Direct memory access buffer management

摘要

Disclosed are systems and methods for reclaiming posted buffers during a direct memory access (DMA) operation executed by an input/output device (I/O device) in connection with data transfer across a network. During the data transfer, the I/O device may cancel a buffer provided by a device driver thereby relinquishing ownership of the buffer. A condition for the I/O device relinquishing ownership of a buffer may be provided by a distance vector that may be associated with the buffer. The distance vector may specify a maximum allowable distance between the buffer and a buffer that is currently fetched by the I/O device. Alternatively, a condition for the I/O device relinquishing ownership of a buffer may be provided by a timer. The timer may specify a maximum time that the I/O device may maintain ownership of a particular buffer. In other implementations, a mechanism is provided to force the I/O device to relinquish some or all of the buffers that it controls.