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Date: Thu, 27 Feb 2014 18:16:21 -0500 (EST)
From: Rick Macklem <rmacklem@uoguelph.ca>
To: Ryan Stone <rysto32@gmail.com>
Message-ID: <917817504.14529709.1393542981376.JavaMail.root@uoguelph.ca>
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Subject: Re: Network loss
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Cc: Johan Kooijman <mail@johankooijman.com>,
 freebsd-net <freebsd-net@freebsd.org>, Jack Vogel <jfvogel@gmail.com>,
 John Baldwin <jhb@freebsd.org>
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Ryan Stone wrote:
> On Wed, Feb 26, 2014 at 8:00 PM, Rick Macklem <rmacklem@uoguelph.ca>
> wrote:
> > And please email if you try it and let us know if it helps.
> >
> > I've think I've figured out how 64K NFS read replies can do this,
> > but I'll admit "ping" is a mystery? (Doesn't it just send a single
> > packet that would be in a single mbuf?)
> 
> ixgbe currently returns an error from its if_transmit function if it
> gets an error sending *any* packet that is queued for transmit.  So
> if
> there is a 64K NFS request queued then ping could see an EFBIG error.
> I can't explain the packet loss, unless ping is counting errors from
> send() as lost packets (which would be completely reasonable).
Yep, I just noticed that when I took another glance at the driver.
(Things still look a bit weird, since if m_defrag() returns NULL, the
 second attempt fails with ENOBUFS in ixgbe_xmit(). It seems that
 m_defrag() returns a new mbuf list, but it is still > 32 mbufs in
 length?)

rick

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