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Date: Sun, 6 Feb 2000 12:01:10 +0900 (JST)
From: amagai@nue.org
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To: FreeBSD-gnats-submit@freebsd.org
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Subject: kern/16510: User processes locked on SMP box while burst packet receiving and tcpdumping
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>Number:         16510
>Category:       kern
>Synopsis:       User processes locked on SMP box while burst packet receiving and tcpdumping
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat Feb  5 19:10:01 PST 2000
>Closed-Date:
>Last-Modified:
>Originator:     Y.Amagai
>Release:        FreeBSD 3.4-STABLE i386
>Organization:
New Unified Environment Research Project
>Environment:
Host S; PenIII 618M , ASUS P2BF
        NIC PLANEX ENW9501 (DEC 21140-A?) 100Base/TX full duplex
        single CPU, FreeBSD 2.2.8-Stable

Host D; PenIII 618M * 2 , MB TYAN S1832DL Tiger100
        PLANEX ENW9501 (DEC 21140-A?) 100Base/TX full duplex
        dual CPU, FreeBSD 3.4-Stable, SMP configured

Host S => 3Com Switch 3300 => Host D
>Description:
on HostS;  ping -f -l 5000000 -s 1 hostD >/dev/null
on HostD;  tcpdump >/dev/null

  No tcpdump running on hostD;
hostD reciving packets about 60000 Packets per Second (pps),
hostS sending  packets about 60000 pps
hostD CPU interrupt about 46 %  (by /usr/bin/top)

  while tcpdump running on hostD;
on HostD, user processes (netstat, top ...) are locked (or are eager for 
CPU time silce) .
hostS sending about 80000 pps!!
Kill the ping process on hostS, netstat resume, and reports many input packtes
received.

  So, while tcpdump (or packet duplicate in BPF routine), all CPU time 
slice may consume in interrupt routines.

  Without SMP configuration on hostD, user processes are not locked.

  No tcpdump running on hostD;
hostD reciving packets about 46000 pps
hostS sending  packets about 46000 pps
hostD CPU interrupt about 60 %

  while tcpdump running on hostD;
hostD reciving packets about 44000 pps
hostS sending  packets about 44000 pps
hostD CPU interrupt about 60 %
>How-To-Repeat:
as above.
>Fix:
Sorry, I don't know.

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


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