On Wednesday, September 12, 2007, Randy Dunlap wrote:
> On Wed, 12 Sep 2007 08:33:15 -0700 Jesse Barnes wrote:
> > I just narrowed down a weird problem where I was losing more than
> > 50% of my vblank interrupts to what seems to be the hires timers
> > patch. Stock 2.6.23-rc5 works fine, but the latest (171) kernel
> > from rawhide drops most of my interrupts unless I also have another
> > interrupt source running (e.g. if I hold down a key or move the
> > mouse I get the expected number of vblank interrupts, otherwise I
> > get between 3 and 30 instead of the expected 60 per second).
> >
> > Any ideas? It seems like it might be bad APIC programming, but I
> > haven't gone through those mods to look for suspects...
>
> Also tickless? (NO_HZ ?)
>
> I think I've seen some emails about tickless and keystrokes being
> needed to cause interrupts... but I'm not postive about it.
>
> but you said "any ideas"
Yeah, there's NO_HZ in the rawhide kernel too, but I'm getting timer
ticks normally afaict, it's just vblank interrupts that get lost...
/proc/interrupts on this machine (from NO_HZ, hires kernel):
[jbarnes@jbarnes-t61 ~]$ cat /proc/interrupts
CPU0 CPU1
0: 290050 289541 IO-APIC-edge timer
1: 3862 3956 IO-APIC-edge i8042
8: 0 0 IO-APIC-edge rtc0
9: 1632 1643 IO-APIC-fasteoi acpi
12: 183662 183926 IO-APIC-edge i8042
14: 20626 20717 IO-APIC-edge libata
15: 0 0 IO-APIC-edge libata
16: 46812 46825 IO-APIC-fasteoi yenta, uhci_hcd:usb3, i915@pci:0000:00:02.0
17: 63715 63653 IO-APIC-fasteoi uhci_hcd:usb4, HDA Intel, firewire_ohci, iwl4965
18: 0 0 IO-APIC-fasteoi uhci_hcd:usb5
19: 52 36 IO-APIC-fasteoi ehci_hcd:usb7
20: 43 46 IO-APIC-fasteoi uhci_hcd:usb1
21: 0 0 IO-APIC-fasteoi uhci_hcd:usb2
22: 2 1 IO-APIC-fasteoi ehci_hcd:usb6
2297: 937 944 PCI-MSI-edge eth0
2298: 12392 12402 PCI-MSI-edge ahci
NMI: 0 0
LOC: 290913 335027
ERR: 0
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