[systemd-devel] systemd-udev causes slow boot and high load

Marco Steinacher mailinglists at websource.ch
Tue May 19 09:32:59 PDT 2015

Am 19.05.2015 um 12:37 schrieb Lennart Poettering:
> On Tue, 19.05.15 12:02, Marco Steinacher (mailinglists at websource.ch) wrote:
>> Hi,
>> After upgrading my system to Debian jessie and switching to systemd I
>> have the following problem:
>> 1. During boot there is the message
>> [    **] A start job is running for udev Wait for Complete De...on (11s
>> / 3min)
>> after "systemd-fsck[452]: /dev/sda5: clean" and it takes about 2 minutes
>> until the boot process continues.
>> systemd-analyze blame shows:
>>   2min 2.945s systemd-udev-settle.service
> systemd-udev-settle.service just waits for devices to be probed. It
> will wait for the kernel drivers to initialize and the udev rules to
> be pliugged in.
> In fact, there's really no need to have this in the boot process at
> all, unless you are using some broken software that assumes that
> there's a point in time where all hardware has been plugged in, but
> such a point in time does not actually exist, and hasn't existed in a
> long time (simply because USB and other busses can take any time they
> want before initialization is complete and the devices have shown up).
>> 2. dmesg also shows:
>> [  254.305831] INFO: task systemd-udevd:296 blocked for more than 120
>> seconds.
>> [  254.305962]       Not tainted 3.16.0-4-686-pae #1
>> [  254.306069] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
>> disables this message.
>> [  254.306165] systemd-udevd   D 00000000     0   296    234 0x00000004
>> and similar messages for the tasks systemd-udevd:308 and
>> systemd-udevd:307. The messages repeat a couple of times (see full log
>> below).
> There you go: your kernel is hung, some driver or your xen irq
> handling is borked and hangs during initialization. This is a kernel
> problem, please report this to the kernel bugzilla.

Thank you for the swift reply and for clarifying the situation.  I
understand now that this is a kernel issue and not a problem with
systemd.  I'll try to track down the kernel issue now.


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