kernel_optimize_test/Documentation/sysctl/net.txt
Linus Torvalds 496322bc91 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next
Pull networking updates from David Miller:
 "This is a re-do of the net-next pull request for the current merge
  window.  The only difference from the one I made the other day is that
  this has Eliezer's interface renames and the timeout handling changes
  made based upon your feedback, as well as a few bug fixes that have
  trickeled in.

  Highlights:

   1) Low latency device polling, eliminating the cost of interrupt
      handling and context switches.  Allows direct polling of a network
      device from socket operations, such as recvmsg() and poll().

      Currently ixgbe, mlx4, and bnx2x support this feature.

      Full high level description, performance numbers, and design in
      commit 0a4db187a9 ("Merge branch 'll_poll'")

      From Eliezer Tamir.

   2) With the routing cache removed, ip_check_mc_rcu() gets exercised
      more than ever before in the case where we have lots of multicast
      addresses.  Use a hash table instead of a simple linked list, from
      Eric Dumazet.

   3) Add driver for Atheros CQA98xx 802.11ac wireless devices, from
      Bartosz Markowski, Janusz Dziedzic, Kalle Valo, Marek Kwaczynski,
      Marek Puzyniak, Michal Kazior, and Sujith Manoharan.

   4) Support reporting the TUN device persist flag to userspace, from
      Pavel Emelyanov.

   5) Allow controlling network device VF link state using netlink, from
      Rony Efraim.

   6) Support GRE tunneling in openvswitch, from Pravin B Shelar.

   7) Adjust SOCK_MIN_RCVBUF and SOCK_MIN_SNDBUF for modern times, from
      Daniel Borkmann and Eric Dumazet.

   8) Allow controlling of TCP quickack behavior on a per-route basis,
      from Cong Wang.

   9) Several bug fixes and improvements to vxlan from Stephen
      Hemminger, Pravin B Shelar, and Mike Rapoport.  In particular,
      support receiving on multiple UDP ports.

  10) Major cleanups, particular in the area of debugging and cookie
      lifetime handline, to the SCTP protocol code.  From Daniel
      Borkmann.

  11) Allow packets to cross network namespaces when traversing tunnel
      devices.  From Nicolas Dichtel.

  12) Allow monitoring netlink traffic via AF_PACKET sockets, in a
      manner akin to how we monitor real network traffic via ptype_all.
      From Daniel Borkmann.

  13) Several bug fixes and improvements for the new alx device driver,
      from Johannes Berg.

  14) Fix scalability issues in the netem packet scheduler's time queue,
      by using an rbtree.  From Eric Dumazet.

  15) Several bug fixes in TCP loss recovery handling, from Yuchung
      Cheng.

  16) Add support for GSO segmentation of MPLS packets, from Simon
      Horman.

  17) Make network notifiers have a real data type for the opaque
      pointer that's passed into them.  Use this to properly handle
      network device flag changes in arp_netdev_event().  From Jiri
      Pirko and Timo Teräs.

  18) Convert several drivers over to module_pci_driver(), from Peter
      Huewe.

  19) tcp_fixup_rcvbuf() can loop 500 times over loopback, just use a
      O(1) calculation instead.  From Eric Dumazet.

  20) Support setting of explicit tunnel peer addresses in ipv6, just
      like ipv4.  From Nicolas Dichtel.

  21) Protect x86 BPF JIT against spraying attacks, from Eric Dumazet.

  22) Prevent a single high rate flow from overruning an individual cpu
      during RX packet processing via selective flow shedding.  From
      Willem de Bruijn.

  23) Don't use spinlocks in TCP md5 signing fast paths, from Eric
      Dumazet.

  24) Don't just drop GSO packets which are above the TBF scheduler's
      burst limit, chop them up so they are in-bounds instead.  Also
      from Eric Dumazet.

  25) VLAN offloads are missed when configured on top of a bridge, fix
      from Vlad Yasevich.

  26) Support IPV6 in ping sockets.  From Lorenzo Colitti.

  27) Receive flow steering targets should be updated at poll() time
      too, from David Majnemer.

  28) Fix several corner case regressions in PMTU/redirect handling due
      to the routing cache removal, from Timo Teräs.

  29) We have to be mindful of ipv4 mapped ipv6 sockets in
      upd_v6_push_pending_frames().  From Hannes Frederic Sowa.

