sched/deadline: Remove the sysctl_sched_dl knobs

Remove the deadline specific sysctls for now. The problem with them is
that the interaction with the exisiting rt knobs is nearly impossible
to get right.

The current (as per before this patch) situation is that the rt and dl
bandwidth is completely separate and we enforce rt+dl < 100%. This is
undesirable because this means that the rt default of 95% leaves us
hardly any room, even though dl tasks are saver than rt tasks.

Another proposed solution was (a discarted patch) to have the dl
bandwidth be a fraction of the rt bandwidth. This is highly
confusing imo.

Furthermore neither proposal is consistent with the situation we
actually want; which is rt tasks ran from a dl server. In which case
the rt bandwidth is a direct subset of dl.

So whichever way we go, the introduction of dl controls at this point
is painful. Therefore remove them and instead share the rt budget.

This means that for now the rt knobs are used for dl admission control
and the dl runtime is accounted against the rt runtime. I realise that
this isn't entirely desirable either; but whatever we do we appear to
need to change the interface later, so better have a small interface
for now.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-zpyqbqds1r0vyxtxza1e7rdc@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 0 insertions, 13 deletions

diff --git a/include/linux/sched/sysctl.h b/include/linux/sched/sysctl.h
index 8070a83dbedc..31e0193cb0c5 100644
--- a/include/linux/sched/sysctl.h
+++ b/include/linux/sched/sysctl.h
@@ -81,15 +81,6 @@ static inline unsigned int get_sysctl_timer_migration(void)
 extern unsigned int sysctl_sched_rt_period;
 extern int sysctl_sched_rt_runtime;
 
-/*
- *  control SCHED_DEADLINE reservations:
- *
- *  /proc/sys/kernel/sched_dl_period_us
- *  /proc/sys/kernel/sched_dl_runtime_us
- */
-extern unsigned int sysctl_sched_dl_period;
-extern int sysctl_sched_dl_runtime;
-
 #ifdef CONFIG_CFS_BANDWIDTH
 extern unsigned int sysctl_sched_cfs_bandwidth_slice;
 #endif
@@ -108,8 +99,4 @@ extern int sched_rt_handler(struct ctl_table *table, int write,
 		void __user *buffer, size_t *lenp,
 		loff_t *ppos);
 
-int sched_dl_handler(struct ctl_table *table, int write,
-		void __user *buffer, size_t *lenp,
-		loff_t *ppos);
-
 #endif /* _SCHED_SYSCTL_H */