1. Field of the Invention
The current invention generally relates to digital logic systems. More specifically, the current invention relates to capacity on demand using control over latency and bandwidth of signal bussing.
2. Description of the Related Art
Computing systems are currently available that provide capacity on demand. Capacity is used to denote a performance characteristic of a computing system. For example, in a commercial workload, ability to handle some number of “transactions per minute” is one measure of capacity. Ability to provide a fast response time to a request is another measurement of capacity. Ability to perform some number of floating point operations per second is a third example of capacity. Demand is the workload being placed on the computing system. A computing system having a large capacity but only seeing a small demand is wasteful and expensive. A computing system having a demand higher than a capacity provides slow response to the user. Demand tends to vary greatly during a day or day of week (e.g., in many cases, during weekends, demand is low on many computing systems).
IBM Corporation of Armonk, N.Y., currently provides capacity on demand (COD), which is sometimes called Capacity Upgrade on Demand (CUoD), for IBM eServer pSeries p650, 670 and 690 computing systems. Reference “pSeries Capacity Upgrade on Demand advantages” viewable at the following URL:
http://www-8.ibm.com/servers/eserver/au/pseries/cuod/advantages.html
This capability allows a customer to accommodate unexpected demands on a computing system installed. For example, pSeries 670 and 690 servers are available in units of four active and four inactive processors with up to 50% of the system in standby. As workload demands require more processing power, unused processors can be activated simply by placing an order to activate the additional processors, sending current system configuration to an authorizing source and receiving over the internet an electronically encrypted activation key which unlocks the desired amount of processors. There is no hardware to ship and install, and no additional contract is required. Memory activation works the same way. CUOD is available in various sizes for the p650, p670 and p690 systems. Activation in 4 GB (Gigabyte) increments is made by ordering an activation key to unlock the desired amount of memory.
Providing CUoD by enabling entire processors limits granularity of capacity upgrades (or reductions). For example, in a computing system having four active processors, the smallest increment in capacity is one processor.
Providing CUoD by adding a processor, in some computing environments, may not provide a proportional increase in capacity. For example, if a computing system is running a numerically intensive program and an improvement in that numerically intensive program is desired, adding a processor will not provide the desired improvement, unless the numerically intensive program is capable of distribution across more than one processor. Adding a large increment of memory may not be of much help in the numerically intensive program, either, since many such programs make extensive use of a relatively small amount of memory, and bandwidth, rather than total memory size, is the dominant consideration.
Additional references include patent applications filed by the current assignee of the present patent application include: Ser. No. 10/616,676, “Apparatus and Method for Providing Metered Capacity of Computer Resources”, by Daniel C. Birkestrand et al, filed Jul. 10, 2003; Ser. No. 10/406,164, “Billing Information Authentication for On-Demand Resources”, by Daniel C. Birkestrand et al, filed Apr. 03, 2003; and Ser. No. 10/640,541, “Capacity On Demand Grace Period for Incompliant System Configurations”, by Daniel C. Birkestrand et al, filed Aug. 28, 2003.
Therefore, there is a need for a method and apparatus to provide a finer granularity of capacity on demand.