[systemd-devel] set rr scheduler failed with cpushares

[Umut Tezduyar Lindskog]

Hi,


On Tue, Dec 2, 2014 at 7:12 PM, Lennart Poettering
<lennart at poettering.net> wrote:
> On Mon, 17.11.14 23:46, WaLyong Cho (walyong.cho at samsung.com) wrote:
>
>> Hello,
>>
>> I'd made two different services. One has *CPUSchedulingPolicy=rr* and
>> the others has *CPUShares=*.
>>
>> Could anyone help me?
>
> If CPUShares= is set this has the effect that the service and all
> services in the same slice will be have the "cpu" cgroup controller
> turned on. Unfortunately this has the effect that RT scheduling will
> be unavailable then, unless an explicit RT budget is configured for
> that specific cgroup. This is something systemd cannot be used for
> nicely however, as we don't expose high-level controls for the RT
> budget.
>
> The RT budget is configured in the cpu.rt_runtime_us and
> cpu.rt_period_us cgroup attributes. You can write to them from
> ExecStartPre= for example using the %c specified.

Wouldn't it be against the idea of "access to control groups should go
through systemd"?

Is this something you are recommending until we start exposing RT
parts of the cgroups, or?

Umut

>
> Another option is to simply disable CONFIG_RT_GROUP_SCHED in the
> kernel, if you don't need it anyway.
>
> Lennart
>
> --
> Lennart Poettering, Red Hat
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