Virtual memory protocol segmentation offloading

A non-transitory program storage device readable by one or more processors of a network device, tangibly embodying a program of instructions executable by the one or more processors to perform method steps for performing transport layer protocol segmentation offloading, the method comprising:

• storing a plurality of buffer descriptors in a system memory of the network device, each of the plurality of buffer descriptors containing information indicative of a starting address of a payload buffer stored in a user memory space of the system memory, each of the plurality of payload buffers containing payload data originated by a user process running on a processor of the one or more processors;
• retrieving the payload data from the plurality of payload buffers without copying the payload data from the user memory space to a kernel memory space of the system memory by performing direct virtual memory addressing of the user memory space;
• and
• segmenting the payload data across one or more transport layer protocol packets.

A method comprising:

• storing a buffer descriptor in a system memory of a network device, the buffer descriptor containing information indicative of a starting address of a payload buffer in the system memory containing payload data originated by a user process running on a host processor of the network device;
• and
• an interface performing direct virtual memory addressing of a user memory space of the system memory on behalf of a network processor of the network device to fetch the payload data;
• and
• the network processor creating one or more Transmission Control Protocol (TCP) packets by performing TCP segmentation to segment the payload data across the one or more TCP packets.

A network device comprising:

• a processor configured to execute one or more kernel processes and one or more user processes;
• a system memory, coupled to the processor, having stored therein a page table data structure containing information for use in connection with translating virtual addresses to physical addresses, the system memory having a kernel memory space designated for use by the one or more kernel processes and a user memory space designated for use by the one or more user processes;
• a network interface operable to segment payload data across one or more network packets and to transmit the one or more network packets to a destination via a network;
• an interconnect bus coupled to the processor and the system memory;
• and
• an interface, coupled to the network interface and the interconnect bus, operable to:
• retrieve a buffer descriptor from the system memory, the buffer descriptor containing (i) a virtual memory address of corresponding payload data in the user memory space and (ii) a base address of a page directory of a page table data structure;
• and
• fetch the corresponding payload data from the user memory space on behalf of the network interface by performing direct virtual memory addressing of the system memory on behalf of the network interface based on the virtual memory address and the base address by using a directory entry of the page directory identified by the base address to translate the virtual memory address to a physical address within the user memory space.

A method comprising:

• without copying data from a user memory space to a kernel memory space of a system memory of a network device, making payload data originated by a user process running on a host processor of the network device available to a network processor of a network interface of the network device by storing a plurality of buffer descriptors to the system memory, each of the plurality of buffer descriptors containing information indicative of a starting address of a corresponding one of a plurality of payload buffers stored in the user memory space, wherein each of the plurality of payload buffers contains therein at least a portion of the payload data;
• retrieving, by a bus/memory interface of the network device on behalf of the network processor, the payload data from the plurality of payload buffers on behalf of a network processor of the network device by performing direct virtual memory addressing of the user memory space;
• and
• segmenting the payload data, by the network processor, across one or more transport layer protocol packets.