On 07/11/2018 10:12 AM, Magnus Karlsson wrote: > This patch set adjusts the AF_XDP TX error reporting so that it becomes > consistent between copy mode and zero-copy. First some background: > > Copy-mode for TX uses the SKB path in which the action of sending the > packet is performed from process context using the sendmsg > syscall. Completions are usually done asynchronously from NAPI mode by > using a TX interrupt. In this mode, send errors can be returned back > through the syscall. > > In zero-copy mode both the sending of the packet and the completions > are done asynchronously from NAPI mode for performance reasons. In > this mode, the sendmsg syscall only makes sure that the TX NAPI loop > will be run that performs both the actions of sending and > completing. In this mode it is therefore not possible to return errors > through the sendmsg syscall as the sending is done from the NAPI > loop. Note that it is possible to implement a synchronous send with > our API, but in our benchmarks that made the TX performance drop by > nearly half due to synchronization requirements and cache line > bouncing. But for some netdevs this might be preferable so let us > leave it up to the implementation to decide. > > The problem is that the current code base returns some errors in > copy-mode that are not possible to return in zero-copy mode. This > patch set aligns them so that the two modes always return the same > error code. We achieve this by removing some of the errors returned by > sendmsg in copy-mode (and in one case adding an error message for > zero-copy mode) and offering alternative error detection methods that > are consistent between the two modes.
Looks good, applied to bpf, thanks Magnus!
