On 07/20/2009 09:56 AM, Hannes Reinecke wrote: > Hi all, > > we do have a problem with NOP processing. Under heavy I/O, the connection > starts spitting out > 'ping timeout' error messages and resetting the connection. > There has been _no_ error from the target side nor the connection, so it's > us, sadly. > > However, after some heavy instrumenting I found this: > [ 2664.456270] connection2:0: Sending nopout exp 1913193 max 1913177 queued > 1913194 > > [ 2664.462592] connection2:0: mgmtpdu [itt xa05 p ffff8100795675c0] queued > > [ 2584.459166] connection2:0: mgmtpdu [op 0x0 hdr->itt 0xa05 datalen 0] > > [ 2584.466259] connection2:0: mgmtpdu [itt 0xa05 p ffff8100795675c0] done > > [ 2585.232044] connection2:0: mgmtpdu [op 0x2 hdr->itt 0xa06 datalen 0] > > [ 2585.235410] connection2:0: mgmtpdu [itt 0xa06 p ffff810079567540] done > > [ 2666.376858] connection2:0: mgmtpdu [itt 0xa05 p ffff8100795675c0] > delayed, cmd 0 mgmt 0 req 0 exp 1913193 max 1913177 queued 1913194 > > [ 2667.169094] connection2:0: mgmtpdu [itt 0xa05 p ffff8100795675c0] > delayed, cmd 0 mgmt 0 req 0 exp 1913193 max 1913177 queued 1913194 > > [ 2667.179683] connection2:0: Sending nopout,cmd 0 mgmt 0 req 0 exp 1913193 > max 1913177 queued 1913194 > > [ 2669.092002] connection2:0: mgmtpdu [itt 0xa05 p ffff8100795675c0] > delayed, cmd 0 mgmt 0 req 0 exp 1913193 max 1913177 queued 1913194 > > [ 2669.093935] connection2:0: ping timeout of 5 secs expired, stat > 7880612636/308802796/2 state 1/-150303960 > > [ 2669.097568] connection2:0: iscsi: detected conn error (1011) > > [ 2669.201246] session2: blocking session > > [ 2669.206148] connection2:0: mgmtpdu [itt xa05 p ffff8100795675c0] finished > > > (ignore the clock skew, it's a multicore TSC problem ...). > > The numbers are ExpCmdSN, MaxCmdSN, and queued CmdSN. > So, as you can see, we're for some reason sending a NOP-Out with CmdSN > 1913194, ExpCmdSN 1913193, and MaxCmdSN 191377.
For queued CmdSn, are you printing out the session->queued_cmdsn or session->cmdsn? You probably want the session->cmdsn. The queued one is just internal. Actually you probably want to print out the hdr->cmdsn that is set in the prep functions, and you want to print it out the sn numbers right before the hdr is sent out in iscsi_xmit_task. If you are printing out the session->*cmdsn then we do this hdr->cmd_sn = session->cmdsn++; so after we send a hdr with the cmdsn we incremented the session tracking one and so the tracking one is going to be one higher than what we are actually sending. Where are you printing those values? You would want to print them from iscsi_data_xmit after they task has been prepd. > But reading through RFC 3720, I found this: > > The target MUST NOT transmit a MaxCmdSN that is less than > ExpCmdSN-1. For non-immediate commands, the CmdSN field can take any > value from ExpCmdSN to MaxCmdSN inclusive. The target MUST silently > ignore any non-immediate command outside of this range or non- > immediate duplicates within the range. The CmdSN carried by > immediate commands may lie outside the ExpCmdSN to MaxCmdSN range. > For example, if the initiator has previously sent a non-immediate > command carrying the CmdSN equal to MaxCmdSN, the target window is > closed. For group task management commands issued as immediate > commands, CmdSN indicates the scope of the group action (e.g., on > ABORT TASK SET indicates which commands are aborted). > > So no wonder we're never seeing any replies to that one. > > Question remains, though, why we're starting to send PDUs with invalid > MaxCmdSN numbers ... > Have you run in a wireshark trace to check if we are getting bad maxcmdsns from the target? libiscsi only copies it from the pdu, so maybe in iscsi_update_cmdsn() we are not copying MaxCmdSN when we should be or maybe the target is sending us bad values. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "open-iscsi" group. To post to this group, send email to firstname.lastname@example.org To unsubscribe from this group, send email to open-iscsi+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/open-iscsi -~----------~----~----~----~------~----~------~--~---