P4 SMP load balancing

Sean Cavanaugh (seanc@gearboxsoftware.com)
Fri, 12 Oct 2001 04:28:19 -0500


I posted this a while back in linux-smp (which seems like a dead list?)

I have several P4 Xeon SMP systems (Supermicro P4DCE, Intel i860
chipset)

ovendev:~# cat /proc/interrupts
CPU0 CPU1
0: 6348212 0 IO-APIC-edge timer
1: 2 0 IO-APIC-edge keyboard
2: 0 0 XT-PIC cascade
8: 1 0 IO-APIC-edge rtc
9: 0 0 IO-APIC-edge acpi
16: 92620 0 IO-APIC-level eth0
18: 5085 0 IO-APIC-level aic7xxx, aic7xxx
NMI: 0 0
LOC: 6348388 6348427
ERR: 0
MIS: 0

How much of a problem is this really? The program's I am
running on these systems (I have 9 of them) seem do ok right now.
Currently the jobs running on them are heavily CPU bound and don't do
any I/O, but this is going to change when I link them up over a private
network so they can work together on some distributable jobs). I am
running 2.4.10 on most of them, and 2.4.10-ac10 on my developer system
in the farm. The only difference this newer kernel seems to have made
from older ones is that there is only one 'warning unexpected IO-APIC'
message in my startup instead of two.

Snippet from dmesg:

CPU1: Intel(R) Xeon(TM) CPU 1700MHz stepping 0a
Total of 2 processors activated (6723.99 BogoMIPS).
ENABLING IO-APIC IRQs
...changing IO-APIC physical APIC ID to 2 ... ok.
init IO_APIC IRQs
IO-APIC (apicid-pin) 2-0, 2-5, 2-10, 2-11, 2-12, 2-17, 2-20, 2-21, 2-22
not connected.
..TIMER: vector=0x31 pin1=2 pin2=0
number of MP IRQ sources: 18.
number of IO-APIC #2 registers: 24.
testing the IO APIC.......................

IO APIC #2......
.... register #00: 02000000
....... : physical APIC id: 02
.... register #01: 00178020
....... : max redirection entries: 0017
....... : PRQ implemented: 1
....... : IO APIC version: 0020
WARNING: unexpected IO-APIC, please mail
to linux-smp@vger.kernel.org
.... register #02: 00000000
....... : arbitration: 00
.... IRQ redirection table:
<snip>

- Sean

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