On (04/15/17 21:40), Andrew Lunn wrote: > > In my case, lan3 is up and idle, there are no packets flying around to > be captured. So i would expect pcap_next_ex() to exit once a second, > with a return value of 0. But it is not, it blocks and stays blocked. : > Looking at the libpcap source, the 1000ms timeout is being used as > part of the setsockopt(3, SOL_PACKET, PACKET_RX_RING, 0xbe9445c0, 28) > call, req.tp_retire_blk_tov is set to the timeoutval.
right, aiui, the retire_blk_tov will only kick in if we have at least one frame in a block, but the block is not filled up yet, before the req.tp_retire_blk_tov (1s in your case) expires. If there are 0 frames pending, we should not be waking up the app, so everything seems to be behaving as it should? --Sowmini
