May be misconfigured interrupt SMP affinity.See if this link helps:
http://www.alexandersandler.net/smp-affinity-and-proper-interrupt-handling-in-linux
Regards
Mayur
On Thu, Dec 11, 2008 at 1:22 PM, Ranjan Sinha <rnjn.sinha@xxxxxxxxx> wrote:
Hi,
I had asked this question about a year or two back, and unfortunately
i still haven't quite understood this. A sense of deja vu. I have a
dual core machine running Ubuntu 8.10 with the kernel supplied by the
distribution. Here are the details some irrelevant information
stripped off
~$ cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 14
model name : Genuine Intel(R) CPU T2400 @ 1.83GHz
stepping : 8
cpu MHz : 1833.000
cache size : 2048 KB
physical id : 0
siblings : 2
core id : 0
cpu cores : 2
processor : 1
vendor_id : GenuineIntel
cpu family : 6
model : 14
model name : Genuine Intel(R) CPU T2400 @ 1.83GHz
stepping : 8
cpu MHz : 1833.000
cache size : 2048 KB
physical id : 0
siblings : 2
core id : 1
cpu cores : 2
~$ uname -a
Linux Noi1-501468 2.6.27-9-generic #1 SMP Thu Nov 20 21:57:00 UTC 2008
i686 GNU/Linux
The config file for this kernel has the following settings
CONFIG_SMP=y
CONFIG_SCHED_MC=y
CONFIG_SCHED_SMT=y
and yet this is status of interrupts
~$ cat /proc/interrupts
CPU0 CPU1
0: 1847795 0 IO-APIC-edge timer
1: 3518 0 IO-APIC-edge i8042
4: 4 0 IO-APIC-edge
8: 168 0 IO-APIC-edge rtc0
9: 15 0 IO-APIC-fasteoi acpi
12: 30659 0 IO-APIC-edge i8042
14: 58736 0 IO-APIC-edge ata_piix
15: 177814 0 IO-APIC-edge ata_piix
16: 967299 0 IO-APIC-fasteoi i915@pci:0000:00:02.0
18: 7 0 IO-APIC-fasteoi yenta
20: 423 0 IO-APIC-fasteoi uhci_hcd:usb1, ehci_hcd:usb5
21: 37050 0 IO-APIC-fasteoi uhci_hcd:usb2, HDA Intel
22: 0 0 IO-APIC-fasteoi uhci_hcd:usb3
23: 0 0 IO-APIC-fasteoi uhci_hcd:usb4
219: 1407645 0 PCI-MSI-edge iwl3945
220: 223391 0 PCI-MSI-edge eth0
NMI: 0 0 Non-maskable interrupts
LOC: 380806 1332287 Local timer interrupts
RES: 310807 321674 Rescheduling interrupts
CAL: 144202 161332 function call interrupts
TLB: 1281 1087 TLB shootdowns
SPU: 0 0 Spurious interrupts
ERR: 0
MIS: 0
All interrupt processing happening only on CPU0. Installing older
irqbalance does not seem to be an option here. What could be the
reason. Is there a bug in APIC? Or am I missing something?
--
Regards,
Ranjan
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