Re: [RFC 1/1] eventpoll: support busy poll per epoll instance

[Christian Brauner]

On Sat, Jan 20, 2024 at 12:42:47AM +0000, Joe Damato wrote:
> Add F_EPOLL_{S,G}ET_BUSY_POLL_USECS to allow setting a busy poll timeout
> per epoll instance so that individual applications can enable (or
> disable) epoll based busy poll as needed.
> 
> Prior to this change, epoll-based busy poll could only be enabled
> system-wide, which limits the usefulness of busy poll.
> 
> Signed-off-by: Joe Damato <jdamato@xxxxxxxxxx>
> ---

This should be an ioctl on the epoll fd, not a fcntl(). fcntl()s
should aim to be generic which this isn't. We've recently rejected a
memfd addition as a fcntl() as well for the same reason.