[PATCH RFC 6/8] sched/debug: Add support to change sched_ext server params

[Joel Fernandes <joelagnelf@nvidia.com>]

When a sched_ext server is loaded, tasks in CFS are converted to run in
sched_ext class. Modify the ext server parameters as well along with the
fair ones.

Re-use the existing interface to modify both ext and fair servers to
keep number of interfaces less (as it is, we have a per-cpu interface).

Reviewed-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
---
 kernel/sched/debug.c | 91 ++++++++++++++++++++++++++------------------
 1 file changed, 54 insertions(+), 37 deletions(-)

diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 83cb695d6d46..218b3e239128 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -339,17 +339,18 @@ enum dl_param {
 	DL_PERIOD,
 };
 
-static unsigned long fair_server_period_max = (1UL << 22) * NSEC_PER_USEC; /* ~4 seconds */
-static unsigned long fair_server_period_min = (100) * NSEC_PER_USEC;     /* 100 us */
+static unsigned long dl_server_period_max = (1UL << 22) * NSEC_PER_USEC; /* ~4 seconds */
+static unsigned long dl_server_period_min = (100) * NSEC_PER_USEC;     /* 100 us */
 
-static ssize_t sched_fair_server_write(struct file *filp, const char __user *ubuf,
+static ssize_t sched_dl_server_write(struct file *filp, const char __user *ubuf,
 				       size_t cnt, loff_t *ppos, enum dl_param param)
 {
 	long cpu = (long) ((struct seq_file *) filp->private_data)->private;
 	struct rq *rq = cpu_rq(cpu);
-	bool was_active = false;
+	bool was_active_fair = false;
+	bool was_active_ext = false;
+	int retval = 0, retval2 = 0;
 	u64 runtime, period;
-	int retval = 0;
 	size_t err;
 	u64 value;
 
@@ -375,41 +376,57 @@ static ssize_t sched_fair_server_write(struct file *filp, const char __user *ubu
 		}
 
 		if (runtime > period ||
-		    period > fair_server_period_max ||
-		    period < fair_server_period_min) {
+		    period > dl_server_period_max ||
+		    period < dl_server_period_min) {
 			return  -EINVAL;
 		}
 
 		if (dl_server_active(&rq->fair_server)) {
-			was_active = true;
+			was_active_fair = true;
 			update_rq_clock(rq);
 			dl_server_stop(&rq->fair_server);
 		}
 
+		if (dl_server_active(&rq->ext_server)) {
+			was_active_ext = true;
+			update_rq_clock(rq);
+			dl_server_stop(&rq->ext_server);
+		}
+
 		retval = dl_server_apply_params(&rq->fair_server, runtime, period, 0);
+		retval2 = dl_server_apply_params(&rq->ext_server, runtime, period, 0);
 
 		if (!runtime)
-			printk_deferred("Fair server disabled in CPU %d, system may crash due to starvation.\n",
+			printk_deferred("Deadline servers are disabled on CPU %d, system may crash due to starvation.\n",
 					cpu_of(rq));
 
-		if (was_active)
+		if (was_active_fair)
 			dl_server_start(&rq->fair_server);
 
+		if (was_active_ext)
+			dl_server_start(&rq->ext_server);
+
 		if (retval < 0)
 			return retval;
+		if (retval2 < 0)
+			return retval2;
 	}
 
 	*ppos += cnt;
 	return cnt;
 }
 
-static size_t sched_fair_server_show(struct seq_file *m, void *v, enum dl_param param)
+static size_t sched_dl_server_show(struct seq_file *m, void *v, enum dl_param param)
 {
 	unsigned long cpu = (unsigned long) m->private;
 	struct rq *rq = cpu_rq(cpu);
 	u64 value;
 
 	switch (param) {
+	/*
+	 * The params for fair server and ext server as set via debugfs
+	 * are the same, so we can just use one of them
+	 */
 	case DL_RUNTIME:
 		value = rq->fair_server.dl_runtime;
 		break;
@@ -424,50 +441,50 @@ static size_t sched_fair_server_show(struct seq_file *m, void *v, enum dl_param
 }
 
 static ssize_t
-sched_fair_server_runtime_write(struct file *filp, const char __user *ubuf,
+sched_dl_server_runtime_write(struct file *filp, const char __user *ubuf,
 				size_t cnt, loff_t *ppos)
 {
-	return sched_fair_server_write(filp, ubuf, cnt, ppos, DL_RUNTIME);
+	return sched_dl_server_write(filp, ubuf, cnt, ppos, DL_RUNTIME);
 }
 
