Dustin Spicuzza wrote: > Hey, > > I've been trying to determine the performance of my application (ie, > when does it start dropping packets). I am using the current version of > libpcap in git, with Ubuntu 9.04 server (kernel 2.6.28-15-server). I am > using the new pcap API calls to set the ring buffer to something like > 2GB, and I'm reasonably sure that pcap compiles with mmap support enabled. > > I noticed that when looking at the packet counts as reported by > ifconfig, it agrees with the counts reported by my generator box, and in > this particular instance it reports a handful of dropped packets. > However, the number of packets my application processed is the number > reported by ifconfig, but pcap_get_stats() does *not* report the number > of dropped packets correctly. > > > Traffic generator ifconfig: > > 41843935 inbound, 0 drops > 27987584 outbound, 0 drops > > Application box ifconfig: > > 41843935 inbound, 1382 drops > 27987584 outbound, 0 drops > > Application report via pcap_get_stats() > > 41842553 inbound, 0 drops > 27987584 outbound, 0 drops > > Any thoughts on why this might be the case, and where I can find the bug? > > Dustin
So after reading the libpcap and kernel source, I see that this is actually how its supposed to work. But it *seems* like it would be quite nice if we could grab the interface driver drop statistics as well as drops resulting from the capture buffer filling up. I'm looking for a way to query the kernel about this number -- should I bother submitting a patch if I can get it, or is the current behavior more desired? Dustin -- Innovation is just a problem away
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