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Date: Mon, 05 Oct 2009 10:56:44 -0700
From: Julian Elischer <julian@elischer.org>
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To: rihad <rihad@mail.ru>
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Cc: Eugene Grosbein <eugen@kuzbass.ru>, Luigi Rizzo <rizzo@iet.unipi.it>,
	freebsd-net@freebsd.org
Subject: Re: dummynet dropping too many packets
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rihad wrote:
> Julian Elischer wrote:
>> Luigi Rizzo wrote:
>>
>>>> Taildrop does not really help with this. GRED does much better.
>>>
>>> i think the first problem here is figure out _why_ we have
>>> the drops, as the original poster said that queues are configured
>>> with a very large amount of buffer (and i think there is a
>>> misconfiguration somewhere because the mbuf stats do not make
>>> sense)
>>
>> it all depends on the characteristics of the traffic
>>
>> you need different queue lengths if it is just a small number of high 
>> speeed sessions (and mayne a large number of slow speed sessions),
>> or if it is a larger number of medium speed sessions.
>>
>> Is it possible to know what sessions are losing packets?
>>
> Yes, of course, by running ipfw pipe show ;-)
> There's one confusing thing, though: net.inet.ip.dummynet.io_pkt_drop 
> isn't increasing while around 800-1000 packets per second are being 
> dropped right now. And so "ipfw pipe show" Drp column wouldn't grow 
> either. So it's either not dummynet dropping packets, or a bug (?).


I suspect your interface queues.