1 files changed, 31 insertions, 3 deletions

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 652a364e9e4c..1a9b28dd0961 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -143,6 +143,32 @@ static struct scx_dump_data scx_dump_data = {
 /* /sys/kernel/sched_ext interface */
 static struct kset *scx_kset;
 
+/*
+ * Parameters that can be adjusted through /sys/module/sched_ext/parameters.
+ * There usually is no reason to modify these as normal scheduler operation
+ * shouldn't be affected by them. The knobs are primarily for debugging.
+ */
+static u64 scx_slice_dfl = SCX_SLICE_DFL;
+static unsigned int scx_slice_bypass_us = SCX_SLICE_BYPASS / NSEC_PER_USEC;
+
+static int set_slice_us(const char *val, const struct kernel_param *kp)
+{
+	return param_set_uint_minmax(val, kp, 100, 100 * USEC_PER_MSEC);
+}
+
+static const struct kernel_param_ops slice_us_param_ops = {
+	.set = set_slice_us,
+	.get = param_get_uint,
+};
+
+#undef MODULE_PARAM_PREFIX
+#define MODULE_PARAM_PREFIX	"sched_ext."
+
+module_param_cb(slice_bypass_us, &slice_us_param_ops, &scx_slice_bypass_us, 0600);
+MODULE_PARM_DESC(slice_bypass_us, "bypass slice in microseconds, applied on [un]load (100us to 100ms)");
+
+#undef MODULE_PARAM_PREFIX
+
 #define CREATE_TRACE_POINTS
 #include <trace/events/sched_ext.h>
 
@@ -919,7 +945,7 @@ static void dsq_mod_nr(struct scx_dispatch_q *dsq, s32 delta)
 
 static void refill_task_slice_dfl(struct scx_sched *sch, struct task_struct *p)
 {
-	p->scx.slice = SCX_SLICE_DFL;
+	p->scx.slice = READ_ONCE(scx_slice_dfl);
 	__scx_add_event(sch, SCX_EV_REFILL_SLICE_DFL, 1);
 }
 
@@ -2896,7 +2922,7 @@ void init_scx_entity(struct sched_ext_entity *scx)
 	INIT_LIST_HEAD(&scx->runnable_node);
 	scx->runnable_at = jiffies;
 	scx->ddsp_dsq_id = SCX_DSQ_INVALID;
-	scx->slice = SCX_SLICE_DFL;
+	scx->slice = READ_ONCE(scx_slice_dfl);
 }
 
 void scx_pre_fork(struct task_struct *p)
@@ -3774,6 +3800,7 @@ static void scx_bypass(bool bypass)
 		WARN_ON_ONCE(scx_bypass_depth <= 0);
 		if (scx_bypass_depth != 1)
 			goto unlock;
+		WRITE_ONCE(scx_slice_dfl, scx_slice_bypass_us * NSEC_PER_USEC);
 		bypass_timestamp = ktime_get_ns();
 		if (sch)
 			scx_add_event(sch, SCX_EV_BYPASS_ACTIVATE, 1);
@@ -3782,6 +3809,7 @@ static void scx_bypass(bool bypass)
 		WARN_ON_ONCE(scx_bypass_depth < 0);
 		if (scx_bypass_depth != 0)
 			goto unlock;
+		WRITE_ONCE(scx_slice_dfl, SCX_SLICE_DFL);
 		if (sch)
 			scx_add_event(sch, SCX_EV_BYPASS_DURATION,
 				      ktime_get_ns() - bypass_timestamp);
@@ -4780,7 +4808,7 @@ static int scx_enable(struct sched_ext_ops *ops, struct bpf_link *link)
 			queue_flags |= DEQUEUE_CLASS;
 
 		scoped_guard (sched_change, p, queue_flags) {
-			p->scx.slice = SCX_SLICE_DFL;
+			p->scx.slice = READ_ONCE(scx_slice_dfl);
 			p->sched_class = new_class;
 		}
 	}