On Fri, Jun 22, 2018 at 05:28:50PM +0200, Christoph Hellwig wrote: > On Fri, Jun 22, 2018 at 04:14:09PM +0100, Al Viro wrote: > > > > > > http://git.infradead.org/users/hch/vfs.git/shortlog/refs/heads/remove-get-poll-head > > > > See objections upthread re "fs,net: move poll busy loop handling into a > > separate method"; as for the next one... I'd like an ACK from networking > > folks. The rest of queue makes sense. > > I want to see basic results first before micro-optimizing. After that > I'll send it out to the net folks for feedback.
I looked into this a bit, in the end sk_can_busy_loop does this: return sk->sk_ll_usec && !signal_pending(current); where sk_ll_usec defaults based on a sysctl that needs to be turned on, but can be overriden per socket. While at the same time corect poll code already checks net_busy_loop_on to set POLL_BUSY_LOOP. So except for sockets where people set the timeout to 0 the code already does the right thing as-is. IMHO not really worth wasting a FMODE_* flag for it, but if you insist I'll add it.