While making up its mind about whether to reschedule a target
runqueue eagerly or lazily, resched_curr() needs to know if the
target is executing in the kernel or in userspace.
Add ct_state_cpu().
Signed-off-by: Ankur Arora <ankur.a.arora@xxxxxxxxxx>
---
Using context-tracking for this seems like overkill. Is there a better
way to achieve this? One problem with depending on user_enter() is that
it happens much too late for our purposes. From the scheduler's
point-of-view the exit state has effectively transitioned once the
task exits the exit_to_user_loop() so we will see stale state
while the task is done with exit_to_user_loop() but has not yet
executed user_enter().
---
include/linux/context_tracking_state.h | 21 +++++++++++++++++++++
kernel/Kconfig.preempt | 1 +
2 files changed, 22 insertions(+)
diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h
index bbff5f7f8803..6a8f1c7ba105 100644
--- a/include/linux/context_tracking_state.h
+++ b/include/linux/context_tracking_state.h
@@ -53,6 +53,13 @@ static __always_inline int __ct_state(void)
{
return raw_atomic_read(this_cpu_ptr(&context_tracking.state)) & CT_STATE_MASK;
}
+
+static __always_inline int __ct_state_cpu(int cpu)
+{
+ struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
+
+ return atomic_read(&ct->state) & CT_STATE_MASK;
+}
#endif
#ifdef CONFIG_CONTEXT_TRACKING_IDLE
@@ -139,6 +146,20 @@ static __always_inline int ct_state(void)
return ret;
}
+static __always_inline int ct_state_cpu(int cpu)
+{
+ int ret;
+
+ if (!context_tracking_enabled_cpu(cpu))
+ return CONTEXT_DISABLED;
+
+ preempt_disable();
+ ret = __ct_state_cpu(cpu);
+ preempt_enable();
+
+ return ret;
+}
+
#else
static __always_inline bool context_tracking_enabled(void) { return false; }
static __always_inline bool context_tracking_enabled_cpu(int cpu) { return false; }
diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt
index 715e7aebb9d8..aa87b5cd3ecc 100644
--- a/kernel/Kconfig.preempt
+++ b/kernel/Kconfig.preempt
@@ -80,6 +80,7 @@ config PREEMPT_COUNT
config PREEMPTION
bool
select PREEMPT_COUNT
+ select CONTEXT_TRACKING_USER
config SCHED_CORE
bool "Core Scheduling for SMT"
--
2.31.1
