Hi, Umut & David,
My project needs the Graphical desktop to display on monitor as fast as
possible, but I found lots of unrelated services( such as sound, network, ... )
are competing CPU even they are explicitly After graphical service. And this
competion delays the startup of graphical desktop process. So, my opinion is to
make graphical related programs runs first and the other unrelated services
only starts after graphical program finished startup. I will check "
StartupCPUShares=" this item and I hope it's helpful for me.
Thanks
-----Original Message-----
From: Umut Tezduyar Lindskog [mailto:u...@tezduyar.com]
Sent: Monday, November 17, 2014 17:51
To: Cao, XinX
Cc: systemd-devel@lists.freedesktop.org
Subject: Re: [systemd-devel] make systemd service takes cpu exclusively
Hi XinX
On Mon, Nov 17, 2014 at 9:40 AM, Cao, XinX <xinx....@intel.com> wrote:
> Hi, everybody,
>
>
>
> As we all know that currently systemd puts all the
> services into a run_queue, and lets them run together as possible as
> it can. However, this mechanism also brings in a problem, which means
> all the services will contend for CPU, and systemd is unable to make
> sure one service has priority ONE and only itself takes the CPU when this
> service is starting.
What exactly is the problem when they all want to get the CPU?
>
>
>
> For example, if we want to make sure a.service runs
> firstly , and all the other services runs after a.service is finished.
>
>
>
> So, does anybody know if systemd has this kind of
> mechanism? If not, can we create a way to do this and add this
> feature into systemd? Or is this idea possible? I think this is very usefull
> under some situations.
It really depends on your use case and what you consider with "a.service runs
first".
If you only want to start the service first, then you can always add
After=a.service directive to other services that are starting at the same time.
But this is pretty static information. You have to do this for every time you
change your priority service.
You could also prioritize a service by changing their StartupCPUShares= but
this is not truly stopping other services from being scheduled in. Maybe they
get the minimum CPU, but they still do.
Lennart has recently considered to change the startup queue to prioritized
startup queue where a prioritized service will be forked off before other
services -
http://lists.freedesktop.org/archives/systemd-devel/2014-October/024315.html.
Umut
>
>
>
> Thanks~
>
>
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