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new 5e5137adee2 Documentation/applications/system/critmon: add critmon man
page
5e5137adee2 is described below
commit 5e5137adee2e6fc838df9cb52fcdac579bf78266
Author: hanzhijian <[email protected]>
AuthorDate: Sun Jun 14 06:12:03 2026 +0800
Documentation/applications/system/critmon: add critmon man page
Add documentation for the critmon command including:
- critmon (one-shot dump)
- critmon_start (start daemon)
- critmon_stop (stop daemon)
- Output format explanation
- Configuration options
Signed-off-by: hanzhijian <[email protected]>
---
.../applications/system/critmon/index.rst | 91 ++++++++++++++++++++++
1 file changed, 91 insertions(+)
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b/Documentation/applications/system/critmon/index.rst
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+====================================
+``critmon`` critical section monitor
+====================================
+
+The ``critmon`` command displays critical section and pre-emption timing
+information for all tasks and threads in the system. It reads from the
+procfs ``critmon`` and ``status`` files for each process/thread.
+
+Three commands are provided:
+
+- ``critmon``: One-shot dump of critical section timing data.
+- ``critmon_start``: Start the background monitoring daemon.
+- ``critmon_stop``: Stop the background monitoring daemon.
+
+The daemon periodically samples critical section usage at a configurable
+interval (default: 2 seconds) and prints the timing information.
+
+Configuration
+=============
+
+- ``CONFIG_SCHED_CRITMONITOR``: Enable the critical section monitor
+ in the kernel (required dependency).
+- ``CONFIG_FS_PROCFS``: Enable procfs filesystem support.
+- ``CONFIG_SYSTEM_CRITMONITOR``: Enable the critmon system tool.
+
+The following additional options are available:
+
+- ``CONFIG_SYSTEM_CRITMONITOR_DAEMON_STACKSIZE`` - Stack size for the
+ daemon task (default: 2048).
+- ``CONFIG_SYSTEM_CRITMONITOR_DAEMON_PRIORITY`` - Priority for the
+ daemon task (default: 50).
+- ``CONFIG_SYSTEM_CRITMONITOR_INTERVAL`` - Sampling interval in
+ seconds (default: 2).
+- ``CONFIG_SYSTEM_CRITMONITOR_MOUNTPOINT`` - procfs mount point
+ (default: ``/proc``).
+
+Usage
+=====
+
+.. code-block:: text
+
+ critmon
+ critmon_start
+ critmon_stop
+
+Output Format
+=============
+
+The output shows a table with the following columns:
+
+- **PRE-EMPTION CALLER**: The function that most recently enabled
+ pre-emption for this task.
+- **CSECTION CALLER**: The function that most recently entered a
+ critical section.
+- **RUN**: Maximum time spent in a critical section.
+- **TIME**: Total accumulated critical section time.
+- **PID**: Process/thread ID.
+- **DESCRIPTION**: Task name (if ``CONFIG_TASK_NAME_SIZE > 0``).
+
+Examples
+========
+
+One-shot dump of critical section timing:
+
+.. code-block:: text
+
+ nsh> critmon
+ PRE-EMPTION CALLER CSECTION CALLER RUN
TIME PID DESCRIPTION
+ nxtask_exit nxtask_init 0.000010000
0.000010000 0 Idle_Task
+ nxtask_init up_irq_save 0.000005000
0.000015000 1 hpwork 0x10001000
+
+Start the monitoring daemon (prints every 2 seconds):
+
+.. code-block:: text
+
+ nsh> critmon_start
+ Csection Monitor: Started: 5
+
+Stop the monitoring daemon:
+
+.. code-block:: text
+
+ nsh> critmon_stop
+ Csection Monitor: Stopping: 5
+ Csection Monitor: Stopped: 5
+
+See Also
+========
+
+- :doc:`../stackmonitor/index`
+- :doc:`../gprof/index`
