Re: [PATCH v2] sched/deadline: fix runtime accounting in documentation

[Mathieu Poirier]

Hi Claudio,

On 14 November 2017 at 04:19, Claudio Scordino <claudio@xxxxxxxxxxxxxxx> wrote:
> Signed-off-by: Claudio Scordino <claudio@xxxxxxxxxxxxxxx>
> Signed-off-by: Luca Abeni <luca.abeni@xxxxxxxxxxxxxxx>
> Acked-by: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
> CC: Jonathan Corbet <corbet@xxxxxxx>
> CC: "Peter Zijlstra (Intel)" <peterz@xxxxxxxxxxxxx>
> CC: Ingo Molnar <mingo@xxxxxxxxxx>
> CC: linux-doc@xxxxxxxxxxxxxxx
> Cc: Tommaso Cucinotta <tommaso.cucinotta@xxxxxxxx>
> Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
> ---

Please add a short description for your change, even if it is trivial.


>  Documentation/scheduler/sched-deadline.txt | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/scheduler/sched-deadline.txt b/Documentation/scheduler/sched-deadline.txt
> index e89e36e..8ce78f8 100644
> --- a/Documentation/scheduler/sched-deadline.txt
> +++ b/Documentation/scheduler/sched-deadline.txt
> @@ -204,10 +204,17 @@ CONTENTS
>   It does so by decrementing the runtime of the executing task Ti at a pace equal
>   to
>
> -           dq = -max{ Ui, (1 - Uinact) } dt
> +           dq = -max{ Ui / Umax, (1 - Uinact - Uextra) } dt
>
> - where Uinact is the inactive utilization, computed as (this_bq - running_bw),
> - and Ui is the bandwidth of task Ti.
> + where:
> +
> +  - Ui is the bandwidth of task Ti;
> +  - Umax is the maximum reclaimable utilization (subjected to RT throttling
> +    limits);
> +  - Uinact is the (per runqueue) inactive utilization, computed as
> +    (this_bq - running_bw);
> +  - Uextra is the (per runqueue) extra reclaimable utilization
> +    (subjected to RT throttling limits).

I think there would be value in defining 'dq' and 'dt'.  That way
people know exactly what they are and it leaves no room for
interpretation.

Thanks,
Mathieu

>
>
>   Let's now see a trivial example of two deadline tasks with runtime equal
> --
> 2.7.4
>