TCP ESTABLISHED Connection Sockets

Onload User Guide (UG1586)

Document ID

UG1586

Release Date

2023-07-31

Revision

1.2 English

The following table shows typical output for a TCP ESTABLISHED connection socket.

Table 1. Stackdump Output: TCP Established Connection Socket
Sample Output	Description
`TCP`	TCP socket.
`7:1`	Stack:socket id.
`lcl=192.168.1.2:50773`	Local ip:port address.
`rmt=192.168.1.1:34875`	Remote ip:port address.
`ESTABLISHED`	Connection is ESTABLISHED.
`lock: 10000000 UNLOCKED`	Internal socket lock status, as a hexadecimal number, followed by status names including: `LOCKED` `CONTENDED`.
`rx_wake=0000b6f4(RQ)`	Internal sequence value that is incremented each time a receive queue is ‘woken’. `(RQ)` indicates that a wake has been requested.
`tx_wake=00000002`	Internal sequence value that is incremented each time a transmit queue is ‘woken’. `(RQ)` indicates that a wake has been requested.
`flags:`	Flags (if any), including: `WK_TX`, `WK_RX` `TCP_PP` `ORPH` `ACCEPTQ` `DEFERRED` `AVOID_INT` `O_ASYNC`, `O_NONBLOCK`, `O_NDELAY`, `O_APPEND`, `O_CLOEXEC` `CACHE`, `PASSIVE_CACHE`, `CACHE_NO_FD` `OS_BACKED` `NONB_UNSYNCED.`
`ul_poll:`	User-level `poll()`:
`301326900 spin cycles`	in spin cycles
`100000 usec`	in μs.
`uid=0`	User id that owns this socket.
`s_flags:`	Socket flags, including: `CORK` `SHUTRD`, `SHUTWR` `TCP_NODELAY` `ACK` `REUSE` `KALIVE` `BCAST` `OOBIN` `LINGER` `DONTROUTE` `FILTER` `BOUND`, `ABOUND`, `PBOUND` `SNDBUF`, `RCVBUF` `SW_FILTER_FULL` `TRANSPARENT` `SCALACTIVE`, `SCALPASSIVE` `MAC_FILTER` `REUSEPORT` `BOUND_ALIEN` `CONNECT_MUST_BIND` `PMTU_DO` `ALWAYS_DF` `IP_TTL` `DEFERRED_BIND` `V6ONLY` `NOMCAST`.
`rcvbuf=129940`	Socket receive buffer size.
`sndbuf=131072`	Socket send buffer size.
`bindtodev=-1(-1,0:0)`	Device to which the socket is bound, given as an interface, or -1 if unbound. This is followed by an (interface index, hardware port:vlan) tuple.
`ttl=64`	Initial TTL value.
`rcvtimeo_ms=0`	Timeout value (microseconds) before an error is generated for receive functions, as set by SO_RCVTIMEO.
`sndtimeo_ms=0`	Timeout value (microseconds) before an error is generated for send functions, as set by SO_SNDTIMEO.
`sigown=0`	The PID receiving signals from this socket.
`cmsg=`	Current message flags, including: `NO_MCAST_TX`.
`rx_errno=0`	Zero whilst data can still arrive, otherwise contains error code.
`tx_errno=0`	Zero if transmit can still happen, otherwise contains error code.
`so_error=0`	Current socket error, or zero if no error.
`os_sock=0`	0 if the socket is handled by Onload, 1 if the socket is handled by the OS and not by Onload.
`TX`	Socket is being used for transmit.
`epoll3: ready_list_id 0`	List of ready sockets from the epoll3 set.
`tcpflags: TSO WSCL SACK ESTAB PASSIVE`	TCP flags currently set for this socket, including: `TSO` `WSCL` `SACK` `ECN` `STRIPE` `SYNCOOKIE` ESTAB `NONBCON` `PASSIVE` `ARP_FAIL` `NO_TX_ADVANCE` `LOOP_DEFER` `NO_QUICKACK` `MEM_DROP` `FIN_RECV` `ACTIVE_WILD` `MSG_WARM` `LOOP_FAKE` `TOA` `TLP_TIMER` `TLP_SENT` `FIN_PENDING`.
`local_peer: -1`	The peer socket in a local loopback connection.
`snd:`	Send data:
`up=b554bb86`	Urgent Pointer: the sequence number of the byte following the 00B byte.
`una-nxt-max=b554bb86-b554bb87-b556b6a6`	Sequence numbers of: `una`: first unacknowledged byte `nxt`: next byte we expect to be acknowledged `max`: last byte in the current send window.
`enq=b554bb87`	Sequence number of last byte currently queued for transmit.
`snd:`	Further send data:
`send=0(0)`	Number of bytes (packets) held in the send buffer.
`send+pre=0`	Number of packets in the pre-send queue. A process can add data to this queue when it is prevented from sending the data immediately. The data will be sent when the current sending operation is complete.
`inflight=1(1)`	Number of bytes (packets) sent but not yet acknowledged.
`wnd=129824`	Advertised window size of the receiver, in bytes.
`unused=129823`	Number of unused (free) bytes in that window.
`snd:`	Further send data:
`cwnd=49733+0`	Congestion window size, in bytes.
