Messages in this thread |  | | Date | Sat, 06 Oct 2001 12:59:52 +0300 | From | Mika Liljeberg <> | Subject | Re: unnecessary retransmit from network stack |
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"David S. Miller" wrote: > > From: Christian Widmer <cwidmer@iiic.ethz.ch> > Date: Fri, 5 Oct 2001 14:29:53 +0200 > > why does net_dev.hard_start_xmit get called multiple times > with the same tcp packet? > > Because the ACK is not coming back for those packets within the RTO > (which for a local network is very low). Check your TCP dumps, > the ACKs of the original data packets are being dropped in transit.
Well, TCP certainly shouldn't be sending two retransmissions back-to-back within 2ms, especially with nothing received in between. Not with RTO (which in Linux is never below 20ms, and according to RFC should be conservatively rounded up to 1 second), nor with fast retransmits or SACK.
Just an observation.
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