On Sat, 05 Aug 2006 03:28:38 -0400 Alan Shieh <ashieh@xxxxxxxxxxxxxx> wrote: > Hi everyone, > > I sometimes see packets stored out of order in pcap files that generated > by "tcpdump -i any" on kernel 2.4.26 with all packets arriving and > departing on an e1000 NIC. That is, the ordering by receive timestamp on > the packets is not the same as the ordering of the packets within the file. > > In my precise scenario, packets of RX packets show up in the log 230 ms > later than they ought to based on the receive timestamp. The kernel > behavior (e.g., the packets that are sent by this node) seems to reflect > the arrival of the Rx packet at the position in the logfile, rather than > the arrival time according to the timestamp. > > What are some of the known causes of this behavior? I'd like to know > what locks, etc. might be causing this processing / capture delay. SMP or single CPU? What is the clock source being used? If you had a CPU like dual-core AMD that doesn't sync TSC's and that was the clock source, the timestamps could be wrong. - : send the line "unsubscribe linux-net" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