`used=0`	Portion of the congestion window that is currently in use.
`ssthresh=65535`	Number of bytes that have to be sent before the process can exit slow start.
`bytes_acked=0`	Number of bytes acknowledged. This value is used to calculate the rate at which the congestion window is opened.
`Open`	Current congestion window status, one of: `Open` `RTO` `RTORecovery` `FastRecovery` `Cooling` `RTOCooling` `Notified`.
`snd:`	Further send data:
`timed_seq 0`	First byte of timed packet.
`timed_ts 3fa5511c`	Timestamp for timed packet.
`snd:`	Further send data:
`sndbuf_pkts=136`	Size of the send buffer (packets). Send buffer is calculated as bytes.
`Onloaded(Valid)`	Status of cached control plane information, one of: `Onloaded` = can reach the destination via an accelerated interface `NoMac` `NoRoute` `ViaOs` `Local` `MacFail` followed by its validity: `(Valid)`: information is up-to-date. Can send immediately using this information. `(Old)`: information might be out-of-date. On next send Onload will do a control plane lookup - this will add some latency.
`if=6`	Interface being used.
`mtu=1500`	MTU being used.
`intf_i=0`	Intf_i value.
`vlan=0`	VLAN being used.
`encap=4`	Types of encapsulation supported by the NIC, as a hexadecimal mask.
`snd:`	Further send data:
`limited`	Counts of transmission being stopped for the following reasons:
`rwnd=0`	- receive window size
`cwnd=0`	- congestion window size
`nagle=0`	- Nagle's algorithm
`more=0`	- more (CORK, MSG_MORE)
`app=412548`	- transmit queue being empty.
`rcv:`	Receiver data:
`nxt-max=0e9251fe-0e944d1d`	Next byte we expect to receive and last byte we expect to receive (because of window size).
`wnd adv=129823`	Receiver advertised window size.
`cur=0e944d92`	Byte currently being processed.
`FASTSTART FAST`	Possible flags: `FASTSTART`: is in faststart `FAST`: can use fast path.
`rcv:`	Further receiver data:
`isn=b8f5ec59`	Initial sequence number.
`up=b8f5ec58`	Urgent Pointer: the sequence number of the byte following the 00B byte.
`urg_data=0000`	Urgent data: byte and associated flags.
`q=recv1`	Queue in use: `rcv1` or `rcv2`.
`rcv:`	Further receiver data:
`bytes=13201600`	Total number of bytes received.
`tot_pkts=`	Total number of packets received.
`rob_pkts=0`	Number of packets in the reorder buffer. Bytes received out of sequence are put into a reorder buffer awaiting further bytes before reordering can occur.
`q_pkts=2+0`	Number of packets queued in (`recv1`+`recv2`).
`usr=0`	Number of bytes of received data available to the user.
`eff_mss=1448`	Effective maximum segment size.
`smss=1460`	Sender maximum segment size.
`amss=1460`	Advertised maximum segment size.
`used_bufs=2`	Number of transmit buffers used.
`wscl`	Window scaling:
`s=2`	Send window scaling.
`r=2`	Receive window scaling.
`srtt=01`	Smoothed round trip time (RTT), in milliseconds.
`rttvar=000`	Round trip time (RTT) variation, in milliseconds.
`rto=189`	Current RTO timeout value, in ticks. To convert ticks to milliseconds, multiply by `ci_ip_time_tick2ms`.
`zwins=0,0`	Zero windows for probes,acks: times when advertised window has gone to zero size.
`curr_retrans=0`	Current re-transmissions.
`total_retrans=0`	Total re-transmissions.
`dupacks=0`	Number of duplicate acks received.
`congrecover=0`	Next sequence number to send when loss detected.
`rtos=0`	Number of retrans timeouts.
`frecs=0`	Number of fast recoveries.
`seqerr=0,0`	Number of sequence errors.
`ooo_pkts=0`	Number of out of sequence packets.
`ooo=0`	Number of out of order events.
`tx:`	Transmit data:
`defer=0`	Number of packets where send is deferred to stack lock holder.
`nomac=0`	Number of packets sent via the OS using raw sockets when up to date ARP data is not available.
`warm=0`	Number of packets sent using MSG_WARM.
`warm_aborted=0`	Number of times a message warm send function was called, but not sent due to onload lock constraints.
`tmpl:`	Templated send data:
`send_fast=0`	Number of fast templated sends.
`send_slow=0`	Number of slow templated sends.
`active=0`	Number of active templated sends.
`timers:`	Currently active timers:
`rto(200ms[3fa586ca])`	Retransmit timeout timer.