Messages in this thread | | | Subject | Re: TCP connection issues against Amazon S3 | From | Eric Dumazet <> | Date | Tue, 06 Jan 2015 08:04:13 -0800 |
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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
Could you post output of 'nstat' command ?
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