Messages in this thread | | | Date | Wed, 02 Apr 2014 18:17:34 +0200 | From | Ortwin Glück <> | Subject | 3.14 regression: huge latency in read/select on tun |
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Hi,
Since 3.14 the openconnect VPN tunnel becomes unusable for me because packets appear on the tun device at a horribly low rate. 3.12 and 3.13 do not exhibt the problem.
Here is an strace of openconnect trying to read from its fd 7 -> /dev/net/tun
15:07:33.130640 read(7, 0x1e05e58, 1280) = -1 EAGAIN (Resource temporarily unavailable) ===> should return available data already 15:07:33.130745 select(8, [3 6 7], [], [6], {30, 0}) = 1 (in [7], left {29, 783272}) ===> HUGE 217ms delay here 15:07:33.347681 read(6, 0x1dfc973, 5) = -1 EAGAIN (Resource temporarily unavailable) 15:07:33.347806 read(7, "E\10\5\0b\343@\0@\6\17~\n\363X\236\n\271UE\222:\0\26\37O\7\342\315\21q\33"..., 1280) = 1280
The send queue of the socket being routed via the tun device has a lot of outstanding data (here an scp/ssh upload): tcp 0 29788 local:46577 remote:22 ESTABLISHED
(IPs replaced for privacy)
toggling TCP autocorking has no influence.
Any ideas what could be the culprit?
Ortwin
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