Date: Mon, 7 May 2012 17:25:29 -0700 From: Jack Vogel <jfvogel@gmail.com> To: Vijay Singh <vijju.singh@gmail.com> Cc: freebsd-net@freebsd.org Subject: Re: What does adapter->stats.mpc[] report for ixgbe? Message-ID: <CAFOYbcmQZ0hfWasZDKk9N1v6z_R3KobkURE48M-2Wjyx%2B7j67w@mail.gmail.com> In-Reply-To: <CALCNsJSuG2gUyOZu-PkzaFqt0Vf_aymLf3Jc=czCzW=q9E4t8w@mail.gmail.com> References: <CALCNsJSuG2gUyOZu-PkzaFqt0Vf_aymLf3Jc=czCzW=q9E4t8w@mail.gmail.com>
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This is 'missed packet count', the index has actually been misinterpreted in the code for a while, it was mistakenly associated with queues, but its really per packet buffer, and there are only more than one when there are multiple traffic classes (ala DCB). Even so, only MPC(0) should get incremented anyway. Here is a description: Packets are missed when the receive FIFO has insufficient space to store the incoming packet. This may be caused due to insufficient buffers allocated, or because there is insufficient bandwidth on the IO bus. Events setting this counter also set the receiver overrun interrupt (RXO). These registers do not increment if receive is not enabled and count only packets that would have been posted to the SW driver. Hope this illuminates :) Cheers! Jack On Mon, May 7, 2012 at 5:09 PM, Vijay Singh <vijju.singh@gmail.com> wrote: > Hi, a question for jfv@ or whoever else is familiar with the ixgbe > driver - I am looking at a system where the adapter reports a large > number of ierrors that I traced to this stat. What does this mean? > Intuitively it seems like the receive ring isn't being drained fast > enough but wanted to confirm with the experts. > > -vijay > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org" >
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