  30) Fix L2TP sequence number handling bugs, from James Chapman."

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1214 commits)
  drivers/net: caif: fix wrong rtnl_is_locked() usage
  drivers/net: enic: release rtnl_lock on error-path
  vhost-net: fix use-after-free in vhost_net_flush
  net: mv643xx_eth: do not use port number as platform device id
  net: sctp: confirm route during forward progress
  virtio_net: fix race in RX VQ processing
  virtio: support unlocked queue poll
  net/cadence/macb: fix bug/typo in extracting gem_irq_read_clear bit
  Documentation: Fix references to defunct linux-net@vger.kernel.org
  net/fs: change busy poll time accounting
  net: rename low latency sockets functions to busy poll
  bridge: fix some kernel warning in multicast timer
  sfc: Fix memory leak when discarding scattered packets
  sit: fix tunnel update via netlink
  dt:net:stmmac: Add dt specific phy reset callback support.
  dt:net:stmmac: Add support to dwmac version 3.610 and 3.710
  dt:net:stmmac: Allocate platform data only if its NULL.
  net:stmmac: fix memleak in the open method
  ipv6: rt6_check_neigh should successfully verify neigh if no NUD information are available
  net: ipv6: fix wrong ping_v6_sendmsg return value
  ...
2013-07-09 18:24:39 -07:00

