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Date:      Fri, 5 Mar 2010 09:56:39 -0800
From:      Pyun YongHyeon <pyunyh@gmail.com>
To:        Ian FREISLICH <ianf@clue.co.za>
Cc:        current@freebsd.org
Subject:   Re: dev.bce.X.com_no_buffers increasing and packet loss
Message-ID:  <20100305175639.GB14818@michelle.cdnetworks.com>
In-Reply-To: <E1NnVaT-0003Ft-3p@clue.co.za>
References:  <E1NnVaT-0003Ft-3p@clue.co.za>

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On Fri, Mar 05, 2010 at 01:20:57PM +0200, Ian FREISLICH wrote:
> Hi
> 
> I have a system that is experiencing mild to severe packet loss.
> The interfaces are configured as follows:
> 
> lagg0: bce0, bce1, bce2, bce3  lagproto lacp
> 
> lagg0 then is used as the hwdev for the vlan interfaces.
> 
> I have pf with a few queues for bandwidth management.
> 
> There isn't that much traffic on it (200-500Mbit/s).
> 
> I see only the following suspect for packet loss:
> 
> dev.bce.0.com_no_buffers: 140151466
> dev.bce.1.com_no_buffers: 514723247
> dev.bce.2.com_no_buffers: 10454050
> dev.bce.3.com_no_buffers: 369371
> 
> Most of the time, these numbers are static, but every once in a
> while they increase massively by several thousand, but only on 2
> interfaces.  The 1 minute average rate on those interfaces is 266/s
> and 123/s.
> 
> Does anyone think this is related to the packet loss or are these
> counters just a red herring?  Is there anything that can be done
> to reduce this count?
> 

I think this sysctl node indicates number of dropped frames in
completion processor of NetXtreme II. The counter is incremented
when the processor received a frame successfully but it couldn't
pass the frame to system as there are no available RX buffers so
completion processor dopped the received frame.
If you see mbuf shortage from netstat that would be normal. But if
system has a lot of free mbuf resources it may indicate other
issue. bce(4) may not be able to replenish controller with RX
buffer if system is suffering from high load.



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