On Thu, Nov 06, 2025 at 08:13:39AM +0100, Juri Lelli wrote: > Hi, > > On 29/10/25 20:08, Andrea Righi wrote: > > From: Joel Fernandes <[email protected]> > > > > Currently the DL server interface for applying parameters checks > > CFS-internals to identify if the server is active. This is error-prone > > and makes it difficult when adding new servers in the future. > > > > Fix it, by using dl_server_active() which is also used by the DL server > > code to determine if the DL server was started. > > > > Acked-by: Tejun Heo <[email protected]> > > Reviewed-by: Juri Lelli <[email protected]> > > Reviewed-by: Andrea Righi <[email protected]> > > Signed-off-by: Joel Fernandes <[email protected]> > > --- > > kernel/sched/debug.c | 11 ++++++++--- > > 1 file changed, 8 insertions(+), 3 deletions(-) > > > > diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c > > index 6cf9be6eea49a..e71f6618c1a6a 100644 > > --- a/kernel/sched/debug.c > > +++ b/kernel/sched/debug.c > > @@ -354,6 +354,8 @@ static ssize_t sched_fair_server_write(struct file > > *filp, const char __user *ubu > > return err; > > > > scoped_guard (rq_lock_irqsave, rq) { > > + bool is_active; > > + > > runtime = rq->fair_server.dl_runtime; > > period = rq->fair_server.dl_period; > > > > @@ -376,8 +378,11 @@ static ssize_t sched_fair_server_write(struct file > > *filp, const char __user *ubu > > return -EINVAL; > > } > > > > - update_rq_clock(rq); > > - dl_server_stop(&rq->fair_server); > > + is_active = dl_server_active(&rq->fair_server); > > + if (is_active) { > > + update_rq_clock(rq); > > + dl_server_stop(&rq->fair_server); > > + } > > > > retval = dl_server_apply_params(&rq->fair_server, runtime, > > period, 0); > > > > @@ -385,7 +390,7 @@ static ssize_t sched_fair_server_write(struct file > > *filp, const char __user *ubu > > printk_deferred("Fair server disabled in CPU %d, system > > may crash due to starvation.\n", > > cpu_of(rq)); > > > > - if (rq->cfs.h_nr_queued) > > + if (is_active) > > dl_server_start(&rq->fair_server); > > Something that I noticed while reviewing this series is that we still > start back a server even if the user put its runtime to zero (disabling > it) and I don't think we want to do that. It's not of course related to > this change or this series per-se, but something we probably want to fix > independently.
Should we just call dl_server_remove_params() when runtime is zero? Thanks, -Andrea
