Arch Linux

eigrad

Member

Registered: 2009-12-02

Posts: 8

Udev and cdrom

Hi!

I met with problem on Acer Extensa 4230 laptop.

If there are no disk in CD-ROM, udev constantly creates load on the processor (~50% of CPU time). If there is one - it doesn't stop with inactivity.

If udevd is not running, there is a message repeat every 2 seconds in udevadm monitor output:

KERNEL[1259789700.021484] change   /devices/pci0000:00/0000:00:1f.2/host1/target1:0:0/1:0:0:0 (scsi)
KERNEL[1259789702.021523] change   /devices/pci0000:00/0000:00:1f.2/host1/target1:0:0/1:0:0:0 (scsi)

If udevd is running:
KERNEL[1259789861.689635] change   /devices/pci0000:00/0000:00:1f.2/host1/target1:0:0/1:0:0:0/block/sr0 (block)
UDEV  [1259789861.689693] change   /devices/pci0000:00/0000:00:1f.2/host1/target1:0:0/1:0:0:0 (scsi)
KERNEL[1259789861.689940] change   /devices/pci0000:00/0000:00:1f.2/host1/target1:0:0/1:0:0:0/block/sr0 (block)
UDEV  [1259789861.689996] change   /devices/pci0000:00/0000:00:1f.2/host1/target1:0:0/1:0:0:0 (scsi)
KERNEL[1259789861.690132] change   /devices/pci0000:00/0000:00:1f.2/host1/target1:0:0/1:0:0:0/block/sr0 (block)
UDEV  [1259789861.690480] change   /devices/pci0000:00/0000:00:1f.2/host1/target1:0:0/1:0:0:0 (scsi)
...

http://pastebin.ca/1699110 # udevd --debug 2>&1 | head -n 500 | tee udevd.debug
http://pastebin.ca/1699121 # dmesg

jt512

Member

Registered: 2009-02-19

Posts: 262

Re: Udev and cdrom

Try this: http://aur.archlinux.org/packages.php?ID=31373

craw

Member

Registered: 2005-01-06

Posts: 29

Re: Udev and cdrom

Same problem here,

udev-ubuntu does not fix this issue, udevd still spawns way too many processes (~75),  and udev-ubuntu won't detect plugged in usb-devices.
The corresponding messages in udevadm now adress /dev/sda (which is the built in hdd).

*edit*
Must have done something horribly wrong while trying udev-ubuntu from AUR, it works flawlessly, 3 instances of udevd and no more masses of messages visible. Thanks.

So with core/udev-146-2 "udevadm monitor --property" reports thousands of the following messages:

monitor will print the received events for:
UDEV - the event which udev sends out after rule processing
KERNEL - the kernel uevent

KERNEL[1263988080.434902] change   /devices/pci0000:00/0000:00:1f.2/host1/target1:0:0/1:0:0:0/block/sr0 (block)
UDEV_LOG=0
ACTION=change
DEVPATH=/devices/pci0000:00/0000:00:1f.2/host1/target1:0:0/1:0:0:0/block/sr0
SUBSYSTEM=block
DEVNAME=sr0
DEVTYPE=disk
SEQNUM=203956
MAJOR=11
MINOR=0

UDEV  [1263988080.434928] change   /devices/pci0000:00/0000:00:1f.2/host1/target1:0:0/1:0:0:0 (scsi)
UDEV_LOG=0
ACTION=change
DEVPATH=/devices/pci0000:00/0000:00:1f.2/host1/target1:0:0/1:0:0:0
SUBSYSTEM=scsi
SDEV_MEDIA_CHANGE=1
DEVTYPE=scsi_device
DRIVER=sr
MODALIAS=scsi:t-0x05
SEQNUM=190553

KERNEL[1263988080.439683] change   /devices/pci0000:00/0000:00:1f.2/host1/target1:0:0/1:0:0:0/block/sr0 (block)
UDEV_LOG=0
ACTION=change
DEVPATH=/devices/pci0000:00/0000:00:1f.2/host1/target1:0:0/1:0:0:0/block/sr0
SUBSYSTEM=block
DEVNAME=sr0
DEVTYPE=disk
SEQNUM=203957
MAJOR=11
MINOR=0

UDEV  [1263988080.439814] change   /devices/pci0000:00/0000:00:1f.2/host1/target1:0:0/1:0:0:0 (scsi)
UDEV_LOG=0
ACTION=change
DEVPATH=/devices/pci0000:00/0000:00:1f.2/host1/target1:0:0/1:0:0:0
SUBSYSTEM=scsi
SDEV_MEDIA_CHANGE=1
DEVTYPE=scsi_device
DRIVER=sr
MODALIAS=scsi:t-0x05
SEQNUM=190554

The issue seems to be known:
http://bugs.archlinux.org/task/16001
http://bugzilla.kernel.org/show_bug.cgi?id=13783

Only solution seems to be downgrading udev to 141 (with all deps, mainly beeing hal and gstreamer) or waiting for further fixes...

*edit* testing/udev-149 also will not fix this

Last edited by craw (2010-01-20 16:54:27)

craw

Member

Registered: 2005-01-06

Posts: 29

Re: Udev and cdrom

So, after running on udev-ubuntu since my last posting has revealed that it improves the overall situation.
But after running the system for some time know udevd is up to 13 processes again and the "media change" events do still occur.
So there is to say the problem is less severe than with the udev versions from core or testing but still existing.

Hope this will be fixed soon

jt512

Member

Registered: 2009-02-19

Posts: 262

Re: Udev and cdrom

See my fix in post #32 here.

Jay

craw

Member

Registered: 2005-01-06

Posts: 29

Re: Udev and cdrom

I already disabled polling, which does not affect the generation of media changed events on the dvd-drive at all, they do still occur though obviously the media did not change.
System is usable without needing to kill & restart udevd, but it still is misbehaving, all those workarounds improve the effects of udevs behaviour but do not resolve the issue itself.