Subject: Re: UDP multicast packet loss not reported if TX ring overrun?

From: Nivedita Singhvi <[email-masked]>
Date: Mon, 17 Aug 2009 13:40:06 -0700

Christoph Lameter wrote:
> If I use a large send queue
> 
> (echo 2000000 >/proc/sys/net/core/wmem_default)
> 
> then lots of packet loss results if I try to send more packets than
> the bandwidth of the wire (300 bytes the maximum rate is 341k pps). With a
> size of 2M for the output buffer the TX ring is overrun.
> 
> But this loss is nowhere seen in any counter increments:

Is there any chance this is getting dropped at qdisc?
Can you check with tc?

thanks,
Nivedita