> I believe you're misunderstanding the meaning of the timeout in select(2). > Timeout applies only when no FDs are ready.
The specific problem with bpf is that one might have a half-full buffer of captured data when the select timeout hits. In that case the select returns with no FDs ready while I think it really should return with the bpf fd. (and if you look at the code on sys/net/bpf.c, there is timeout handling towards that goal) but I´ve yet to figure out where it goes wrong. IMO, at timeout the code should check if bd_slen > 0 and if yes, do ROTATE_BUFFERS and bpf_wakeup() Unfortunately I´m not a kernel wizard enough to have fixed this, at least not yet. The functionality I´m looking for is to get all the packets accumulated, say in 1 second in single read regardless of if I got a buffer´s full of data. > > Also, you might be better off setting immediate mode on your bpf fd, > if you want a return before the buffer is full. > Immediate mode practically causes the reader to be waken up for every packet, ending up with huge number of small reads which is highly ineffective. Pete > On Mon, Nov 04, 2002 at 12:12:26AM +0200, Petri Helenius wrote: > > > > I believe the select operation on bpf is not functioning as supposed to. > > I?m calling select with 100ms timeout. The bpf interface is listening to > > an interface with constant packet rate, so it?s certain that multiple packets > > have been received during the select call. However the fd for the bpf > > device is not set until the bpf buffer is full. (which might be several seconds > > away since I?m using fairly large bpf buffers) > > > > Looking at the code I get the impression that if there are packets on the bpf > > buffer when the select timeouts, it should return the fd for the bpf ? > > > > Pete > > > > > > > > To Unsubscribe: send mail to [EMAIL PROTECTED] > > with "unsubscribe freebsd-net" in the body of the message > > -- > Barney Wolff http://www.databus.com/bwresume.pdf > I'm available by contract or FT, in the NYC metro area or via the 'Net. > To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-net" in the body of the message
