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new d5b02b6954e sched/critmon: Fix CPU load stats incorrect when using
SCHED_CPULOAD_CRITMONITOR
d5b02b6954e is described below
commit d5b02b6954ec8d58815ede4a69ccad9365a4b4bc
Author: chao an <[email protected]>
AuthorDate: Tue Mar 3 17:04:30 2026 +0800
sched/critmon: Fix CPU load stats incorrect when using
SCHED_CPULOAD_CRITMONITOR
Fix the abnormal CPU usage statistics issue caused by missing update
of run_start timestamp in the target task (to) TCB when the CPU load
counting mode is SCHED_CPULOAD_CRITMONITOR.
Before this fix, the to->run_start was not set when switching context,
leading to incorrect CPU usage calculation (e.g., Idle_Task showed 52.9%
CPU usage instead of 100%, and running tasks had wrong non-zero values).
After fixing, the CPU statistics return to normal: Idle_Task correctly
shows 100% usage, and non-running tasks show 0% as expected.
Enable:
+CONFIG_SCHED_CPULOAD_CRITMONITOR=y
+CONFIG_SCHED_CRITMONITOR=y
Before:
nsh> ps
TID PID PPID PRI POLICY TYPE NPX STATE EVENT SIGMASK
STACK CPU COMMAND
0 0 0 0 FIFO Kthread - Ready
0000000000000000 0069584 52.9% Idle_Task
1 0 0 224 FIFO Kthread - Waiting Semaphore
0000000000000000 0067456 0.0% sim_loop_wq 0x7b4417a003f0 0x7b4417a00470
2 0 0 224 FIFO Kthread - Waiting Semaphore
0000000000000000 0067464 17.6% hpwork 0x4014dba0 0x4014dc20
3 3 0 100 FIFO Task - Running
0000000000000000 0067496 36.8% nsh_main
After:
nsh> ps
TID PID PPID PRI POLICY TYPE NPX STATE EVENT SIGMASK
STACK CPU COMMAND
0 0 0 0 FIFO Kthread - Ready
0000000000000000 0069584 100.0% Idle_Task
1 0 0 224 FIFO Kthread - Waiting Semaphore
0000000000000000 0067456 0.0% sim_loop_wq 0x7646932003f0 0x764693200470
2 0 0 224 FIFO Kthread - Waiting Semaphore
0000000000000000 0067464 0.0% hpwork 0x4014dba0 0x4014dc20
3 3 0 100 FIFO Task - Running
0000000000000000 0067496 0.0% nsh_main
This issue was introduced by PR #17075, where the run_start update for the
target task was omitted in the SCHED_CPULOAD_CRITMONITOR branch.
Signed-off-by: chao an <[email protected]>
---
sched/sched/sched_critmonitor.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/sched/sched/sched_critmonitor.c b/sched/sched/sched_critmonitor.c
index 94c944b79c2..c4c3f213e1f 100644
--- a/sched/sched/sched_critmonitor.c
+++ b/sched/sched/sched_critmonitor.c
@@ -375,6 +375,7 @@ void nxsched_switch_critmon(FAR struct tcb_s *from, FAR
struct tcb_s *to)
#ifdef CONFIG_SCHED_CPULOAD_CRITMONITOR
clock_t tick = elapsed * CLOCKS_PER_SEC / perf_getfreq();
nxsched_critmon_cpuload(from, current, tick);
+ to->run_start = current;
#endif
#if CONFIG_SCHED_CRITMONITOR_MAXTIME_THREAD >= 0
