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freebsd-dev/sys/netinet
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Peter Wemm c4a184bdc4 Change TCPTV_MIN to be independent of HZ. While it was documented to 
be in ticks "for algorithm stability" when originally committed, it turns
out that it has a significant impact in timing out connections.  When we
changed HZ from 100 to 1000, this had a big effect on reducing the time
before dropping connections.

To demonstrate, boot with kern.hz=100.  ssh to a box on local ethernet
and establish a reliable round-trip-time (ie: type a few commands).
Then unplug the ethernet and press a key.  Time how long it takes to
drop the connection.

The old behavior (with hz=100) caused the connection to typically drop
between 90 and 110 seconds of getting no response.

Now boot with kern.hz=1000 (default).  The same test causes the ssh session
to drop after just 9-10 seconds.  This is a big deal on a wifi connection.

With kern.hz=1000, change sysctl net.inet.tcp.rexmit_min from 3 to 30.
Note how it behaves the same as when HZ was 100.  Also, note that when
booting with hz=100, net.inet.tcp.rexmit_min *used* to be 30.

This commit changes TCPTV_MIN to be scaled with hz.  rexmit_min should
always be about 30.  If you set hz to Really Slow(TM), there is a safety
feature to prevent a value of 0 being used.

This may be revised in the future, but for the time being, it restores the
old, pre-hz=1000 behavior, which is significantly less annoying.

As a workaround, to avoid rebooting or rebuilding a kernel, you can run
"sysctl net.inet.tcp.rexmit_min=30" and add "net.inet.tcp.rexmit_min=30"
to /etc/sysctl.conf.  This is safe to run from 6.0 onwards.

Approved by:  re (rwatson)
Reviewed by:  andre, silby
2007-07-31 22:11:55 +00:00
..
libalias o Kill EOLWS while I'm here. 2007-04-30 20:26:11 +00:00
accf_data.c
accf_http.c
icmp6.h - Disabled responding to NI queries from a global address by default as 2007-05-17 21:20:24 +00:00
icmp_var.h Attempt to improve feature parity between UDPv4 and UDPv6 by merging 2007-07-19 22:34:25 +00:00
if_atm.c Add newline to debuging printf. 2005-08-26 15:27:18 +00:00
if_atm.h
if_ether.c Move universally to ANSI C function declarations, with relatively 2007-05-10 15:58:48 +00:00
if_ether.h Add CARP (Common Address Redundancy Protocol), which allows multiple 2005-02-22 13:04:05 +00:00
igmp_var.h Import rewrite of IPv4 socket multicast layer to support source-specific 2007-06-12 16:24:56 +00:00
igmp.c Improve style(9) conformance of igmp.c. 2006-12-04 00:41:48 +00:00
igmp.h Stub out imported IGMPv3 definitions which clash with those of 2007-06-15 18:59:10 +00:00
in_cksum.c Move universally to ANSI C function declarations, with relatively 2007-05-10 15:58:48 +00:00
in_gif.c Move universally to ANSI C function declarations, with relatively 2007-05-10 15:58:48 +00:00
in_gif.h
in_mcast.c Fix a regression in IPv4 multicast join path (IP_ADD_MEMBERSHIP). 2007-07-09 10:36:47 +00:00
in_pcb.c Commit the change from FAST_IPSEC to IPSEC. The FAST_IPSEC 2007-07-03 12:13:45 +00:00
in_pcb.h Commit IPv6 support for FAST_IPSEC to the tree. 2007-07-01 11:41:27 +00:00
in_proto.c Commit the change from FAST_IPSEC to IPSEC. The FAST_IPSEC 2007-07-03 12:13:45 +00:00
in_rmx.c Move universally to ANSI C function declarations, with relatively 2007-05-10 15:58:48 +00:00
in_systm.h
in_var.h Import rewrite of IPv4 socket multicast layer to support source-specific 2007-06-12 16:24:56 +00:00
in.c Simplification to quiet a gcc4.2 warning. Just by setting match.s_addr 2007-06-17 00:31:24 +00:00
in.h Import rewrite of IPv4 socket multicast layer to support source-specific 2007-06-12 16:24:56 +00:00
ip6.h move RFC3542 related definitions into ip6.h. 2005-07-20 10:30:52 +00:00
ip_carp.c Replace references to NET_CALLOUT_MPSAFE with CALLOUT_MPSAFE, and remove 2007-07-28 07:31:30 +00:00
ip_carp.h Make sure that carp_header is 36 bytes long 2006-12-01 18:37:41 +00:00
ip_divert.c Reduce network stack oddness: implement .pru_sockaddr and .pru_peeraddr 2007-05-11 10:20:51 +00:00
ip_divert.h
ip_dummynet.c Replace references to NET_CALLOUT_MPSAFE with CALLOUT_MPSAFE, and remove 2007-07-28 07:31:30 +00:00
ip_dummynet.h Replace incorrect local OFFSET_OF macro with the correct and generic 2007-06-17 00:33:34 +00:00
ip_ecn.c Move universally to ANSI C function declarations, with relatively 2007-05-10 15:58:48 +00:00
ip_ecn.h
ip_encap.c Move universally to ANSI C function declarations, with relatively 2007-05-10 15:58:48 +00:00
ip_encap.h
ip_fastfwd.c In IPv4 fast forwarding path, send ICMP unreachable messages for 2007-03-18 23:05:20 +00:00
ip_fw2.c Replace references to NET_CALLOUT_MPSAFE with CALLOUT_MPSAFE, and remove 2007-07-28 07:31:30 +00:00
ip_fw_pfil.c Summer of Code 2005: improve libalias - part 2 of 2 2006-12-29 21:59:17 +00:00
ip_fw.h Add support for filtering on Routing Header Type 0 and 2007-05-04 11:15:41 +00:00
ip_gre.c Fix the following bpf(4) race condition which can result in a panic: 2006-06-02 19:59:33 +00:00
ip_gre.h Fix stack corruptions on amd64. 2006-01-21 10:44:34 +00:00
ip_icmp.c Attempt to improve feature parity between UDPv4 and UDPv6 by merging 2007-07-19 22:34:25 +00:00
ip_icmp.h Pass icmp_error() the MTU argument directly instead of 2005-05-04 13:09:19 +00:00
ip_id.c Minor white space and style cleanups. 2007-05-11 11:05:30 +00:00
ip_input.c Commit the change from FAST_IPSEC to IPSEC. The FAST_IPSEC 2007-07-03 12:13:45 +00:00
ip_ipsec.c Commit the change from FAST_IPSEC to IPSEC. The FAST_IPSEC 2007-07-03 12:13:45 +00:00
ip_ipsec.h Move the IPSEC related code blocks to their own file to unclutter 2006-02-01 13:55:03 +00:00
ip_mroute.c Replace references to NET_CALLOUT_MPSAFE with CALLOUT_MPSAFE, and remove 2007-07-28 07:31:30 +00:00
ip_mroute.h Store the cached route in vifp in the normal send_packet() case. 2007-02-08 23:05:08 +00:00
ip_options.c Normalize style a bit: reduce pseudo-randomness of comment layout and 2007-05-11 10:48:30 +00:00
ip_options.h Normalize style a bit: reduce pseudo-randomness of comment layout and 2007-05-11 10:48:30 +00:00
ip_output.c Commit the change from FAST_IPSEC to IPSEC. The FAST_IPSEC 2007-07-03 12:13:45 +00:00
ip_var.h Import rewrite of IPv4 socket multicast layer to support source-specific 2007-06-12 16:24:56 +00:00
ip.h White space and style cleanup. 2007-05-11 11:00:48 +00:00
ipprotosw.h
pim_var.h Remove public declarations of variables that were forgotten when they were 2005-08-10 07:10:02 +00:00
pim.h
raw_ip.c Commit the change from FAST_IPSEC to IPSEC. The FAST_IPSEC 2007-07-03 12:13:45 +00:00
sctp_asconf.c - take out a needless panic under invariants for sctp_output.c 2007-07-24 20:06:02 +00:00
sctp_asconf.h - take out a needless panic under invariants for sctp_output.c 2007-07-24 20:06:02 +00:00
sctp_auth.c - Matthew's changes to get inlines out, plus a few of my own 2007-06-16 00:33:47 +00:00
