Greetings,
One line: Frame grabber times out if ntpd runs with kernel calls
Full: We run the bttv frame grabber on a Dell-2600 running
2.6.9-1.667smp (ala Fedora Core 3). If we run ntpd
normally, after a variable amount of time (seconds to
multiple hours), ioctl(dev,VIDIOC_DQBUF,ptr) returns
EINVAL. After putting debug writes in the kernel,
we determined that it is because the request timed out
due to the fact that the interupt was blocked by a
higher priority interupt: the kernel logic for the ntpd
system calls.
This doesn't happen on all systems (e.g. a Dell-2650 doesn't
seem to have this problem), but it will happen with earlier
versions of the kernel. Also, the problem occurs even if
you have stopped ntpd and re-loaded the bttv driver.
It may be that this can occur under more circumstances than
outline above but that it is much rarer. We believe that
the Dell-2600s multiple PCI busses and its interupt structure
may make it much more sensitive to having interupts blocked
for long periods of time.
Keywords: bttv adjtime VIDIOC_DQBUF timeout
Version: 2.6.9-1.667smp
Workaround: Add "disable kernel" to ntp.conf file and reboot
Oops output:
Shell script:
Environment:
Software:
Processor: i686 Genuine Intel 2.8GHZ (Dell-2600)
Modules:
Loaded drivers:
Hardware:
lspci:
SCSI:
Comments: Considering how easy the work-around for us is, this is
pretty low priority (though it was mighty high until we
figured out that ntpd was the thing hogging the interupts).
I wanted to send this in just to make people aware that
there maybe some timing conflicts.
sure
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
