[systemd-devel] Reduce unit-loading time

[cee1]

2015-05-17 17:45 GMT+08:00 Martin Pitt <martin.pitt at ubuntu.com>:
> Hello cee,
>
> cee1 [2015-05-16  0:46 +0800]:
>> 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.
>
> You probably want to use some readahead solution. We found that it
> makes a significant improvement on ARM boards with slow MMC cards.
>
> Martin
> --
> Martin Pitt                        | http://www.piware.de
> Ubuntu Developer (www.ubuntu.com)  | Debian Developer  (www.debian.org)

Hey,

Thanks for the suggestion, IIRC, sequential read is also beneficial
for flash storage.

Does the readahead-*.service shipped with systemd work for you?


BTW,  some suggestions and questions :)

Suggestion:
I use the following command to figure out why my service is scheduled
at the time:
"systemctl list-dependencies --after target.service"
    and expect it could output "timing info(unit starting time and
started time, etc)" of dependent units.

Question:
How does systemd schedule two services that can be launched in parallel?

I found that,  A and B, if specifies "Before=A", B will start first,
otherwise, B will start at a very late time.


-- 
Regards,

- cee1