bin/182448: systat -if have invalid counters with 10Gb/s traffic

[Olivier Cochard-Labbe]

>Number:         182448
>Category:       bin
>Synopsis:       systat -if have invalid counters with 10Gb/s traffic
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Sep 27 23:20:00 UTC 2013
>Closed-Date:
>Last-Modified:
>Originator:     Olivier Cochard-Labbe
>Release:        9.2-RC4
>Organization:
BSD Router Project
>Environment:
FreeBSD bsdrp2.orange.bsdrp.net 9.2-RC4 FreeBSD 9.2-RC4 #0 r255473M: Fri Sep 20 23:47:45 CEST 2013     root at orange.bsdrp.net:/usr/obj/BSDRP.amd64/usr/local/BSDRP/BSDRP/FreeBSD/src/sys/amd64  amd64
>Description:
During a 10Gb/s network load test I found that systat didn't display good values with the default 5 seconds refresh (but it's fixed with less than 5 seconds refresh).

Here is an example with "systat -ifstat" + ":scale gbit" :
                    /0   /1   /2   /3   /4   /5   /6   /7   /8   /9   /10
     Load Average   |||

      Interface           Traffic               Peak                Total

            ix0  in      2.964 Gb/s          2.964 Gb/s          143.442 TB
                 out     0.000 Gb/s          0.000 Gb/s            0.566 KB


During the same network load, now with a 1 seconds refresh: "systat -ifstat 1" + ":scale mbit" :

"systat -ifstat" + ":scale mbit" :
                    /0   /1   /2   /3   /4   /5   /6   /7   /8   /9   /10
     Load Average   |||

      Interface           Traffic               Peak                Total
            ix0  in      9.827 Gb/s          9.830 Gb/s          143.396 TB
                 out     0.000 Gb/s          0.000 Gb/s            0.566 KB

=> Notice that the bar "Load Average" didn't change with the new refresh time.
>How-To-Repeat:
just start "systat -ifstat" under high usage of 10Gb/s NIC
>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: