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sys_attrs_socket(5)					  sys_attrs_socket(5)



NAME

  sys_attrs_socket - socket subsystem attributes

DESCRIPTION

  This reference page lists and	describes attributes for the Socket (socket)
  kernel subsystem. Refer to the sys_attrs(5) reference	page for an introduc-
  tion to the topic of kernel subsystem	attributes.



  mbuf_ext_lock_count
      The number of lock entries to use	when taking a lock reference on	an
      external cluster mbuf (more is better).

      Default value: 64	(entries)

      Minimum value: 0

      Maximum value: 8192

      The mbuf_ext_lock_count attribute	is useful only on SMP machines where
      locks are	used.



  pftimerbindcpu
      The CPU number to	which to bind the protocol timer thread.

      Default value: 0

      Minimum value: 0

      Maximum value: UINT_MAX, or 4 billion



  sb_max
      Maximum size of the socket buffer.

      Default value: SB_MAX, or	1048576	(bytes)

      Minimum value: 1

      Maximum value: 4 billion



  sbcompress_threshold
      The maximum size of packets to be	copied into existing mbuf clusters,
      or compressed. Only packets of size less than sbcompress_threshold
      minus 1 are copied into existing mbuf clusters.

      Default value: 0 (bytes)

      Minimum value: 0

      Maximum value: UINT_MAX, or 4 billion

      If the sbcompress_threshold attribute value is 0,	mbuf cluster compres-
      sion is disabled.



  sobacklog_drops
      A	read-only attribute that is incremented	when a received	SYN packet is
      dropped because the number of queued SYN_RCVD connections	for a socket
      is equal to that socket's	backlog	limit. The initial value is 0.



  sobacklog_hiwat
      A	read-only attribute that shows the maximum number of pending requests
      to any of	the server sockets in the system. The initial value is 0.



  somaxconn
      Maximum number of	pending	TCP connections	(the socket listen queue
      limit).

      Default value: 1024 (connections)

      Minimum value: 0

      Maximum value: 65535

      If the listen queue connection limit is too small, incoming connect
      requests may be dropped. Pending TCP connections can be caused by	lost
      packets in the Internet or denial	of service attacks.



  somaxconn_drops
      A	read-only attribute that is  incremented when a	received SYN packet
      is dropped because the number of queued SYN_RCVD connections for a
      socket is	equal to the value of the somaxconn attribute. The initial
      value is 0.



  sominconn
      Minimum number of	pending	TCP connections	socket listen queue (back-
      log). The	attribute controls how many SYN	packets	can be handled simul-
      taneously	before additional requests are discarded.

      Default value: 0

      Minimum value: 0

      Maximum value: 65535

      The value	of the sominconn attribute overrides the application-specific
      backlog if the sominconn value is	greater	than the backlog requested by
      the application.



  umc A	value that enables (1) or disables (0)	socket writes without the
      need for a user space to kernel space copy operation. The	umc (unified
      mbuf cache) attribute is used in conjunction with	the mmap(2) system
      call.

      Default value: 0 (disabled)



  umc_min_len
      The size of the umc (unified mbuf	cache) buffer.

      Default value: 1024 (bytes)

      Minimum value: 0

      Maximum value: INT_MAX, or 2 billion

SEE ALSO

  sys_attrs(5)

  Tuning Tru64 UNIX for	Internet Servers at the	following location:
  http://www.tru64unix.compaq.com/faqs/publications/internet/TITLE.HTM.

  System Configuration and Tuning