From: "Peter Zijlstra (Intel)" <pet...@infradead.org>
Support the preempt= boot option and patch the static call sites
accordingly.
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Mel Gorman <mgor...@suse.de>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: Michal Hocko <mho...@kernel.org>
Cc: Paul E. McKenney <paul...@kernel.org>
[remove the mad scientist experiments]
Signed-off-by: Frederic Weisbecker <frede...@kernel.org>
---
kernel/sched/core.c | 67 ++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 66 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 6715caa17ea7..84ac05d2df3a 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -12,6 +12,7 @@
#include "sched.h"
+#include <linux/entry-common.h>
#include <linux/nospec.h>
#include <linux/kcov.h>
@@ -4772,9 +4773,73 @@ DEFINE_STATIC_CALL(preempt_schedule_notrace,
__preempt_schedule_notrace_func());
EXPORT_STATIC_CALL(preempt_schedule_notrace);
#endif
-
#endif /* CONFIG_PREEMPTION */
+#ifdef CONFIG_PREEMPT_DYNAMIC
+
+/*
+ * SC:cond_resched
+ * SC:might_resched
+ * SC:preempt_schedule
+ * SC:preempt_schedule_notrace
+ * SC:irqentry_exit_cond_resched
+ *
+ *
+ * NONE:
+ * cond_resched <- __cond_resched
+ * might_resched <- RET0
+ * preempt_schedule <- NOP
+ * preempt_schedule_notrace <- NOP
+ * irqentry_exit_cond_resched <- NOP
+ *
+ * VOLUNTARY:
+ * cond_resched <- __cond_resched
+ * might_resched <- __cond_resched
+ * preempt_schedule <- NOP
+ * preempt_schedule_notrace <- NOP
+ * irqentry_exit_cond_resched <- NOP
+ *
+ * FULL:
+ * cond_resched <- RET0
+ * might_resched <- RET0
+ * preempt_schedule <- preempt_schedule
+ * preempt_schedule_notrace <- preempt_schedule_notrace
+ * irqentry_exit_cond_resched <- irqentry_exit_cond_resched
+ */
+static int __init setup_preempt_mode(char *str)
+{
+ if (!strcmp(str, "none")) {
+ static_call_update(cond_resched, __cond_resched);
+ static_call_update(might_resched, __static_call_return0);
+ static_call_update(preempt_schedule,
(typeof(&preempt_schedule)) NULL);
+ static_call_update(preempt_schedule_notrace,
(typeof(&preempt_schedule_notrace)) NULL);
+ static_call_update(irqentry_exit_cond_resched,
(typeof(&irqentry_exit_cond_resched)) NULL);
+ pr_info("Dynamic Preempt: %s\n", str);
+ } else if (!strcmp(str, "voluntary")) {
+ static_call_update(cond_resched, __cond_resched);
+ static_call_update(might_resched, __cond_resched);
+ static_call_update(preempt_schedule,
(typeof(&preempt_schedule)) NULL);
+ static_call_update(preempt_schedule_notrace,
(typeof(&preempt_schedule_notrace)) NULL);
+ static_call_update(irqentry_exit_cond_resched,
(typeof(&irqentry_exit_cond_resched)) NULL);
+ pr_info("Dynamic Preempt: %s\n", str);
+ } else if (!strcmp(str, "full")) {
+ static_call_update(cond_resched, __static_call_return0);
+ static_call_update(might_resched, __static_call_return0);
+ static_call_update(preempt_schedule, __preempt_schedule_func());
+ static_call_update(preempt_schedule_notrace,
__preempt_schedule_notrace_func());
+ static_call_update(irqentry_exit_cond_resched,
irqentry_exit_cond_resched);
+ pr_info("Dynamic Preempt: %s\n", str);
+ } else {
+ pr_warn("Dynamic Preempt: Unsupported preempt mode %s, default
to full\n", str);
+ return 1;
+ }
+ return 0;
+}
+__setup("preempt=", setup_preempt_mode);
+
+#endif /* CONFIG_PREEMPT_DYNAMIC */
+
+
/*
* This is the entry point to schedule() from kernel preemption
* off of irq context.
--
2.25.1
