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Date: Fri, 13 Apr 2007 18:41:11 +0200 From: Eric Dumazet <dada1@...mosbay.com> To: Daniel Schaffrath <danielschaffrath@....com> Cc: Ben Greear <greearb@...delatech.com>, Andi Kleen <andi@...stfloor.org>, netdev@...r.kernel.org, bcrl@...ck.org Subject: Re: TCP connection stops after high load. On Fri, 13 Apr 2007 18:10:12 +0200 Daniel Schaffrath <danielschaffrath@....com> wrote: > > On 2007/04/12 , at 20:19, Eric Dumazet wrote: > > > > Warning : tcpdump can lie, telling you packets being transmited > > several time. > Maybe you have further pointers how come that tcpdump lies about > duplicated packets? > dev_queue_xmit_nit() is called before attempting to send packet to device. If device could not accept the packet (hard_start_xmit() returns an error), packet is requeued and retried later. each retry means call ev_queue_xmit_nit() again, so tcpdump/sniffers can 'see' packet transmited several times. This is why I asked for "tc -s -d qdisc" results : to check the requeue counter (not its absolute value, but relative to number of packets sent) See dev_hard_start_xmit() in net/core/dev.c - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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