[systemd-devel] Reduce unit-loading time
lennart at poettering.net
Mon May 18 09:24:36 PDT 2015
On Mon, 18.05.15 18:24, cee1 (fykcee1 at gmail.com) wrote:
> 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)
> Thanks for the suggestion, IIRC, sequential read is also beneficial
> for flash storage.
> Does the readahead-*.service shipped with systemd work for you?
We removed the readahead logic from systemd a while back, since it had
no maintainer, and nobody wanted to pick it up.
> How does systemd schedule two services that can be launched in
It's not defined. systemd will fork things of in an undefined order if
ther are multiple units runnable at the same time.
As mentioned elsewhere, I'd be willing to merge a patchat that changes
this and allows control of what service is forked off first, via some
per-unit Priority= setting or so.
Lennart Poettering, Red Hat
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