On (04/17/18 16:00), Willem de Bruijn wrote: > > This patchset implements GSO for UDP. A process can concatenate and > submit multiple datagrams to the same destination in one send call > by setting socket option SOL_UDP/UDP_SEGMENT with the segment size, > or passing an analogous cmsg at send time. > > The stack will send the entire large (up to network layer max size) > datagram through the protocol layer. At the GSO layer, it is broken > up in individual segments. All receive the same network layer header > and UDP src and dst port. All but the last segment have the same UDP > header, but the last may differ in length and checksum.
I'll go through the patch-set later today/tomorrow (interesting!), but a question: what are message boundary semantics in this model? E.g., if I do a udp_sendmsg of 2000 bytes, and then then a udp_sendmsg of 512 bytes, with the receiver first recvmsg 2000 bytes and then the 512 bytes? My understanding of the comment above is that no, it will not- because (assuming an mtu of 1500) there will be 2 UDP messages on the wire, the first one with 1500 bytes, and the second with 1012 bytes (with some discounts for the various L2/L3 etc headers) --Sowmini
