i386/95267: packet drops periodically appear

[Gosha]

>Number:         95267
>Category:       i386
>Synopsis:       packet drops periodically appear
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-i386
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Apr 03 14:00:35 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator:     Gosha
>Release:        6-STABLE
>Organization:
>Environment:
FreeBSD lagnaden 6.1-PRERELEASE FreeBSD 6.1-PRERELEASE #1: Thu Mar 16 18:36:39 MSK 2006     root at lagnaden:/usr/obj/usr/src/sys/LAGNADEN  i386
>Description:
The system has 2 fxp interfaces, currently working w/o polling. load averages are about 0.5. When network load gets higher, packet drops start to appear:

netstat -d 1:

input        (Total)           output
   packets  errs      bytes    packets  errs      bytes colls drops
      5490     0     352113       9819     0   14682926     0    32
      5891     0     344871      10607     0   14543401     0    77
      5655     0     351419      10578     0   14722751     0    53
      5487     0     369978       9849     0   15743147     0    41
      5840     0     359280      10594     0   15166142     0    62
      5611     0     383657      10879     0   16205605     0    42
      5946     0     353950      10571     0   14549457     0    84
      5913     0     335259      11061     0   14052325     0    62
      5631     0     360135      10048     0   14667789     0    66
      5480     0     367820      10072     0   15327256     0    54
      5674     0     363382      10356     0   14898610     0    51
      5752     0     355121      10637     0   14684370     0    40

network performance degrades greatly when drops are present (latencies get very high). This problem didn't exist on 4.11-stable - it ran smoothly, w/o any drops under any loads.
>How-To-Repeat:
just wait until there are about 40 ftp/smb clients connected.
>Fix:

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