Date: Sun, 23 Mar 2003 18:07:21 +0100 From: Borje Josefsson <bj@dc.luth.se> To: freebsd-net@freebsd.org Subject: Does net.inet.tcp.inflight_enable work as expected? Message-ID: <200303231707.h2NH7LKl021437@dc.luth.se>
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Hello,
I have been playing around with the TCP parameters to try to tune my
system for high BW long distance transfer.
Sending host with -CURRENT (as of yesterday) GigE card (bge) and the
following parameters set:
kern.ipc.maxsockbuf: 8388608
net.inet.tcp.sendspace: 3230781
net.inet.tcp.recvspace: 3230781
net.inet.tcp.rfc1323: 1
net.inet.tcp.inflight_enable: 0
net.inet.tcp.inflight_min: 16000
net.inet.tcp.slowstart_flightsize: 8
kern.ipc.nmbclusters: 9024
This gives (with ttcp) between a pair of hosts 80 km (50 miles) apart -
with a RTT of 1.6 ms:
root@stinky 33# ttcp -s -t -f m -l 61440 -n 20345 dino
ttcp-t: buflen=61440, nbuf=20345, align=16384/0, port=5001 tcp -> dino
ttcp-t: socket
ttcp-t: connect
ttcp-t: 1249996800 bytes in 27.26 real seconds = 349.86 Mbit/sec +++
ttcp-t: 20345 I/O calls, msec/call = 1.37, calls/sec = 746.37
ttcp-t: 0.0user 15.9sys 0:27real 58% 15i+354d 416maxrss 0+0pf 0+45863csw
During that time "netstat 1" shows:
input (Total) output
packets errs bytes packets errs bytes colls
14888 0 982608 26946 0 40793188 0
14956 0 987096 27116 0 41049856 0
14857 0 980562 26902 0 40728292 0
15025 0 991650 27201 0 41178314 0
14808 0 977328 26818 0 40601116 0
15100 0 996600 27327 0 41370238 0
14801 0 976866 26818 0 40600244 0
14877 0 981882 26903 0 40728982 0
14934 0 985644 26945 0 40792362 0
14985 0 989010 26947 0 40792598 0
14924 0 984984 26904 0 40729392 0
15033 0 992178 27032 0 40921424 0
--------------------> Then I do this:
root@stinky 34# sysctl net.inet.tcp.inflight_enable=1
net.inet.tcp.inflight_enable: 0 -> 1
And get:
root@stinky 35# ttcp -s -t -f m -l 61440 -n 20345 dino
ttcp-t: buflen=61440, nbuf=20345, align=16384/0, port=5001 tcp -> dino
ttcp-t: socket
ttcp-t: connect
ttcp-t: 1249996800 bytes in 458.75 real seconds = 20.79 Mbit/sec +++
ttcp-t: 20345 I/O calls, msec/call = 23.09, calls/sec = 44.35
ttcp-t: 0.1user 408.5sys 7:38real 89% 15i+353d 416maxrss 0+0pf
62662+100667csw
During that time "netstat 1" shows:
input (Total) output
packets errs bytes packets errs bytes colls
1095 0 72270 2106 0 3185530 0
1093 0 72138 2123 0 3212886 0
978 0 64548 1919 0 2902774 0
946 0 62436 1857 0 2810162 0
1040 0 68640 2044 0 3092024 0
879 0 58014 1740 0 2633024 0
1008 0 66528 1994 0 3016324 0
937 0 61842 1867 0 2825302 0
1034 0 68244 2043 0 3090510 0
963 0 63558 1911 0 2891918 0
941 0 62106 1865 0 2821754 0
991 0 65406 1911 0 2891918 0
1007 0 66462 1910 0 2889132 0
1048 0 69168 1994 0 3017580 0
1062 0 70092 2041 0 3087466 0
998 0 65868 1912 0 2893432 0
1091 0 72006 2120 0 3207072 0
962 0 63492 1871 0 2831358 0
Either I have completely misunderstood the effect of inflight_enable, or
something is very wrong?!?
Any ideas?
--Börje
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