On 21 Nov 2014, at 15:20, Marko Zec <z...@fer.hr> wrote: >> Bjoern and I chatted for the last twenty or so minutes about the >> code, and believe that as things stand, it is *not* safe to turn off >> UMA_ZONE_NOFREE for TCP due to a teardown race in TCP that has been >> known about and discussed for several years, but is some work to >> resolve and that we've not yet found time to do so. The XXXRW's in >> tcp_timer.c are related to this. We're pondering ways to fix it but >> think this is not something that can be rushed. > > OK fair enough - thanks a lot for looking into this! > > Skimming through a bunch of hosts with moderately loaded hosts with > reasonably high uptime I couldn't find one where net.inet.tcp.timer_race > was not zero. A ny suggestions how to best reproduce the race(s) in > tcp_timer.c?
They would likely occur only on very highly loaded hosts, as they require race conditions to arise between TCP timers and TCP close. I think I did manage to reproduce it at one stage, and left the counter in to see if we could spot it in production, and I have had (multiple) reports of it in deployed systems. I'm not sure it's worth trying to reproduce them, given that knowledge -- we should simply fix them. Robert _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
