On Sat, Aug 20, 2022, 7:35 AM Jin-oh Kang jinoh.kang.kr@gmail.com wrote:
Granted, if the fragmentation becomes too fine-grained (e.g. MSS or window size drops below the sk_buff overhead), the bookkeeping overhead prevails and the send() call may actually block. I'm not sure if this is actually possible, but even if this was the case, it's possible that the upstream Linux kernel would reject any fixes on the grounds that the application is expected to enable non-blocking mode when performing readiness-based I/O. Still, I'll try to raise this on LKML some time.
Independent of upstream fixes, would it be worth to merge this patch sooner? I'm concerned that there probably are far more apps that are broken other than just fb2k, especially since the poll-and-IO pattern is quite common.