Re: [PATCH V7 9/9] sched/rt: Remove default bandwidth control
From: Michal Koutný
Date: Wed Nov 27 2024 - 05:56:48 EST
Hello.
(I'm replying now as I installed v6.12 and this message has the
context.)
On Mon, May 27, 2024 at 02:06:55PM GMT, Daniel Bristot de Oliveira <bristot@xxxxxxxxxx> wrote:
> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
> index 0dbb42cf7fe6..7df8179bfa08 100644
> --- a/kernel/sched/deadline.c
> +++ b/kernel/sched/deadline.c
> @@ -1554,6 +1554,7 @@ static void update_curr_dl_se(struct rq *rq, struct sched_dl_entity *dl_se, s64
> if (dl_se == &rq->fair_server)
> return;
>
> +#ifdef CONFIG_RT_GROUP_SCHED
> /*
> * Because -- for now -- we share the rt bandwidth, we need to
> * account our runtime there too, otherwise actual rt tasks
> @@ -1578,6 +1579,7 @@ static void update_curr_dl_se(struct rq *rq, struct sched_dl_entity *dl_se, s64
> rt_rq->rt_time += delta_exec;
> raw_spin_unlock(&rt_rq->rt_runtime_lock);
> }
> +#endif
> }
>
> /*
> @@ -1632,8 +1634,7 @@ void dl_server_start(struct sched_dl_entity *dl_se)
> * this before getting generic.
> */
> if (!dl_server(dl_se)) {
> - /* Disabled */
> - u64 runtime = 0;
> + u64 runtime = 50 * NSEC_PER_MSEC;
> u64 period = 1000 * NSEC_PER_MSEC;
>
> dl_server_apply_params(dl_se, runtime, period, 1);
The global_rt_runtime() also applies to deadline class when CPU's DL
bandwidth is init'd in init_dl_rq_bw_ratio().
The default DL bandwidth is thus is 95%. The fair server is given 5%.
Is that 5% of those 95%?
Or is it meant to be complementary? (Perhaps not as I can configure
rt_runtime_us/rt_period_us > 95% without an error. But then I don't
understand what the global rt_runtime_us (w/out CONFIG_RT_GROUP_SCHED)
configures.)
Thanks for some hints,
Michal
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