On (01/18/18 07:54), Eric Dumazet wrote: > > Some applications out there would break horribly, trust me. >
so I'm not particularly attached to that solution, and I appreciate the wisdom (and the NACK), but lets try to find a useful alternative The current zcopy completion notification mechanism involves syscall overhead already, and is also inadequate for threaded applications sharing an fd. Plus it wont work for datagram sockets. I'm fine with Willem's suggestion of passing a fixed number of cookies as ancillary data (with CTRUNC to denote inadequate buffer) but if we are really so thrifty about syscall overhead, we should not be using sk_error_queue in the first place- perhaps we can pass up the completion notification as ancillary data with recvmsg() on the POLLIN channel itself (which is weird if there is no data to recv, and only ancillary info to pass up, but hey, we are "performant"!). --Sowmini