-static int sched_fair_server_runtime_show(struct seq_file *m, void *v)
+static int sched_dl_server_runtime_show(struct seq_file *m, void *v)
 {
-	return sched_fair_server_show(m, v, DL_RUNTIME);
+	return sched_dl_server_show(m, v, DL_RUNTIME);
 }
 
-static int sched_fair_server_runtime_open(struct inode *inode, struct file *filp)
+static int sched_dl_server_runtime_open(struct inode *inode, struct file *filp)
 {
-	return single_open(filp, sched_fair_server_runtime_show, inode->i_private);
+	return single_open(filp, sched_dl_server_runtime_show, inode->i_private);
 }
 
-static const struct file_operations fair_server_runtime_fops = {
-	.open		= sched_fair_server_runtime_open,
-	.write		= sched_fair_server_runtime_write,
+static const struct file_operations dl_server_runtime_fops = {
+	.open		= sched_dl_server_runtime_open,
+	.write		= sched_dl_server_runtime_write,
 	.read		= seq_read,
 	.llseek		= seq_lseek,
 	.release	= single_release,
 };
 
 static ssize_t
-sched_fair_server_period_write(struct file *filp, const char __user *ubuf,
+sched_dl_server_period_write(struct file *filp, const char __user *ubuf,
 			       size_t cnt, loff_t *ppos)
 {
-	return sched_fair_server_write(filp, ubuf, cnt, ppos, DL_PERIOD);
+	return sched_dl_server_write(filp, ubuf, cnt, ppos, DL_PERIOD);
 }
 
-static int sched_fair_server_period_show(struct seq_file *m, void *v)
+static int sched_dl_server_period_show(struct seq_file *m, void *v)
 {
-	return sched_fair_server_show(m, v, DL_PERIOD);
+	return sched_dl_server_show(m, v, DL_PERIOD);
 }
 
-static int sched_fair_server_period_open(struct inode *inode, struct file *filp)
+static int sched_dl_server_period_open(struct inode *inode, struct file *filp)
 {
-	return single_open(filp, sched_fair_server_period_show, inode->i_private);
+	return single_open(filp, sched_dl_server_period_show, inode->i_private);
 }
 
-static const struct file_operations fair_server_period_fops = {
-	.open		= sched_fair_server_period_open,
-	.write		= sched_fair_server_period_write,
+static const struct file_operations dl_server_period_fops = {
+	.open		= sched_dl_server_period_open,
+	.write		= sched_dl_server_period_write,
 	.read		= seq_read,
 	.llseek		= seq_lseek,
 	.release	= single_release,
@@ -475,13 +492,13 @@ static const struct file_operations fair_server_period_fops = {
 
 static struct dentry *debugfs_sched;
 
-static void debugfs_fair_server_init(void)
+static void debugfs_dl_server_init(void)
 {
-	struct dentry *d_fair;
+	struct dentry *d_server;
 	unsigned long cpu;
 
-	d_fair = debugfs_create_dir("fair_server", debugfs_sched);
-	if (!d_fair)
+	d_server = debugfs_create_dir("dl_server", debugfs_sched);
+	if (!d_server)
 		return;
 
 	for_each_possible_cpu(cpu) {
@@ -489,10 +506,10 @@ static void debugfs_fair_server_init(void)
 		char buf[32];
 
 		snprintf(buf, sizeof(buf), "cpu%lu", cpu);
-		d_cpu = debugfs_create_dir(buf, d_fair);
+		d_cpu = debugfs_create_dir(buf, d_server);
 
-		debugfs_create_file("runtime", 0644, d_cpu, (void *) cpu, &fair_server_runtime_fops);
-		debugfs_create_file("period", 0644, d_cpu, (void *) cpu, &fair_server_period_fops);
+		debugfs_create_file("runtime", 0644, d_cpu, (void *) cpu, &dl_server_runtime_fops);
+		debugfs_create_file("period", 0644, d_cpu, (void *) cpu, &dl_server_period_fops);
 	}
 }
 
@@ -535,7 +552,7 @@ static __init int sched_init_debug(void)
 
 	debugfs_create_file("debug", 0444, debugfs_sched, NULL, &sched_debug_fops);
 
-	debugfs_fair_server_init();
+	debugfs_dl_server_init();
 
 	return 0;
 }
-- 
2.43.0