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

On Mon, Jan 22, 2024 at 04:25:01PM +0100, Christian Brauner wrote:

On Sat, Jan 20, 2024 at 12:42:47AM +0000, Joe Damato wrote:

quoted

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 <redacted>
---

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.

OK, thanks for the review. An ioctl makes more sense, I agree.

I'll rewrite it as you've suggested and send another RFC.