High speed bus with flow control and extended burst enhancements
In a networked system, in which high speed busses interconnect sources and destinations of data, systems for and methods of flow control and extended burst transfers are described. The present invention is directed to a system for selectively varying the number of burst transfers used to transmit a block of data. The present invention is also directed to a method of selectively varying the number of burst transfers needed to transmit a block of data.
1. In a networked system comprising a sender and a receiver interconnected by one or more buses, either or both the sender and receiver including or comprising one or more processors, a system for selectively varying the number of burst transfers used to transmit a block of data between the sender and receiver based on a size of a fractional portion of the block of data comprising:
computer memory containing first logic executed by said processor for transmitting the block of data from the sender to the receiver as n bursts, with the fractional portion forming one of the n bursts, if the size of any the fractional burst in the n bursts portion exceeds a threshold level, wherein n is an integer of two or more; and
computer memory containing second logic executed by said processor for transmitting the block of data from the sender to the receiver as less than n bursts if the size of any the fractional burst in the n bursts portion is less than or equal to the threshold level, by extending at least one of the less than n bursts to include the fractional portion.
2. The system of claim 1 , wherein the second logic is configured to transmit the block of data as n−1 bursts of one or more predetermined sizes if the size of any fractional burst in the n bursts is less than or equal to the threshold level, the n−1 bursts comprising n−2 bursts of a first predetermined size, and one burst having a second predetermined extended size equal to the first predetermined size plus an amount sufficient to accommodate the size of the fractional burst.
3. The system of claim 2 , further comprising third logic for transmitting data representative of the size of a burst, and an indicator of whether the burst is an extended burst.
4. The system of claim 1 , embodied in a sender of data in the networked system.
5. The system of claim 2 , wherein the first predetermined size is 64 bytes, the second predetermined extended size of 80 bytes, and the threshold level is 16 bytes.
6. In a networked system, a method of selectively varying the number of burst transfers needed to transmit a block of data based on a size of a fractional portion of the block of data comprising the steps of:
transmitting the block of data as n bursts, with the fractional portion forming one of the n bursts, if the size of the fractional portion exceeds a threshold level, wherein n is an integer of two or more; and
transmitting the block of data as less than n bursts if the size of the fractional portion is less than or equal to the threshold level, by extending at least one of the less than n bursts to include the fractional portion.
7. The method of claim 6 , wherein the second transmitting step comprises transmitting the block of data as n−1 bursts of one or more predetermined sizes if the size of any fractional burst in the n bursts is less than or equal to the threshold level, the n−1 bursts comprising n−2 bursts of a first predetermined size, and one burst having a second predetermined extended size equal to the first predetermined size plus an amount sufficient to accommodate the size of the fractional burst.
8. The method of claim 7 , further comprising transmitting the size of the one burst and an indicator of whether the burst is an extended burst.
9. The method of claim 7 , wherein the first predetermined size is 64 bytes, the second predetermined extended size is 80 bytes, and the threshold level is 16 bytes.