Method and apparatus for pacing the flow of information sent from a device

Abstract

Methods and apparatuses are disclosed for pacing the rate at which packets of one or more information streams are sent from a device, such as, for example, a workstation, computer, communications mechanism, or component thereof. Typically, multiple timing wheels each having a different timing granularity are used to schedule the transmission of packets of information corresponding the to the information streams. Using multiple timing wheels in this manner allows scheduling of a larger range of rates while typically using a significantly smaller amount of memory than a single timing wheel covering the same range of rates. An entry, corresponding to a next portion of an information stream to be sent from the device, is inserted into the timing wheels at a target time for sending the information. At the target time, the entry is removed and placed in a transmit list of items to be sent from the device. In one implementation a single transmit list is used for all timing wheels. In another implementation, multiple transmit lists are used, typically one for each timing wheel. Entries corresponding to portions of the information streams to be sent from the device are removed in a queued or target transmission time order from a transmit list. A packet of information corresponding to a removed entry is sent, and the entry itself is re-inserted in a timing wheel for the determined next transmission target time.