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Message-ID: <177011752053.2495410.7129705261433888025.tip-bot2@tip-bot2>
Date: Tue, 03 Feb 2026 11:18:40 -0000
From: "tip-bot2 for Joel Fernandes" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Andrea Righi <arighi@...dia.com>, Joel Fernandes <joelagnelf@...dia.com>,
"Peter Zijlstra (Intel)" <peterz@...radead.org>,
Juri Lelli <juri.lelli@...hat.com>,
Christian Loehle <christian.loehle@....com>, x86@...nel.org,
linux-kernel@...r.kernel.org
Subject:
[tip: sched/core] sched/debug: Add support to change sched_ext server params
The following commit has been merged into the sched/core branch of tip:
Commit-ID: 76d12132ba459ab929cb66eb2030c666aacdb69a
Gitweb: https://git.kernel.org/tip/76d12132ba459ab929cb66eb2030c666aacdb69a
Author: Joel Fernandes <joelagnelf@...dia.com>
AuthorDate: Mon, 26 Jan 2026 10:59:03 +01:00
Committer: Peter Zijlstra <peterz@...radead.org>
CommitterDate: Tue, 03 Feb 2026 12:04:17 +01:00
sched/debug: Add support to change sched_ext server params
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.
Co-developed-by: Andrea Righi <arighi@...dia.com>
Signed-off-by: Andrea Righi <arighi@...dia.com>
Signed-off-by: Joel Fernandes <joelagnelf@...dia.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Juri Lelli <juri.lelli@...hat.com>
Tested-by: Christian Loehle <christian.loehle@....com>
Link: https://patch.msgid.link/20260126100050.3854740-6-arighi@nvidia.com
---
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 41e3895..59e650f 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -330,14 +330,16 @@ 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;
@@ -350,8 +352,8 @@ 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:
@@ -367,25 +369,25 @@ 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 in CPU %d, system may crash due to starvation.\n",
+ server == &rq->fair_server ? "Fair" : "Ext", cpu_of(rq));
if (is_active && runtime)
- dl_server_start(&rq->fair_server);
+ dl_server_start(dl_se);
if (retval < 0)
return retval;
@@ -395,36 +397,42 @@ 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)
@@ -440,16 +448,57 @@ 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)
@@ -465,6 +514,40 @@ 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)
@@ -488,6 +571,29 @@ 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;
@@ -526,6 +632,9 @@ 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;
}
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