Date: Mon, 7 May 2012 21:35:33 -0700 From: Jack Vogel <jfvogel@gmail.com> To: Juli Mallett <jmallett@freebsd.org> Cc: freebsd-net@freebsd.org, Vijay Singh <vijju.singh@gmail.com> Subject: Re: What does adapter->stats.mpc[] report for ixgbe? Message-ID: <CAFOYbc=O4w2H8FN8t0pQiJKp2fNMGOtsN5TfZJ3GoX4YnijTcw@mail.gmail.com> In-Reply-To: <CACVs6=9kNzB6sDXE1jPKKQCR8LD7h98ME7hFrKqtasUf-RCBwQ@mail.gmail.com> References: <CALCNsJSuG2gUyOZu-PkzaFqt0Vf_aymLf3Jc=czCzW=q9E4t8w@mail.gmail.com> <CAFOYbcmQZ0hfWasZDKk9N1v6z_R3KobkURE48M-2Wjyx%2B7j67w@mail.gmail.com> <CACVs6=9kNzB6sDXE1jPKKQCR8LD7h98ME7hFrKqtasUf-RCBwQ@mail.gmail.com>
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On Mon, May 7, 2012 at 5:31 PM, Juli Mallett <jmallett@freebsd.org> wrote: > While we're on the subject, I've had some confusion for some time now: > > On Mon, May 7, 2012 at 5:25 PM, Jack Vogel <jfvogel@gmail.com> wrote: > > Packets are missed when the receive FIFO has insufficient space to store > the > > incoming packet. > > This means the on-card FIFO, i.e. the fixed-size FIFO that is divided > into receive and transmit space by the driver, right? And the > separate "receive no buffers" counter records instances where the > packet made it to the card but there was no buffer associated with a > receive descriptor to write it to? That has been my interpretation of > the documentation and the numbers I've seen in practice, but I've seen > conflicting interpretations and would much rather hear it from the > horse's mouth :) > > Thanks, > Juli. > Gee, not sure if I like being called a horse :) But yes you are correct. When you have multiple traffic classes, as it is when you have DCB, then the packet buffer may be partitioned into up to 8 parts. This would let you seperate say FCOE and iSCSI from normal net traffic. But for now in FreeBSD its just one which is divided into 3 parts: TX, RX, and FDIR (flow director). Cheers, Jack
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