NDT-DEV email list created

Revision: 1090
Author:   

Date:     Wed Jun 18 07:17:31 2014 UTC
Log:      [No log message]
http://code.google.com/p/ndt/source/detail?r=1090

Added:
 /wiki/TCP_INFOvsWeb100Web10g.wiki

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--- /dev/null
+++ /wiki/TCP_INFOvsWeb100Web10g.wiki   Wed Jun 18 07:17:31 2014 UTC
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+#summary One-sentence summary of this page.
+
+= Introduction =
+Investigate the possible use of TCP_INFO instead of web100/web10g.
+
+
+= Details about TCP_INFO =
+==Structure of TCP_INFO:==
+{{{
+struct tcp_info
+{
+u_int8_t       tcpi_state;
+u_int8_t       tcpi_ca_state;
+u_int8_t       tcpi_retransmits;
+u_int8_t       tcpi_probes;
+u_int8_t       tcpi_backoff;
+u_int8_t       tcpi_options;
+u_int8_t       tcpi_snd_wscale : 4, tcpi_rcv_wscale : 4;
+
+u_int32_t      tcpi_rto;
+u_int32_t      tcpi_ato;
+u_int32_t      tcpi_snd_mss;
+u_int32_t      tcpi_rcv_mss;
+
+u_int32_t      tcpi_unacked;
+u_int32_t      tcpi_sacked;
+u_int32_t      tcpi_lost;
+u_int32_t      tcpi_retrans;
+u_int32_t      tcpi_fackets;
+
+/* Times. */
+u_int32_t      tcpi_last_data_sent;
+u_int32_t      tcpi_last_ack_sent;     /* Not remembered, sorry.  */
+u_int32_t      tcpi_last_data_recv;
+u_int32_t      tcpi_last_ack_recv;
+
+/* Metrics. */
+u_int32_t      tcpi_pmtu;
+u_int32_t      tcpi_rcv_ssthresh;
+u_int32_t      tcpi_rtt;
+u_int32_t      tcpi_rttvar;
+u_int32_t      tcpi_snd_ssthresh;
+u_int32_t      tcpi_snd_cwnd;
+u_int32_t      tcpi_advmss;
+u_int32_t      tcpi_reordering;
+};
+}}}
+You can find this structure in:
+{{{
+/usr/include/netinet/tcp.h
+}}}
+
+==Description of variables:==
+{{{
+tcpi_state;    /* Possible value:
+               TCP_ESTABLISHED = 1,
+               TCP_SYN_SENT,
+               TCP_SYN_RECV,
+               TCP_FIN_WAIT1,
+               TCP_FIN_WAIT2,
+               TCP_TIME_WAIT,
+               TCP_CLOSE,
+               TCP_CLOSE_WAIT,
+               TCP_LAST_ACK,
+               TCP_LISTEN,
+               TCP_CLOSING */
+
+tcpi_ca_state; /* Congestion control state */
+tcpi_retransmits;      /* Number of unrecovered [RTO] timeouts */
+tcpi_probes;   /* Unanswered 0 window probes */
+tcpi_backoff;  /* Backoff */
+tcpi_options;
+tcpi_snd_wscale        /* Window scaling received from sender */
+tcpi_rcv_wscale        /*Window scaling to send to receiver*/
+tcpi_rto;      /* Retransmit timeout */
+tcpi_ato;      /* Predicted tick of soft clock */
+tcpi_snd_mss;  /* Cached effective mss, not including SACKS*/
+tcpi_rcv_mss;  /* MSS used for delayed ACK decisions */
+
+tcpi_unacked;  /* Packets which are "in flight" */
+tcpi_sacked;   /* SACK'd packets */
+tcpi_lost;     /* Lost packets */
+tcpi_retrans;  /* Retransmitted packets out */
+tcpi_fackets;  /* FACK'd packets */
+
+tcpi_last_data_sent;	/* now – lsndtime (lsndtime → timestamp of last sent  
data packet (for restart window)) */
+tcpi_last_ack_sent;    /* Not remembered, sorry.  */
+tcpi_last_data_recv;	/* now – isck_ack.lrcvtime (isck_ack ->Delayed ACK  
control data; lrcvtime → timestamp of last received data packet) */
+tcpi_last_ack_recv;	/* now - rcv_tstamp  (rcv_tstamp → timestamp of last  
received ACK (for keepalives)) */
+
+tcpi_pmtu;     /* Last pmtu seen by socket (Path Maximum Transmission Unit) 
*/
+tcpi_rcv_ssthresh;	/* slow start size threshold for  receiving (Current  
window clamp) */
+tcpi_rtt;      /* Smoothed Round Trip Time (SRTT) */
+tcpi_rttvar;   /* Medium deviation */
+tcpi_snd_ssthresh;     /* Slow start size threshold for sending */
+tcpi_snd_cwnd; /* Sending congestion window */
+tcpi_advmss;   /* Advertised Maximum Segment Size (MSS) */
+tcpi_reordering;	/* Indicates the amount of reordering. Packet reordering  
metric */
+
+tcpi_rcv_rtt;  /* Receiver side RTT estimation */
+tcpi_rcv_space;        /* Receiver queue space */
+
+tcpi_total_retrans;    /* Total retransmits for entire connection */
+}}}
+
+==Useful information about the TCP_INFO:==
+TCP_INFO structure is filled in the tcp_get_info() function.You can find  
it in kernel source:
+{{{
+/lib/modules/`uname -r`/build/net/ipv4/tcp.c
+}}}
+Most of the data is copied from tcp_sock and inet_connection_sock  
structure.<br>
+tcp_sock struct you can find in:
+{{{
+/lib/modules/`uname -r`/build/include/linux/tcp.h
+or
+/lib/modules/`uname -r`/build/include/net/tcp.h
+}}}
+inet_connection_sock structure is in:
+{{{
+/lib/modules/`uname -r`/build/include/net/inet_connection_sock.h
+}}}
+
+= Comparison with Web100/Web10g =
+