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Documentation for /proc/sys/net/*
(c) 1999 Terrehon Bowden <terrehon@pacbell.net>
Bodo Bauer <bb@ricochet.net>
(c) 2000 Jorge Nerin <comandante@zaralinux.com>
(c) 2009 Shen Feng <shen@cn.fujitsu.com>
For general info and legal blurb, please look in README.
==============================================================
This file contains the documentation for the sysctl files in
/proc/sys/net
The interface to the networking parts of the kernel is located in
/proc/sys/net. The following table shows all possible subdirectories. You may
see only some of them, depending on your kernel's configuration.
Table : Subdirectories in /proc/sys/net
..............................................................................
Directory Content Directory Content
core General parameter appletalk Appletalk protocol
unix Unix domain sockets netrom NET/ROM
802 E802 protocol ax25 AX25
ethernet Ethernet protocol rose X.25 PLP layer
ipv4 IP version 4 x25 X.25 protocol
ipx IPX token-ring IBM token ring
bridge Bridging decnet DEC net
ipv6 IP version 6 tipc TIPC
..............................................................................
1. /proc/sys/net/core - Network core options
-------------------------------------------------------
bpf_jit_enable
--------------
This enables Berkeley Packet Filter Just in Time compiler.
Currently supported on x86_64 architecture, bpf_jit provides a framework
to speed packet filtering, the one used by tcpdump/libpcap for example.
Values :
0 - disable the JIT (default value)
1 - enable the JIT
2 - enable the JIT and ask the compiler to emit traces on kernel log.
dev_weight
--------------
The maximum number of packets that kernel can handle on a NAPI interrupt,
it's a Per-CPU variable.
Default: 64
low_latency_read
----------------
Low latency busy poll timeout for socket reads. (needs CONFIG_NET_LL_RX_POLL)
Approximate time in us to busy loop waiting for packets on the device queue.
This sets the default value of the SO_LL socket option.
Can be set or overridden per socket by setting socket option SO_LL, which is
the preferred method of enabling.
If you need to enable the feature globally via sysctl, a value of 50 is recommended.
Will increase power usage.
Default: 0 (off)
low_latency_poll
----------------
Low latency busy poll timeout for poll and select. (needs CONFIG_NET_LL_RX_POLL)
Approximate time in us to busy loop waiting for events.
Recommended value depends on the number of sockets you poll on.
For several sockets 50, for several hundreds 100.
For more than that you probably want to use epoll.
Note that only sockets with SO_LL set will be busy polled, so you want to either
selectively set SO_LL on those sockets or set sysctl.net.low_latency_read globally.
Will increase power usage.
Default: 0 (off)
rmem_default
------------
The default setting of the socket receive buffer in bytes.
rmem_max
--------
The maximum receive socket buffer size in bytes.
wmem_default
------------
The default setting (in bytes) of the socket send buffer.
wmem_max
--------
The maximum send socket buffer size in bytes.
message_burst and message_cost
------------------------------
These parameters are used to limit the warning messages written to the kernel
log from the networking code. They enforce a rate limit to make a
denial-of-service attack impossible. A higher message_cost factor, results in
fewer messages that will be written. Message_burst controls when messages will
be dropped. The default settings limit warning messages to one every five
seconds.
warnings
--------
This controls console messages from the networking stack that can occur because
of problems on the network like duplicate address or bad checksums. Normally,
this should be enabled, but if the problem persists the messages can be
disabled.
netdev_budget
-------------
Maximum number of packets taken from all interfaces in one polling cycle (NAPI
poll). In one polling cycle interfaces which are registered to polling are
probed in a round-robin manner.
netdev_max_backlog
------------------
Maximum number of packets, queued on the INPUT side, when the interface
receives packets faster than kernel can process them.
netdev_tstamp_prequeue
----------------------
If set to 0, RX packet timestamps can be sampled after RPS processing, when
the target CPU processes packets. It might give some delay on timestamps, but
permit to distribute the load on several cpus.
If set to 1 (default), timestamps are sampled as soon as possible, before
queueing.
optmem_max
----------
Maximum ancillary buffer size allowed per socket. Ancillary data is a sequence
of struct cmsghdr structures with appended data.
2. /proc/sys/net/unix - Parameters for Unix domain sockets
-------------------------------------------------------
There is only one file in this directory.
unix_dgram_qlen limits the max number of datagrams queued in Unix domain
socket's buffer. It will not take effect unless PF_UNIX flag is specified.
3. /proc/sys/net/ipv4 - IPV4 settings
-------------------------------------------------------
Please see: Documentation/networking/ip-sysctl.txt and ipvs-sysctl.txt for
descriptions of these entries.
4. Appletalk
-------------------------------------------------------
The /proc/sys/net/appletalk directory holds the Appletalk configuration data
when Appletalk is loaded. The configurable parameters are:
aarp-expiry-time
----------------
The amount of time we keep an ARP entry before expiring it. Used to age out
old hosts.
aarp-resolve-time
-----------------
The amount of time we will spend trying to resolve an Appletalk address.
aarp-retransmit-limit
---------------------
The number of times we will retransmit a query before giving up.
aarp-tick-time
--------------
Controls the rate at which expires are checked.
The directory /proc/net/appletalk holds the list of active Appletalk sockets
on a machine.
The fields indicate the DDP type, the local address (in network:node format)
the remote address, the size of the transmit pending queue, the size of the
received queue (bytes waiting for applications to read) the state and the uid
owning the socket.
/proc/net/atalk_iface lists all the interfaces configured for appletalk.It
shows the name of the interface, its Appletalk address, the network range on
that address (or network number for phase 1 networks), and the status of the
interface.
/proc/net/atalk_route lists each known network route. It lists the target
(network) that the route leads to, the router (may be directly connected), the
route flags, and the device the route is using.
5. IPX
-------------------------------------------------------
The IPX protocol has no tunable values in proc/sys/net.
The IPX protocol does, however, provide proc/net/ipx. This lists each IPX
socket giving the local and remote addresses in Novell format (that is
network:node:port). In accordance with the strange Novell tradition,
everything but the port is in hex. Not_Connected is displayed for sockets that
are not tied to a specific remote address. The Tx and Rx queue sizes indicate
the number of bytes pending for transmission and reception. The state
indicates the state the socket is in and the uid is the owning uid of the
socket.
The /proc/net/ipx_interface file lists all IPX interfaces. For each interface
it gives the network number, the node number, and indicates if the network is
the primary network. It also indicates which device it is bound to (or
Internal for internal networks) and the Frame Type if appropriate. Linux
supports 802.3, 802.2, 802.2 SNAP and DIX (Blue Book) ethernet framing for
IPX.
The /proc/net/ipx_route table holds a list of IPX routes. For each route it
gives the destination network, the router node (or Directly) and the network
address of the router (or Connected) for internal networks.
6. TIPC
-------------------------------------------------------
The TIPC protocol now has a tunable for the receive memory, similar to the
tcp_rmem - i.e. a vector of 3 INTEGERs: (min, default, max)
# cat /proc/sys/net/tipc/tipc_rmem
4252725 34021800 68043600
#
The max value is set to CONN_OVERLOAD_LIMIT, and the default and min values
are scaled (shifted) versions of that same value. Note that the min value
is not at this point in time used in any meaningful way, but the triplet is
preserved in order to be consistent with things like tcp_rmem.