sctp_auth.h - fix send_failed notification contents 2007-06-09 13:46:57 +00:00
sctp_bsd_addr.c - The packet log needs to copy all of the buffer not to the end. 2007-06-17 23:43:37 +00:00
sctp_bsd_addr.h - Fixes so we won't try to start a timer when we 2007-05-29 09:29:03 +00:00
sctp_cc_functions.c - added pre-checks to the bindx call. 2007-07-17 20:58:26 +00:00
sctp_cc_functions.h - Modular congestion control, with RFC2581 being the default. 2007-07-14 09:36:28 +00:00
sctp_constants.h - added pre-checks to the bindx call. 2007-07-17 20:58:26 +00:00
sctp_crc32.c - Copyright change, cisco's silly tool wants it to say: 2007-05-08 17:01:12 +00:00
sctp_crc32.h - Copyright change, cisco's silly tool wants it to say: 2007-05-08 17:01:12 +00:00
sctp_header.h - Restructure so bindx functions are not done inline to socket option 2007-06-12 11:21:00 +00:00
sctp_indata.c - remove duplicate code from sctp_asconf.c 2007-07-21 21:41:32 +00:00
sctp_indata.h - Fix stream reset so it limits the number of streams that can be listed 2007-06-22 13:50:56 +00:00
sctp_input.c - take out a needless panic under invariants for sctp_output.c 2007-07-24 20:06:02 +00:00
sctp_input.h - Consolidate the code that free's chunks to actually also 2007-07-02 19:22:22 +00:00
sctp_lock_bsd.h - Fix so ifn's are properly deleted when the ref count goes to 0. 2007-06-14 22:59:04 +00:00
sctp_os_bsd.h - remove duplicate code from sctp_asconf.c 2007-07-21 21:41:32 +00:00
sctp_os.h - Modular congestion control, with RFC2581 being the default. 2007-07-14 09:36:28 +00:00
sctp_output.c - take out a needless panic under invariants for sctp_output.c 2007-07-24 20:06:02 +00:00
sctp_output.h - Take out the broken table-id concept. Panda Routers have a M-VRF 2007-06-01 11:19:54 +00:00
sctp_pcb.c - take out a needless panic under invariants for sctp_output.c 2007-07-24 20:06:02 +00:00
sctp_pcb.h - take out a needless panic under invariants for sctp_output.c 2007-07-24 20:06:02 +00:00
sctp_peeloff.c - added pre-checks to the bindx call. 2007-07-17 20:58:26 +00:00
sctp_peeloff.h - Copyright change, cisco's silly tool wants it to say: 2007-05-08 17:01:12 +00:00
sctp_structs.h - take out a needless panic under invariants for sctp_output.c 2007-07-24 20:06:02 +00:00
sctp_sysctl.c - Modular congestion control, with RFC2581 being the default. 2007-07-14 09:36:28 +00:00
sctp_sysctl.h - Modular congestion control, with RFC2581 being the default. 2007-07-14 09:36:28 +00:00
sctp_timer.c - take out a needless panic under invariants for sctp_output.c 2007-07-24 20:06:02 +00:00
sctp_timer.h - Modular congestion control, with RFC2581 being the default. 2007-07-14 09:36:28 +00:00
sctp_uio.h - Fix stream reset so it limits the number of streams that can be listed 2007-06-22 13:50:56 +00:00
sctp_usrreq.c - take out a needless panic under invariants for sctp_output.c 2007-07-24 20:06:02 +00:00
sctp_var.h - added pre-checks to the bindx call. 2007-07-17 20:58:26 +00:00
sctp.h - added pre-checks to the bindx call. 2007-07-17 20:58:26 +00:00
sctputil.c - take out a needless panic under invariants for sctp_output.c 2007-07-24 20:06:02 +00:00
sctputil.h - take out a needless panic under invariants for sctp_output.c 2007-07-24 20:06:02 +00:00
tcp_debug.c Rather than selectively zeroing fields in the tcp_debug structure 2007-05-07 14:05:23 +00:00
tcp_debug.h o Use a define for a buffer size. 2007-03-24 22:15:02 +00:00
tcp_fsm.h Make tcpstates[] static, and make sure TCPSTATES is defined before 2007-07-30 11:06:42 +00:00
tcp_hostcache.c Replace a constant with an already defined symbolic name for it. 2007-06-08 13:43:28 +00:00
tcp_input.c Make tcpstates[] static, and make sure TCPSTATES is defined before 2007-07-30 11:06:42 +00:00
tcp_output.c Commit the change from FAST_IPSEC to IPSEC. The FAST_IPSEC 2007-07-03 12:13:45 +00:00
tcp_reass.c Complete the (mechanical) move of the TCP reassembly and timewait 2007-05-13 22:16:13 +00:00
tcp_sack.c Coalesce two identical UCB licenses into a single license instance with 2007-05-11 11:21:43 +00:00
tcp_seq.h Remove T/TCP RFC1644 Connection Count comparison macros. They are no longer 2006-06-18 14:24:12 +00:00
tcp_subr.c Change TCPTV_MIN to be independent of HZ. While it was documented to 2007-07-31 22:11:55 +00:00
tcp_syncache.c Fix a typo in a log message: s/Reveived/Received/. 2007-07-29 20:13:22 +00:00
tcp_syncache.h Export the contents of the syncache to netstat. 2007-07-27 00:57:06 +00:00
tcp_timer.c Handle a race condition on >2 core machines in tcp_timer() when 2007-06-09 17:49:39 +00:00
tcp_timer.h Change TCPTV_MIN to be independent of HZ. While it was documented to 2007-07-31 22:11:55 +00:00
tcp_timewait.c Despite several examples in the kernel, the third argument of 2007-06-04 18:25:08 +00:00
tcp_usrreq.c Make tcpstates[] static, and make sure TCPSTATES is defined before 2007-07-30 11:06:42 +00:00
tcp_var.h Provide a sysctl to toggle reporting of TCP debug logging: 2007-07-28 12:20:39 +00:00
tcp.h The printf %b list in PRINT_TH_FLAGS has to be in octal numbering. 2007-05-25 21:28:49 +00:00
tcpip.h
udp_usrreq.c Further cleanup of UDPv4: 2007-07-10 09:30:46 +00:00
udp_var.h Further cleanup of UDPv4: 2007-07-10 09:30:46 +00:00
udp.h Gratuitous UDP restyling toward style(9) in 7.x. 2007-02-20 10:13:11 +00:00