[systemd-devel] Reduce unit-loading time

[cee1]

Hey,

Thanks for the suggestion, it was other processes running in parallel
which presumably consuming lots of IO, after sending SIGSTOP at the
first (and SIGCONT later), the unit loading time is decreased to
~100ms.


2015-05-13 19:38 GMT+08:00 Hoyer, Marko (ADITG/SW2) <mhoyer at de.adit-jv.com>:
> Hi,
>
>> -----Original Message-----
>> From: systemd-devel [mailto:systemd-devel-
>> bounces at lists.freedesktop.org] On Behalf Of cee1
>> Sent: Wednesday, May 13, 2015 11:52 AM
>> To: systemd Mailing List
>> Subject: [systemd-devel] Reduce unit-loading time
>>
>> Hi all,
>>
>> We're trying systemd to boot up an ARM board, and find systemd uses
>> more than one second to load units.
>
> This sounds far a bit too long to me. Our systemd comes up in an arm based system in about 200-300ms from executing init up to the first unit being executed.
>
>>
>> Comparing with the init of Android on the same board, it manages to
>> boot the system very fast.
>>
>> We guess following factors are involved:
>> 1. systemd has a much bigger footprint than the init of Android: the
>> latter is static linked, and is about 1xxKB (systemd is about 1.4MB,
>> and is linked with libc/libcap/libpthread, etc)
>>
>> 2. systemd spends quiet a while to read/parse unit files.
>
> This depends on the numbers of units involved in the startup (finally connected in the dependency tree that ends in the default.target root). In our case, a comparable large unit set takes by about 40-60ms, not so long, I'd say.
>
>>
>>
>> Any idea to reduce the unit-loading time?
>> e.g. one-single file contains all units descriptions, or a "compiled
>> version"(containing resolved dependencies, or even the boot up
>> sequence)
>
> Could you provide me some additional information about your system setup?
>
> - Version of systemd
> - Are you starting something in parallel to systemd which might take significant IO?
> - Version of the kernel
> - The kernel ticker frequency
> - The enabled cgroups controllers
>
> The last three points might sound a bit far away, but I've an idea in mind ...
>
> Best regards
>
> Marko Hoyer
> Software Group II (ADITG/SW2)
>
> Tel. +49 5121 49 6948
>



-- 
Regards,

- cee1