From: Joel Fernandes <[email protected]>

When a sched_ext server is loaded, tasks in the fair class are
automatically moved to the sched_ext class. Add support to modify the
ext server parameters similar to how the fair server parameters are
modified.

Re-use common code between ext and fair servers as needed.

v2: - use dl_se->dl_server to determine if dl_se is a DL server
      (Peter Zijlstra)
    - depend on CONFIG_SCHED_CLASS_EXT (Andrea Righi)

Reviewed-by: Juri Lelli <[email protected]>
Co-developed-by: Andrea Righi <[email protected]>
Signed-off-by: Andrea Righi <[email protected]>
Signed-off-by: Joel Fernandes <[email protected]>
---
 kernel/sched/debug.c | 157 ++++++++++++++++++++++++++++++++++++-------
 1 file changed, 133 insertions(+), 24 deletions(-)

diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index e71f6618c1a6a..9c2084d203df5 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -336,14 +336,16 @@ 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,
-                                      size_t cnt, loff_t *ppos, enum dl_param 
param)
+static ssize_t sched_server_write_common(struct file *filp, const char __user 
*ubuf,
+                                        size_t cnt, loff_t *ppos, enum 
dl_param param,
+                                        void *server)
 {
        long cpu = (long) ((struct seq_file *) filp->private_data)->private;
        struct rq *rq = cpu_rq(cpu);
+       struct sched_dl_entity *dl_se = (struct sched_dl_entity *)server;
        u64 runtime, period;
        int retval = 0;
        size_t err;
@@ -356,8 +358,8 @@ static ssize_t sched_fair_server_write(struct file *filp, 
const char __user *ubu
        scoped_guard (rq_lock_irqsave, rq) {
                bool is_active;
 
-               runtime  = rq->fair_server.dl_runtime;
-               period = rq->fair_server.dl_period;
+               runtime = dl_se->dl_runtime;
+               period = dl_se->dl_period;
 
                switch (param) {
                case DL_RUNTIME:
@@ -373,25 +375,25 @@ 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;
                }
 
-               is_active = dl_server_active(&rq->fair_server);
+               is_active = dl_server_active(dl_se);
                if (is_active) {
                        update_rq_clock(rq);
-                       dl_server_stop(&rq->fair_server);
+                       dl_server_stop(dl_se);
                }
 
-               retval = dl_server_apply_params(&rq->fair_server, runtime, 
period, 0);
+               retval = dl_server_apply_params(dl_se, runtime, period, 0);
 
                if (!runtime)
-                       printk_deferred("Fair server disabled in CPU %d, system 
may crash due to starvation.\n",
-                                       cpu_of(rq));
+                       printk_deferred("%s server disabled on CPU %d, system 
may crash due to starvation.\n",
+                                       server == &rq->fair_server ? "Fair" : 
"Ext", cpu_of(rq));
 
                if (is_active)
-                       dl_server_start(&rq->fair_server);
+                       dl_server_start(dl_se);
 
                if (retval < 0)
                        return retval;
@@ -401,36 +403,42 @@ static ssize_t sched_fair_server_write(struct file *filp, 
const char __user *ubu
        return cnt;
 }
 
-static size_t sched_fair_server_show(struct seq_file *m, void *v, enum 
dl_param param)
+static size_t sched_server_show_common(struct seq_file *m, void *v, enum 
dl_param param,
+                                      void *server)
 {
-       unsigned long cpu = (unsigned long) m->private;
-       struct rq *rq = cpu_rq(cpu);
+       struct sched_dl_entity *dl_se = (struct sched_dl_entity *)server;
        u64 value;
 
        switch (param) {
        case DL_RUNTIME:
-               value = rq->fair_server.dl_runtime;
+               value = dl_se->dl_runtime;
                break;
        case DL_PERIOD:
-               value = rq->fair_server.dl_period;
+               value = dl_se->dl_period;
                break;
        }
 
        seq_printf(m, "%llu\n", value);
        return 0;
-
 }
 
 static ssize_t
 sched_fair_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);
+       long cpu = (long) ((struct seq_file *) filp->private_data)->private;
+       struct rq *rq = cpu_rq(cpu);
+
+       return sched_server_write_common(filp, ubuf, cnt, ppos, DL_RUNTIME,
+                                       &rq->fair_server);
 }
 
 static int sched_fair_server_runtime_show(struct seq_file *m, void *v)
 {
-       return sched_fair_server_show(m, v, DL_RUNTIME);
+       unsigned long cpu = (unsigned long) m->private;
+       struct rq *rq = cpu_rq(cpu);
+
+       return sched_server_show_common(m, v, DL_RUNTIME, &rq->fair_server);
 }
 
 static int sched_fair_server_runtime_open(struct inode *inode, struct file 
*filp)
@@ -446,16 +454,57 @@ static const struct file_operations 
fair_server_runtime_fops = {
        .release        = single_release,
 };
 
