Cisco Technology, Inc.

Satish Gannu

Saravanan Agasaveeran

Qingming Ma

John Gary Waclawsky

Steven Howard Berl

Aniruddha Khare

James Balestriere

Gordon Cox

M Salim Olime

Rajesh Agrawal

A method includes a step of (A) determining which of multiple network interfaces indicates readiness to transmit a data element to a network and which of the multiple network interfaces indicates receipt of a data element from the network. The method further includes a step of (B) running, for each network interface indicating readiness to transmit a data element to the network, a transmit interrupt handler to load that network interface with a data element for transmission if such a data element is available for transmission within the data communications device, in response to giving higher priority to handling transmit interrupts relative to handling receive interrupts. The method further includes a step of (C) after step B, running, for at least one network interface which indicates receipt of a data element from the network, a receive interrupt handler to process that data element.

Methods and apparatus for moving data elements within a data communications device

The invention is directed to techniques for moving data elements within a data communications device which prioritizes handling transmit interrupts over handling receive interrupts. Preferably, while attending to transmit interrupts, the device gives priority to the &ldquo;hungriest&rdquo; interfaces. In one arrangement, the device includes multiple network interfaces which are capable of transmitting and receiving data elements with a network, and a controller, coupled to the interfaces. The controller is configured to perform a method comprising the steps of: assigning weights to the interfaces based on interface transmission capacities and/or the number of data elements ready for transmission through the interfaces; determining which of the interfaces indicates readiness to transmit a data element to the network and which of the interfaces indicates receipt of a data element from the network; exclusively running, for each interface indicating readiness to transmit a data element to the network, a transmit interrupt handler to load that interface with a data element for transmission if such a data element is available for transmission within the data communications device (the handling order of the interfaces being determined by the weights so that the &ldquo;hungriest&rdquo; interfaces are handled first); and after the step of exclusively running transmit interrupt handlers, running, for at least one interface which indicates receipt of a data element from the network, a receive interrupt handler to process that data element and restricting the amount of time consumed running the receive interrupt handlers before handling transmit interrupts again. Since the device prioritizes handling transmit interrupts over receive interrupts in a weighted preferential manner, the device handles transmit interrupts as early as possible to move data elements quickly to the interfaces. Accordingly, it is less likely that interfaces will &ldquo;starve&rdquo; for data elements.

The invention is directed to techniques for transferring data using a device driver that is arranged to prevent improper operation of a non-primary routine (e.g., an administrative operation) from causing improper operation of a primary routine (e.g., a data transfer operation). Accordingly, the primary routine can continue to operate properly after a failure of the non-primary routine. In one arrangement, a data communications device transfers data. The data communications device includes a port that couples to a network, and a processor coupled to the port. The data communications device further includes memory, coupled to the processor, that stores a device driver. The device driver has a first set of instructions that directs the processor to perform a data transfer routine that moves data between memory and the port, and a second set of instructions that directs the processor to perform an administrative routine. The second set of instructions is arranged to prevent improper operation of the administrative routine from causing improper operation of the data transfer routine. In particular, execution and communication mechanisms enable the primary and administrative routines to operate in such a fault-tolerant manner.

Methods and apparatus for transferring data using a device driver

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Bengaluru, India

Satish Gannu