In many cases, the I/O device must interrupt the host again since there is still data to transfer, which incurs yet more context-swapping overhead in order to service the interrupt. Meanwhile, other system tasks such as database applications must contend with I/O devices for the same processor resources, and if these tasks are running at the process level, they will be forced to yield processor time to I/O device interrupt tasks. By reserving one or more processors in a system or logical partition as dedicated device interrupt processors, I/O device driver interrupt routines can be permitted to r...