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Date:      Sun, 25 May 2003 11:01:16 +0800
From:      "Paul Hamilton" <paulh@bdug.org.au>
To:        "Freebsd-Questions" <freebsd-questions@FreeBSD.ORG>
Subject:   RE: 'top' showing high interrupt rate
Message-ID:  <AGEHIFHGNEMPFNCPLONMOEKGEKAA.paulh@bdug.org.au>
In-Reply-To: <AGEHIFHGNEMPFNCPLONMOEFPEKAA.paul@compwest.com.au>

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Thanks for the reply's. I didn't see them on the list.
Maybe I missed them, so I have pasted them back in here.
--------------------------------------------------------------------
By any chance, have you altered the system quantum (HZ), or enabled
kern.polling?
-Chuck

Run systat and then type ":vmstat" (without quotes) to get the vmstat
screen.

The lower right will have interrupts broken down by device ... this should
help.
-Bill Moran

Try `top -S` instead. This will show system processes as well. Also, use
`systat -v` as previously mentioned to see interrupt counts.
My guess is this box is a gateway/firewall and may be getting pounded on
the network interfaces. Are you running ipfw as well?
- Andy Farkas
--------------------------------------------------------------------
Thanks guys!

I tried: sysctl kern.polling and got:-
	sysctl: unknown oid 'kern.polling'
I haven't played around with the system quantum.

I like the systat --> :vmstat and the systat -v command.  Very nice!

Here is a dump of what is going on.  As you can see, it doesn't show very
much:-
----------------------------------------------------------------------------
--
    1 users    Load  0.21  0.17  0.20                  May 25 10:32

Mem:KB    REAL            VIRTUAL                     VN PAGER  SWAP PAGER
        Tot   Share      Tot    Share    Free         in  out     in  out
Act    6320     784    13460      944    7616 count
All   24800    1880  2328768     3408         pages
                                                          zfod   Interrupts
Proc:r  p  d  s  w    Csw  Trp  Sys  Int  Sof  Flt        cow     241 total
     1        7        20        99  241   11    2   7600 wire        ata0
irq14
                                                     8568 act         ata1
irq15
 0.2%Sys  59.7%Intr  0.6%User  0.0%Nice 39.5%Idl     5284 inact     4 dc0
irq10
|    |    |    |    |    |    |    |    |    |       3348 cache       fdc0
irq6
++++++++++++++++++++++++++++++                       4268 free      9 sio1
irq3
                                                          daefr   100 clk
irq0
Namei         Name-cache    Dir-cache                     prcfr   128 rtc
irq8
    Calls     hits    %     hits    %                     react
        3        3  100                                   pdwake
                                                          pdpgs
Disks   ad0   ad1  acd0   fd0   md0                       intrn
KB/t   0.00  0.00  0.00  0.00  0.00                  6480 buf
tps       0     0     0     0     0                     3 dirtybuf
MB/s   0.00  0.00  0.00  0.00  0.00                  2348 desiredvnodes
% busy    0     0     0     0     0                  2374 numvnodes
                                                     1160 freevnodes
----------------------------------------------------------------------------
--

Yes, this PC is a gateway to the internet via a modem (see dc0 and sio1
showing activity).

I have tried the ststat -v on 3 or 4 servers, and they all pretty much show
that clk and rtc use 100/128.
However, most of them run at ~15% interupt activity.  Hmm, maybe it's 60% on
this server,
because it's only a Pentium 166.

Anyone else have an insight on this?

Hmm, I then tried killing natd, and lo-and-behold, interrupts fell to 0.5%!!

Restarted natd and interrupts are still < 0.5%!  Here is the natd via top
before and after:-


	108 root            2   0   464K   152K select  96:45  0.00%  0.00% natd
	15462 root            2   0   420K   272K select   0:00  0.00%  0.00% natd

The only difference is the size and res.  Anyone know of problems with natd?
The server was acting ok, just reporting that the interrupt usage was
running at 60%.
I will keep an eye on this over the next few days.

Cheers,

Paul Hamilton


-----Original Message-----
From: owner-freebsd-questions@freebsd.org
[mailto:owner-freebsd-questions@freebsd.org]On Behalf Of Paul Hamilton
Sent: Wednesday, 21 May 2003 10:38 PM
To: Freebsd-Questions
Subject: 'top' showing high interrupt rate


Hi,

I noticed that top shows a rather high interrupt rate, usually hovering
around 60%!  Here is a sample:-

last pid:  2879;  load averages:  0.34,  0.24,  0.18
up 1+17:26:56  17:18:10
36 processes:  2 running, 33 sleeping, 1 zombie
CPU states:  0.6% user,  0.0% nice,  0.0% system, 59.8% interrupt, 39.6%
idle
Mem: 11M Active, 5072K Inact, 7988K Wired, 3552K Cache, 6480K Buf, 960K Free
Swap: 128M Total, 4608K Used, 123M Free, 3% Inuse

  PID USERNAME      PRI NICE  SIZE    RES STATE    TIME   WCPU    CPU
COMMAND
  135 root           10   0   980K   528K nanslp  11:38  0.00%  0.00% cron
  201 root            2   0  2824K  1132K select   3:46  0.00%  0.00% ppp
  108 root            2   0   452K   208K select   0:29  0.00%  0.00% natd
  127 root            2   0  2760K  1704K select   0:14  0.00%  0.00% named
  223 root            2   0  2068K   908K select   0:10  0.00%  0.00% sshd
  212 root            2   0  2044K   876K select   0:10  0.00%  0.00% sshd
<snip>

pstat -T says:

	120/1064 files
	4M/127M swap space

vmstat 10 says:


 procs      memory      page                    disks     faults      cpu
 r b w     avm    fre  flt  re  pi  po  fr  sr ad0 ad1   in   sy  cs us sy
id
 0 0 0   12992   4992    1   0   0   0   1   0   0   0  237   52   8  0 59
41
 0 0 0    9404   4992    1   0   0   0   0   0   0   0  229   35   6  0 60
40
 0 0 0   15572   4868   16   0   0   0   7   0   0   0  231  938  10  1 61
38
 0 0 0   17820   4868    8   0   0   0   0   0   1   0  230   45   8  0 60
40
 0 0 0   12492   5224    8   0   0   0   9   0   0   0  231   47   8  1 60
39

dmesg says:

Copyright (c) 1992-2000 The FreeBSD Project.
Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
        The Regents of the University of California. All rights reserved.
FreeBSD 4.2-RELEASE #1: Tue Feb 13 22:51:23 WST 2001
    root@ant.compwest.net.au:/usr/src/sys/compile/ANT
Timecounter "i8254"  frequency 1193182 Hz
CPU: Pentium/P55C (165.79-MHz 586-class CPU)
  Origin = "GenuineIntel"  Id = 0x544  Stepping = 4
  Features=0x8001bf<FPU,VME,DE,PSE,TSC,MSR,MCE,CX8,MMX>
real memory  = 33554432 (32768K bytes)
avail memory = 29478912 (28788K bytes)

Yes, the server only has 32MB or RAM, however, it's only using 4MB of VM.

Anyone have any idea how to troubleshoot further?  How can I isolate what is
causing the rather high interrupt rate?

Cheers,

Paul Hamilton


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