[systemd-devel] Reduce unit-loading time

[Cristian Rodríguez]

On Tue, May 19, 2015 at 5:39 PM, Cristian Rodríguez
<crrodriguez at opensuse.org> wrote:
> On Mon, May 18, 2015 at 7:24 AM, 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.
>
> You could also
>
> posix_fadvise(fileno(f), 0, 0, POSIX_FADV_SEQUENTIAL);
> in the bits that load the unit file..the kernel is free to ignore that
> advice however.

This however.. won't be of any help, as the default readhead window is
128kb.. which is way bigger than any unit file.