On Thu, Mar 03, 2011 at 01:10:10PM -0500, Mark Lord wrote:
> On 11-03-03 09:58 AM, Philippe De Muyter wrote:
> > Summary :
> >
> > When I started to listen to a USB serial GPS receiver, the interrupts
> > of my sata disk were blocked until reboot :(
>
>
> Blocked until reboot, or until you unplug the GPS/serial thingie from the USB port?
>
>
> > Switching in the BIOS from 'APIC disabled' to 'APIC enabled' made the problem
> > disappear.
> >
> > On Wed, Mar 02, 2011 at 08:34:50AM -0500, Mark Lord wrote:
> >> On 11-03-01 10:00 AM, Philippe De Muyter wrote:
> >>> On Tue, Mar 01, 2011 at 09:16:27AM -0500, Greg KH wrote:
> >>>> On Tue, Mar 01, 2011 at 01:34:52PM +0100, Philippe De Muyter wrote:
> >>>>> previously we had all but one usb interrupts on the same line as ata_piix :
> >>>>> 5: 17183 XT-PIC-XT-PIC ata_piix, ata_piix, ehci_hcd:usb1, ehci_hcd:usb2, uhci_hcd:usb3, uhci_hcd:usb5, uhci_hcd:usb6, uhci_hcd:usb7, uhci_hcd:usb8
> >>>>> while now they are spread on different lines : 16, 18, 19, 21 and 22
> >>>>>
> >>>>> So I wonder if there is still a bug, but that it is not triggered anymore.
> >>>>>
> >>>>> Is there a way to tell which interrupt line the USB GPS receiver is connected
> >>>>> to ?
> >>>>
> >>>> See which USB bus the device is on, using lsusb. It should match up
> >>>> with the usbX number in the above list.
> >>>
> >>> Given that I get :
> >>>
> >>> tmp199:~ # lsusb
> >>> ...
> >>> Bus 007 Device 002: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port
> >>> tmp199:~ # cat /proc/interrupts
> >>> CPU0 CPU1
> >>> ...
> >>> 19: 996143 995511 IO-APIC-fasteoi ata_piix, ata_piix, uhci_hcd:usb5, uhci_hcd:usb7
> >>> tmp199:~ #
> >>>
> >>> my USB GPS receiver and my sata disk still share the same interrupt, I assume ?
> >>>
> >>> What's changed now is that this interrupt line is now IO-APIC-fasteoi instead
> >>> of XT-PIC-XT-PIC. Maybe there's something to look at there ?
> >>>
> >>>>
> >>>> Glad enabling APIC in your BIOS fixed this.
> >>>
> >>> I am glad too :)
> >>
> >> Nothing got "fixed" by doing that.
> >> Swept under the rug, yes.
> >>
> >> But the bug is still there.
> >
> > If it is a bug (what I also believe) it is not a new one :
> >
> > Before installing 2.6.37-20-desktop (opensuse 11.4) on this new hardware,
> > I had the same problem with 2.6.31.14-0.6-desktop (opensuse 11.2) and
> > with 2.6.22.18-0.2-default (opensuse 10.3)
>
> Mmm.. so an old bug. Nasty, those. :)
>
> What is most likely happening here, is that the USB interrupt handler
> is returning IRQ_HANDLED under some condition where IRQ_NONE is required.
>
> In other words, USB thought it got an interrupt, but didn't really,
> but since it returns IRQ_HANDLED regardless, then other
> device drivers sharing that IRQ don't necessarily get called.
> If this happens repeatedly, then it could disrupt the other devices.
>
> Now, that's not overly likely, but then again it's probably not
> well tested with everyone using APICs nowadays.
>
> Or, perhaps the PL2303 driver leaves an interrupt active/pending
> without clearing it in hardware, so the interrupt keeps recurring
> over and over. This (unlikely) is easy to check for, by watching
> the /proc/interrupts count for the USB on your APIC-enabled kernel.
>
> If the numbers increase at a phenomenal rate, then there might
> be an issue. With an active GPS, one would expect the numbers to
> be incrementing steadily, say a few dozen or a hundred or so per second.
I did a small count of the interrupts on the GPS/SATA irq line, with
the GPS listener process running, but no disk activity. Here it is
(IO-APIC-fasteoi mode) :
tmp179:/tmp # cat /proc/interrupts; sleep 10; cat /proc/interrupts
CPU0 CPU1
...
19: 7651 7648 IO-APIC-fasteoi ata_piix, ata_piix, uhci_hcd:usb5, uhci_hcd:usb7
...
19: 8428 8420 IO-APIC-fasteoi ata_piix, ata_piix, uhci_hcd:usb5, uhci_hcd:usb7
...
tmp179:/tmp #
During those 10 seconds, we received about 1500 characters at 4800 bps.
and now without the GPS listener process running :
tmp179:/tmp # cat /proc/interrupts; sleep 10; cat /proc/interrupts
CPU0 CPU1
...
19: 35361 35316 IO-APIC-fasteoi ata_piix, ata_piix, uhci_hcd:usb5, uhci_hcd:usb7
...
19: 35361 35316 IO-APIC-fasteoi ata_piix, ata_piix, uhci_hcd:usb5, uhci_hcd:usb7
...
tmp179:/tmp #
With the XT-PIC mode, the listener process kept running perfectly,
but the interrupt counter in /proc/interrupts did not increase.
>
> Cheers
--
Philippe De Muyter +32 2 6101532 Macq SA rue de l'Aeronef 2 B-1140 Bruxelles
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