[systemd-devel] Improving module loading

Kay Sievers kay at vrfy.org
Tue Dec 23 08:01:01 PST 2014

On Tue, Dec 23, 2014 at 3:22 PM, Tom Gundersen <teg at jklm.no> wrote:
> On Tue, Dec 23, 2014 at 12:25 PM, Hoyer, Marko (ADITG/SW2)
> <mhoyer at de.adit-jv.com> wrote:
>> Some numbers to the above mentioned arguments:
>> - in an idle system, systemd-udev-trigger.service takes by about 150-200ms just to get the complete device tree to send out "add" uevents again (udevd was deactivated while doing this measure)
> I'm working on optimizing this a bit (though we are obviously talking
> about percentage points, not orders of magnitude). I'd be interested
> in seeing if it could be further optimized to help your usecase once I
> have pushed out the basic rework.

This is in most cases caused by conceptually broken implementations of
drivers or subsystems which call into the driver or event the firmware
when the "uevent" file is read by userspace.

Subsystems like "power_supply" had the great idea to transport device
measurement data over uevents. This can't be fixed from userspace, it
would need to be fixed in the kernel.


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