Re: poll(): IN/OUT vs {RD,WR}NORM
Johnny Billquist <[email protected]>
| Newsgroups | gmane.os.netbsd.devel.kernel |
|---|---|
| Message-ID | <[email protected]> |
On 2024-05-28 03:05, Greg Troxel wrote: > Johnny Billquist <[email protected]> writes: > >> POLLPRI High priority data may be read without blocking. >> >> POLLRDBAND Priority data may be read without blocking. >> >> POLLRDNORM Normal data may be read without blocking. > > Is this related to the "oob data" scheme in TCP (which is a hack that > doesn't work)? Where do we attach 3 priority levels to data? At the end of my quoting there were: The distinction between normal, priority, and high-priority data is specific to particular file types or devices. So in the context of poll itself, it's undefined. But it's easy to think that the TCP urgent data would be something usable in this context. But as you note, the urgent data is a somewhat broken thing that noone ever really figured out how it was meant to be used or anything about it at all. It's not really even oob. And it should basically just go away. But poll isn't really getting into any details about this. Just that if you have some sort of device of file, where you can assign multiple priorities to the data, then poll can make use of it. I have no idea if any such device or file ever have had such a distinction. Johnny -- Johnny Billquist || "I'm on a bus || on a psychedelic trip email: [email protected] || Reading murder books pdp is alive! || tryin' to stay hip" - B. Idol