Packet passing performance study on exotic hardware.

Gerrit Nagelhout gnagelhout at
Fri Oct 8 07:23:19 PDT 2004

David Gilbert Wrote:
>   - with polling and excessive packets, it doesn't "receive" the full
>     load of packets.  In netstat -w, they show as input "errors"
>     although the number of "errors" isn't strictly related to the
>     number of dropped packets.  It's just some large number that
>     generally increases with the number of dropped packets.

In em_update_stats_counters, errors is calculated as follows:

	/* Rx Errors */
	ifp->if_ierrors =
	adapter->dropped_pkts +
	adapter->stats.rxerrc +
	adapter->stats.crcerrs +
	adapter->stats.algnerrc +
	adapter->stats.rlec + adapter->stats.rnbc + 
	adapter->stats.mpc + adapter->stats.cexterr;

The extra errors you are talking about come from doing mpc + rnbc.  
Only mpc (missed packet count) (and the other errors of course) should 
be used. 
Rnbc is an indication of the internal buffer filling up, but not yet 
dropping packets, and should not be included.


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