xiaoxiang781216 commented on code in PR #16673:
URL: https://github.com/apache/nuttx/pull/16673#discussion_r2229245524
##########
sched/sched/sched_unlock.c:
##########
@@ -81,18 +89,28 @@ void sched_unlock(void)
sched_note_preemption(rtcb, false);
/* Release any ready-to-run tasks that have collected in
- * g_pendingtasks.
+ * g_pendingtasks (or in g_readytorun for SMP)
*
* NOTE: This operation has a very high likelihood of causing
* this task to be switched out!
*/
- if (list_pendingtasks()->head != NULL)
+#ifdef CONFIG_SMP
+ /* If this task is the lowest priority task running across all
+ * CPUs, there may be some higher priority task pending because
+ * of the sched lock.
+ */
+
+ ptcb = (FAR struct tcb_s *)dq_peek(list_readytorun());
+ if (ptcb && nxsched_select_cpu(ALL_CPUS) == rtcb->cpu &&
+ ptcb->sched_priority > rtcb->sched_priority &&
+ nxsched_deliver_task(rtcb->cpu, rtcb->cpu))
Review Comment:
why not call nxsched_switch_running directly
##########
sched/sched/sched_unlock.c:
##########
@@ -81,18 +89,28 @@ void sched_unlock(void)
sched_note_preemption(rtcb, false);
/* Release any ready-to-run tasks that have collected in
- * g_pendingtasks.
+ * g_pendingtasks (or in g_readytorun for SMP)
*
* NOTE: This operation has a very high likelihood of causing
* this task to be switched out!
*/
- if (list_pendingtasks()->head != NULL)
+#ifdef CONFIG_SMP
+ /* If this task is the lowest priority task running across all
+ * CPUs, there may be some higher priority task pending because
+ * of the sched lock.
+ */
+
+ ptcb = (FAR struct tcb_s *)dq_peek(list_readytorun());
+ if (ptcb && nxsched_select_cpu(ALL_CPUS) == rtcb->cpu &&
+ ptcb->sched_priority > rtcb->sched_priority &&
+ nxsched_deliver_task(rtcb->cpu, rtcb->cpu))
+#else
+ ptcb = (FAR struct tcb_s *)dq_peek(list_pendingtasks());
+ if (ptcb && nxsched_merge_pending())
Review Comment:
why need check ptcb before nxsched_merge_pending
##########
sched/sched/sched.h:
##########
@@ -518,23 +521,51 @@ static inline_function bool nxsched_add_prioritized(FAR
struct tcb_s *tcb,
}
# ifdef CONFIG_SMP
+
+/* Try to switch the head of the ready-to-run list to active on "cpu".
+ * "curr_cpu" is "this_cpu()", and passed only for optimization.
+ */
+
+static inline_function bool nxsched_deliver_task(int cpu, int curr_cpu)
Review Comment:
let's change argument to (int cpu, int target_cpu)
##########
sched/sched/sched_suspend.c:
##########
@@ -172,9 +176,13 @@ void nxsched_suspend(FAR struct tcb_s *tcb)
{
switch_needed = nxsched_remove_readytorun(tcb);
- if (list_pendingtasks()->head)
+ if (!nxsched_islocked_tcb(rtcb) || switch_needed)
Review Comment:
why not check switch_needed first
##########
sched/sched/sched.h:
##########
@@ -518,23 +514,51 @@ static inline_function bool nxsched_add_prioritized(FAR
struct tcb_s *tcb,
}
# ifdef CONFIG_SMP
+
+/* Try to switch the head of the ready-to-run list to active on "cpu".
+ * "curr_cpu" is "this_cpu()", and passed only for optimization.
+ */
+
+static inline_function bool nxsched_deliver_task(int cpu, int curr_cpu)
+{
+ bool ret = false;
+
+ /* If there is already a schedule interrupt pending, there is
+ * no need to do anything now.
+ */
+
+ if (!g_delivertasks[cpu])
Review Comment:
should we change to:
```
if (cpu == curr_cpu)
{
ret = nxsched_switch_running(cpu);
}
else if (!g_delivertasks[cpu])
{
g_delivertasks[cpu] = true;
up_send_smp_sched(cpu);
}
```
##########
sched/sched/sched_unlock.c:
##########
@@ -81,18 +89,28 @@ void sched_unlock(void)
sched_note_preemption(rtcb, false);
/* Release any ready-to-run tasks that have collected in
- * g_pendingtasks.
+ * g_pendingtasks (or in g_readytorun for SMP)
*
* NOTE: This operation has a very high likelihood of causing
* this task to be switched out!
*/
- if (list_pendingtasks()->head != NULL)
+#ifdef CONFIG_SMP
+ /* If this task is the lowest priority task running across all
+ * CPUs, there may be some higher priority task pending because
+ * of the sched lock.
+ */
+
+ ptcb = (FAR struct tcb_s *)dq_peek(list_readytorun());
+ if (ptcb && nxsched_select_cpu(ALL_CPUS) == rtcb->cpu &&
Review Comment:
should we pass the affinity mask of ptcb instead ALL_CPUS?
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