igb netstat input counters 2x?

John-Mark Gurney jmg at funkthat.com
Wed Aug 14 00:27:16 UTC 2019


I'm doing some perf testing on an APU4 board, and I noticed that
it looks like the input netstat counters are 2x than what they should
be.

I was seeing 60MiB/sec via netstat -w 1 -I igb1:
     40034     0     0   60760352       2538     0     177909     0
     40700     0     0   61776228       2574     0     180300     0

But the program was only reading 27MB/sec.  I decided to read the mac
stats directly via:
bytes=$(sysctl -n dev.igb.1.mac_stats.good_octets_recvd); while sleep 1; do
	nbytes=$(sysctl -n dev.igb.1.mac_stats.good_octets_recvd)
	echo $(($nbytes - $bytes)); bytes=$nbytes
done

and saw much more reasonable numbers:
31099740
30512488
30675974

Which is more in line w/ the 27MB/sec that the program reports.

I haven't looked at the code to see what could be causing the double
counting.  Also, the output numbers appear to be accurate.

This is with 13.0-CURRENT from the July 25th snapshot, which is r350322.

-- 
  John-Mark Gurney				Voice: +1 415 225 5579

     "All that I will do, has been done, All that I have, has not."


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