+#ifdef CONFIG_SCHED_CLASS_EXT
+static ssize_t
+sched_ext_server_runtime_write(struct file *filp, const char __user *ubuf,
+                              size_t cnt, loff_t *ppos)
+{
+       long cpu = (long) ((struct seq_file *) filp->private_data)->private;
+       struct rq *rq = cpu_rq(cpu);
+
+       return sched_server_write_common(filp, ubuf, cnt, ppos, DL_RUNTIME,
+                                       &rq->ext_server);
+}
+
+static int sched_ext_server_runtime_show(struct seq_file *m, void *v)
+{
+       unsigned long cpu = (unsigned long) m->private;
+       struct rq *rq = cpu_rq(cpu);
+
+       return sched_server_show_common(m, v, DL_RUNTIME, &rq->ext_server);
+}
+
+static int sched_ext_server_runtime_open(struct inode *inode, struct file 
*filp)
+{
+       return single_open(filp, sched_ext_server_runtime_show, 
inode->i_private);
+}
+
+static const struct file_operations ext_server_runtime_fops = {
+       .open           = sched_ext_server_runtime_open,
+       .write          = sched_ext_server_runtime_write,
+       .read           = seq_read,
+       .llseek         = seq_lseek,
+       .release        = single_release,
+};
+#endif /* CONFIG_SCHED_CLASS_EXT */
+
 static ssize_t
 sched_fair_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);
+       long cpu = (long) ((struct seq_file *) filp->private_data)->private;
+       struct rq *rq = cpu_rq(cpu);
+
+       return sched_server_write_common(filp, ubuf, cnt, ppos, DL_PERIOD,
+                                       &rq->fair_server);
 }
 
 static int sched_fair_server_period_show(struct seq_file *m, void *v)
 {
-       return sched_fair_server_show(m, v, DL_PERIOD);
+       unsigned long cpu = (unsigned long) m->private;
+       struct rq *rq = cpu_rq(cpu);
+
+       return sched_server_show_common(m, v, DL_PERIOD, &rq->fair_server);
 }
 
 static int sched_fair_server_period_open(struct inode *inode, struct file 
*filp)
@@ -471,6 +520,40 @@ static const struct file_operations 
fair_server_period_fops = {
        .release        = single_release,
 };
 
+#ifdef CONFIG_SCHED_CLASS_EXT
+static ssize_t
+sched_ext_server_period_write(struct file *filp, const char __user *ubuf,
+                             size_t cnt, loff_t *ppos)
+{
+       long cpu = (long) ((struct seq_file *) filp->private_data)->private;
+       struct rq *rq = cpu_rq(cpu);
+
+       return sched_server_write_common(filp, ubuf, cnt, ppos, DL_PERIOD,
+                                       &rq->ext_server);
+}
+
+static int sched_ext_server_period_show(struct seq_file *m, void *v)
+{
+       unsigned long cpu = (unsigned long) m->private;
+       struct rq *rq = cpu_rq(cpu);
+
+       return sched_server_show_common(m, v, DL_PERIOD, &rq->ext_server);
+}
+
+static int sched_ext_server_period_open(struct inode *inode, struct file *filp)
+{
+       return single_open(filp, sched_ext_server_period_show, 
inode->i_private);
+}
+
+static const struct file_operations ext_server_period_fops = {
+       .open           = sched_ext_server_period_open,
+       .write          = sched_ext_server_period_write,
+       .read           = seq_read,
+       .llseek         = seq_lseek,
+       .release        = single_release,
+};
+#endif /* CONFIG_SCHED_CLASS_EXT */
+
 static struct dentry *debugfs_sched;
 
 static void debugfs_fair_server_init(void)
@@ -494,6 +577,29 @@ static void debugfs_fair_server_init(void)
        }
 }
 
+#ifdef CONFIG_SCHED_CLASS_EXT
+static void debugfs_ext_server_init(void)
+{
+       struct dentry *d_ext;
+       unsigned long cpu;
+
+       d_ext = debugfs_create_dir("ext_server", debugfs_sched);
+       if (!d_ext)
+               return;
+
+       for_each_possible_cpu(cpu) {
+               struct dentry *d_cpu;
+               char buf[32];
+
+               snprintf(buf, sizeof(buf), "cpu%lu", cpu);
+               d_cpu = debugfs_create_dir(buf, d_ext);
+
+               debugfs_create_file("runtime", 0644, d_cpu, (void *) cpu, 
&ext_server_runtime_fops);
+               debugfs_create_file("period", 0644, d_cpu, (void *) cpu, 
&ext_server_period_fops);
+       }
+}
+#endif /* CONFIG_SCHED_CLASS_EXT */
+
 static __init int sched_init_debug(void)
 {
        struct dentry __maybe_unused *numa;
@@ -532,6 +638,9 @@ static __init int sched_init_debug(void)
        debugfs_create_file("debug", 0444, debugfs_sched, NULL, 
&sched_debug_fops);
 
        debugfs_fair_server_init();
+#ifdef CONFIG_SCHED_CLASS_EXT
+       debugfs_ext_server_init();
+#endif
 
        return 0;
 }
-- 
2.51.2


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