High interrupt load under 5.2.1-RELEASE

[Alex Helbig]

Hi Everyone,

I am having some issues with 5.2.1-RELEASE on an Intel SE7500WV2 with
an Intel SRCU42L Raid controller. The issue I have is the number of
interrupts per second being caught by the code for either the em or iir
device. The output of vmstat and top will show what I mean:
%vmstat -i
interrupt                          total       rate
irq1: atkbd0                         163          0
irq6: fdc0                             3          0
irq8: rtc                         803888        127
irq9: em0 em1 iir0+            360580529      57408
irq13: npx0                            1          0
irq15: ata1                           49          0
irq0: clk                         628017         99
Total                          362012650      57636

%top -s
last pid:   829;  load averages:  0.89,  0.71,  0.62
54 processes:  5 running, 41 sleeping, 7 waiting, 1 lock
CPU states:  0.1% user,  0.0% nice,  0.4% system, 14.4% interrupt, 85.2% idle
Mem: 6944K Active, 6012K Inact, 39M Wired, 9312K Buf, 1952M Free Swap: 
4071M Total, 4071M Free

   PID USERNAME PRI NICE   SIZE    RES 
STATE  C   TIME   WCPU    CPU     COMMAND
    11 root     -16    0     0K    12K CPU3   3 104:59 99.02% 
99.02%     idle: cpu3
    12 root     -16    0     0K    12K RUN    2 104:58 99.02% 
99.02%     idle: cpu2
    13 root     -16    0     0K    12K CPU1   1 104:42 99.02% 
99.02%     idle: cpu1
    22 root     -68 -187     0K    12K *Giant 0  61:32 55.18% 
55.18%     irq9: em0 em1 iir0+
    14 root     -16    0     0K    12K CPU0   0  42:46 40.77% 
40.77%     idle: cpu0
   829 alexh    -68    0  2208K  1468K CPU2   2   0:00  6.66%  0.63%     top

%dmesg | head -n 15
Copyright (c) 1992-2004 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 5.2.1-RELEASE #0: Mon Feb 23 20:45:55 GMT 2004
     root at wv1u.btc.adaptec.com:/usr/obj/usr/src/sys/GENERIC
Preloaded elf kernel "/boot/kernel/kernel" at 0xc0a35000.
Preloaded elf module "/boot/kernel/acpi.ko" at 0xc0a35244.
ACPI APIC Table: <INTEL  SWV20   >
Timecounter "i8254" frequency 1193182 Hz quality 0
CPU: Intel(R) XEON(TM) CPU 2.40GHz (2392.95-MHz 686-class CPU)
   Origin = "GenuineIntel"  Id = 0xf24  Stepping = 4

Features=0x3febfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM>
   Hyperthreading: 2 logical CPUs
real memory  = 2147418112 (2047 MB)
avail memory = 2080645120 (1984 MB)


The points that seem relevant to me in diagnosing this are:
* This is a default install of 5.2.1-RELEASE. No custom kernel, no
additional software installed.
* The box is currently doing nothing other than sitting in a rack
* The same box with 5.1-RELEASE did not exhibit this behavior
* It seems that the em and iir devices are all sitting behind IRQ9 - I
suspect this is not a good thing for when the box does become loaded

Does anyone have any suggestions that may either clarify my problem or
help me resolve it.

Please reply to me and to the list as I am not currently subscribed.

Thanks in advance
Alex Helbig.



-------------------------------------------------
Alex Helbig
Head of IT Services

Redeemer Lutheran College
745 Rochedale Rd
Rochedale Q 4123
Australia
Ph:   +61 7 3341 4555
Fax:  +61 7 3341 9143