Le mardi 14 février 2012 à 18:43 +0200, alekcejk@googlemail.com a
écrit :

В сообщении от Вторник 14 февраля 2012 17:00:10 вы написали:

quoted

Le mardi 14 février 2012 à 16:28 +0200, alekcejk@googlemail.com a

écrit :

quoted

Yes, results are the same for 3.2.3 kernel with and without running
this command and for geographically close to me server (speed not limited)
and for server not close to me speed limitation the same.

I wonder if "netstat -s" is telling the truth ...

Could you post after a transfert on 3.2, "grep TcpExt /proc/net/netstat"

Kernel 3.2.6 (2.6.42.6-3.fc15.i686):

Before downloading:
TcpExt: SyncookiesSent SyncookiesRecv SyncookiesFailed EmbryonicRsts PruneCalled RcvPruned OfoPruned OutOfWindowIcmps LockDroppedIcmps ArpFilter TW TWRecycled TWKilled PAWSPassive 
PAWSActive PAWSEstab DelayedACKs DelayedACKLocked DelayedACKLost ListenOverflows ListenDrops TCPPrequeued TCPDirectCopyFromBacklog TCPDirectCopyFromPrequeue TCPPrequeueDropped 
TCPHPHits TCPHPHitsToUser TCPPureAcks TCPHPAcks TCPRenoRecovery TCPSackRecovery TCPSACKReneging TCPFACKReorder TCPSACKReorder TCPRenoReorder TCPTSReorder TCPFullUndo 
TCPPartialUndo TCPDSACKUndo TCPLossUndo TCPLoss TCPLostRetransmit TCPRenoFailures TCPSackFailures TCPLossFailures TCPFastRetrans TCPForwardRetrans TCPSlowStartRetrans TCPTimeouts 
TCPRenoRecoveryFail TCPSackRecoveryFail TCPSchedulerFailed TCPRcvCollapsed TCPDSACKOldSent TCPDSACKOfoSent TCPDSACKRecv TCPDSACKOfoRecv TCPAbortOnSyn TCPAbortOnData 
TCPAbortOnClose TCPAbortOnMemory TCPAbortOnTimeout TCPAbortOnLinger TCPAbortFailed TCPMemoryPressures TCPSACKDiscard TCPDSACKIgnoredOld TCPDSACKIgnoredNoUndo 
TCPSpuriousRTOs TCPMD5NotFound TCPMD5Unexpected TCPSackShifted TCPSackMerged TCPSackShiftFallback TCPBacklogDrop TCPMinTTLDrop TCPDeferAcceptDrop IPReversePathFilter 
TCPTimeWaitOverflow TCPReqQFullDoCookies TCPReqQFullDrop
TcpExt: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 47 0 0 0

After downloading FreeBSD-8.2-RELEASE-i386-dvd1.iso.xz with speed 5,8 Megabytes/s
TcpExt: SyncookiesSent SyncookiesRecv SyncookiesFailed EmbryonicRsts PruneCalled RcvPruned OfoPruned OutOfWindowIcmps LockDroppedIcmps ArpFilter TW TWRecycled TWKilled PAWSPassive 
PAWSActive PAWSEstab DelayedACKs DelayedACKLocked DelayedACKLost ListenOverflows ListenDrops TCPPrequeued TCPDirectCopyFromBacklog TCPDirectCopyFromPrequeue TCPPrequeueDropped 
TCPHPHits TCPHPHitsToUser TCPPureAcks TCPHPAcks TCPRenoRecovery TCPSackRecovery TCPSACKReneging TCPFACKReorder TCPSACKReorder TCPRenoReorder TCPTSReorder TCPFullUndo 
TCPPartialUndo TCPDSACKUndo TCPLossUndo TCPLoss TCPLostRetransmit TCPRenoFailures TCPSackFailures TCPLossFailures TCPFastRetrans TCPForwardRetrans TCPSlowStartRetrans TCPTimeouts 
TCPRenoRecoveryFail TCPSackRecoveryFail TCPSchedulerFailed TCPRcvCollapsed TCPDSACKOldSent TCPDSACKOfoSent TCPDSACKRecv TCPDSACKOfoRecv TCPAbortOnSyn TCPAbortOnData 
TCPAbortOnClose TCPAbortOnMemory TCPAbortOnTimeout TCPAbortOnLinger TCPAbortFailed TCPMemoryPressures TCPSACKDiscard TCPDSACKIgnoredOld TCPDSACKIgnoredNoUndo 
TCPSpuriousRTOs TCPMD5NotFound TCPMD5Unexpected TCPSackShifted TCPSackMerged TCPSackShiftFallback TCPBacklogDrop TCPMinTTLDrop TCPDeferAcceptDrop IPReversePathFilter 
TCPTimeWaitOverflow TCPReqQFullDoCookies TCPReqQFullDrop
TcpExt: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 11 0 0 0 0 0 2896 0 0 1426425 2 1 9 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 47 0 0 0

OK thanks, nothing seems wrong on receiver side.

Could you try to force ECN enabled flows and send tcpdump, to check if
we receive retransmits ?

echo 1 >/proc/sys/net/ipv4/tcp_ecn


And check tcp can engage ECN : tcpdump SYN/SYNACK should look like:

05:41:17.943538 IP 192.168.1.97.45986 > 68.232.35.119.80: Flags [SEW],
seq 2109565072, win 14600, options [mss 1460,sackOK,TS val 8295492 ecr
0,nop,wscale 6], length 0

05:41:17.980619 IP 68.232.35.119.80 > 192.168.1.97.45986: Flags [S.E],
seq 2519424885, ack 2109565073, win 14600, options [mss
1452,nop,nop,sackOK,nop,wscale 6], length 0

...