[PATCH v7 06/23] sched: Add CONFIG_SCHED_PROXY_EXEC & boot argument to enable/disable

John Stultz
2023-12-20T00:19:14Z

Add a CONFIG_SCHED_PROXY_EXEC option, along with a boot argument
sched_prox_exec= that can be used to disable the feature at boot
time if CONFIG_SCHED_PROXY_EXEC was enabled.

Cc: Joel Fernandes <joelaf@google.com>
Cc: Qais Yousef <qyousef@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Zimuzo Ezeozue <zezeozue@google.com>
Cc: Youssef Esmat <youssefesmat@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Metin Kaya <Metin.Kaya@arm.com>
Cc: Xuewen Yan <xuewen.yan94@gmail.com>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-team@android.com
Signed-off-by: John Stultz <jstultz@google.com>
---
v7:
* Switch to CONFIG_SCHED_PROXY_EXEC/sched_proxy_exec= as
suggested by Metin Kaya.
* Switch boot arg from =disable/enable to use kstrtobool(),
which supports =yes|no|1|0|true|false|on|off, as also
suggested by Metin Kaya, and print a message when a boot
argument is used.
---
.../admin-guide/kernel-parameters.txt | 5 ++++
include/linux/sched.h | 13 +++++++++
init/Kconfig | 7 +++++
kernel/sched/core.c | 29 +++++++++++++++++++
4 files changed, 54 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 65731b060e3f..cc64393b913f 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5714,6 +5714,11 @@
sa1100ir [NET]
See drivers/net/irda/sa1100_ir.c.

+ sched_proxy_exec= [KNL]
+ Enables or disables "proxy execution" style
+ solution to mutex based priority inversion.
+ Format: <bool>
+
sched_verbose [KNL] Enables verbose scheduler debug messages.

schedstats= [KNL,X86] Enable or disable scheduled statistics.
diff --git a/include/linux/sched.h b/include/linux/sched.h
index bfe8670f99a1..880af1c3097d 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1566,6 +1566,19 @@ struct task_struct {
*/
};

+#ifdef CONFIG_SCHED_PROXY_EXEC
+DECLARE_STATIC_KEY_TRUE(__sched_proxy_exec);
+static inline bool sched_proxy_exec(void)
+{
+ return static_branch_likely(&__sched_proxy_exec);
+}
+#else
+static inline bool sched_proxy_exec(void)
+{
+ return false;
+}
+#endif
+
static inline struct pid *task_pid(struct task_struct *task)
{
return task->thread_pid;
diff --git a/init/Kconfig b/init/Kconfig
index 9ffb103fc927..c5a759b6366a 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -908,6 +908,13 @@ config NUMA_BALANCING_DEFAULT_ENABLED
If set, automatic NUMA balancing will be enabled if running on a NUMA
machine.

+config SCHED_PROXY_EXEC
+ bool "Proxy Execution"
+ default n
+ help
+ This option enables proxy execution, a mechanism for mutex owning
+ tasks to inherit the scheduling context of higher priority waiters.
+
menuconfig CGROUPS
bool "Control Group support"
select KERNFS
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 4e46189d545d..e06558fb08aa 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -117,6 +117,35 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(sched_compute_energy_tp);

DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);

+#ifdef CONFIG_SCHED_PROXY_EXEC
+DEFINE_STATIC_KEY_TRUE(__sched_proxy_exec);
+static int __init setup_proxy_exec(char *str)
+{
+ bool proxy_enable;
+
+ if (kstrtobool(str, &proxy_enable)) {
+ pr_warn("Unable to parse sched_proxy_exec=\n");
+ return 0;
+ }
+
+ if (proxy_enable) {
+ pr_info("sched_proxy_exec enabled via boot arg\n");
+ static_branch_enable(&__sched_proxy_exec);
+ } else {
+ pr_info("sched_proxy_exec disabled via boot arg\n");
+ static_branch_disable(&__sched_proxy_exec);
+ }
+ return 1;
+}
+#else
+static int __init setup_proxy_exec(char *str)
+{
+ pr_warn("CONFIG_SCHED_PROXY_EXEC=n, so it cannot be enabled or disabled at boottime\n");
+ return 0;
+}
+#endif
+__setup("sched_proxy_exec=", setup_proxy_exec);
+
#ifdef CONFIG_SCHED_DEBUG
/*
* Debugging: various feature bits
--
2.43.0.472.g3155946c3a-goog