> On 06 Jan 2015, at 16:04, Eric Dumazet <eric.duma...@gmail.com> wrote: > On Tue, 2015-01-06 at 15:14 +0000, Erik Grinaker wrote: >> (CCing Yuchung, as his name comes up in the relevant commits) >> >> After upgrading from Ubuntu 12.04.5 to 14.04.1 we have begun seeing >> intermittent TCP connection hangs for HTTP image requests against >> Amazon S3. 3-5% of requests will suddenly stall in the middle of the >> transfer before timing out. We see this problem across a range of >> servers, in several data centres and networks, all located in Norway. >> >> A packet dump [1] shows repeated ACK retransmits for some of the >> requests. Using Ubuntu mainline kernels, we found the problem to have >> been introduced between 3.11.10 and 3.12.0, possibly in >> 0f7cc9a3c2bd89b15720dbf358e9b9e62af27126. The problem is also present >> in 3.18.1. Disabling tcp_window_scaling seems to solve it, but has >> obvious drawbacks for transfer speeds. Other sysctls do not seem to >> affect it. >> >> I am not sure if this is fundamentally a kernel bug or a network >> issue, but we did not see this problem with older kernels. >> >> [1] http://abstrakt.bengler.no/tcp-issues-s3.pcap.bz2 > > > CC netdev > > This looks like the bug we fixed here : > > http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=39bb5e62867de82b269b07df900165029b928359
Has that patch gone into a release? Because the problem persists with 3.18.1. > Could you post output of 'nstat' command ? Sure: #kernel IpInReceives 1676194 0.0 IpInDelivers 1676115 0.0 IpOutRequests 1163105 0.0 IcmpInErrors 826 0.0 IcmpInEchoReps 826 0.0 IcmpOutErrors 824 0.0 IcmpOutTimeExcds 10 0.0 IcmpOutTimestamps 814 0.0 IcmpMsgInType8 826 0.0 IcmpMsgOutType0 814 0.0 IcmpMsgOutType3 10 0.0 TcpActiveOpens 2004 0.0 TcpPassiveOpens 1102 0.0 TcpAttemptFails 5 0.0 TcpEstabResets 34 0.0 TcpInSegs 1667699 0.0 TcpOutSegs 1159990 0.0 TcpRetransSegs 26 0.0 TcpOutRsts 504 0.0 UdpInDatagrams 2002 0.0 UdpOutDatagrams 2087 0.0 Ip6InReceives 1 0.0 Ip6InNoRoutes 1 0.0 Ip6OutRequests 10 0.0 Ip6OutDiscards 3 0.0 Ip6OutNoRoutes 1 0.0 Ip6OutMcastPkts 7 0.0 Ip6InOctets 76 0.0 Ip6OutOctets 728 0.0 Ip6OutMcastOctets 520 0.0 Ip6InNoECTPkts 1 0.0 Icmp6OutMsgs 4 0.0 Icmp6OutNeighborSolicits 1 0.0 Icmp6OutMLDv2Reports 3 0.0 Icmp6OutType135 1 0.0 Icmp6OutType143 3 0.0 TcpExtEmbryonicRsts 5 0.0 TcpExtPruneCalled 1 0.0 TcpExtTW 1897 0.0 TcpExtDelayedACKs 3058 0.0 TcpExtDelayedACKLocked 13 0.0 TcpExtDelayedACKLost 2330 0.0 TcpExtTCPPrequeued 3084 0.0 TcpExtTCPDirectCopyFromPrequeue 10944 0.0 TcpExtTCPHPHits 1246417 0.0 TcpExtTCPPureAcks 7512 0.0 TcpExtTCPHPAcks 3219 0.0 TcpExtTCPSackRecovery 2 0.0 TcpExtTCPLossUndo 4 0.0 TcpExtTCPFastRetrans 2 0.0 TcpExtTCPTimeouts 18 0.0 TcpExtTCPLossProbes 145 0.0 TcpExtTCPLossProbeRecovery 125 0.0 TcpExtTCPSackRecoveryFail 1 0.0 TcpExtTCPRcvCollapsed 22 0.0 TcpExtTCPDSACKOldSent 43 0.0 TcpExtTCPDSACKRecv 3 0.0 TcpExtTCPAbortOnData 113 0.0 TcpExtTCPDSACKIgnoredNoUndo 3 0.0 TcpExtTCPSpuriousRTOs 2 0.0 TcpExtTCPSackShiftFallback 3 0.0 TcpExtTCPRcvCoalesce 927994 0.0 TcpExtTCPOFOQueue 300911 0.0 TcpExtTCPOFOMerge 76 0.0 TcpExtTCPSpuriousRtxHostQueues 24 0.0 IpExtInBcastPkts 5588 0.0 IpExtInOctets 2454079082 0.0 IpExtOutOctets 56232776 0.0 IpExtInBcastOctets 3218688 0.0 IpExtInNoECTPkts 1676194 0.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
