Hi all,
I've got this niggling problem that I revisit every time a new kernel is
released for FC4, however, it doesn't appear to change:
On my notebook it seems that by default most devices are sharing IRQ10,
including the ones I would normally associate with performance (disk,
net):
$ cat /proc/interrupts
CPU0
0: 34756 XT-PIC timer
1: 91 XT-PIC i8042
2: 0 XT-PIC cascade
8: 1 XT-PIC rtc
9: 1138 XT-PIC acpi
10: 10853 XT-PIC libata, ipw2200, Intel ICH6, ehci_hcd:usb1,
uhci_hcd:usb2, uhci_hcd:usb3, uhci_hcd:usb4, uhci_hcd:usb5, yenta, ohci1394, eth0
12: 814 XT-PIC i8042
14: 454 XT-PIC ide0
NMI: 0
ERR: 0
The interrupts are assigned by ACPI. Since I need ACPI for cpuspeed I
don't want to disable it altogether, but instead fiddled with boot
parameters to keep it from doing the IRQ assignment. For example, my
current boot command line contains "pci=noacpi,routeirq", which seems to
improve the situation:
$ cat /proc/interrupts
CPU0
0: 54122 XT-PIC timer
1: 73 XT-PIC i8042
2: 0 XT-PIC cascade
5: 399 XT-PIC uhci_hcd:usb3, ohci1394, eth0
7: 2 XT-PIC ehci_hcd:usb1, uhci_hcd:usb2
8: 1 XT-PIC rtc
9: 1727 XT-PIC acpi
10: 41 XT-PIC ipw2200, Intel ICH6, uhci_hcd:usb4, yenta
11: 10615 XT-PIC libata, uhci_hcd:usb5
12: 118 XT-PIC i8042
14: 610 XT-PIC ide0
NMI: 0
ERR: 0
With this, the interrupts are much more evenly used.
Now, I guess my question is, does this even matter? Is sharing a single
IRQ among many devices a potential performance issue? Am I losing
anything by stopping ACPI from messing with IRQ's?
Cheers
Steffen.
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