lttng-enable-channel(1): document --monitor-timer

[lttng-tools.git] / doc / man / lttng-enable-channel.1.txt

diff --git a/doc/man/lttng-enable-channel.1.txt b/doc/man/lttng-enable-channel.1.txt
index bec0906428c5bfba6e9f91ab3e8f783cd96b472e..cad26a8643edf052a67bd0aa0738cfe834c14ba5 100644 (file)
--- a/doc/man/lttng-enable-channel.1.txt
+++ b/doc/man/lttng-enable-channel.1.txt
@@ -16,6 +16,7 @@ Create a Linux kernel channel:
       [option:--overwrite] [option:--output=(`mmap` | `splice`)]
       [option:--subbuf-size='SIZE'] [option:--num-subbuf='COUNT']
       [option:--switch-timer='PERIODUS'] [option:--read-timer='PERIODUS']
+      [option:--monitor-timer='PERIODUS']
       [option:--tracefile-size='SIZE'] [option:--tracefile-count='COUNT']
       [option:--session='SESSION'] 'CHANNEL'
 
@@ -26,7 +27,7 @@ Create a user space channel:
       [option:--overwrite] [option:--buffers-pid]
       [option:--subbuf-size='SIZE'] [option:--num-subbuf='COUNT']
       [option:--switch-timer='PERIODUS'] [option:--read-timer='PERIODUS']
-      [option:--blocking-timeout='TIMEOUTUS']
+      [option:--monitor-timer='PERIODUS'] [option:--blocking-timeout='TIMEOUTUS']
       [option:--tracefile-size='SIZE'] [option:--tracefile-count='COUNT']
       [option:--session='SESSION'] 'CHANNEL'
 
@@ -148,8 +149,8 @@ parameter is pointless: using two sub-buffers and setting their size
 according to the requirements of the context is fine.
 
 
-Switch and read timers
-~~~~~~~~~~~~~~~~~~~~~~
+Switch timer
+~~~~~~~~~~~~
 When a channel's switch timer fires, a sub-buffer switch happens. This
 timer may be used to ensure that event data is consumed and committed
 to trace files periodically in case of a low event throughput.
@@ -157,11 +158,36 @@ to trace files periodically in case of a low event throughput.
 It's also convenient when big sub-buffers are used to cope with sporadic
 high event throughput, even if the throughput is normally lower.
 
-By default, a notification mechanism is used to signal a full sub-buffer
-so that it can be consumed. When such notifications must be avoided,
-for example in real-time applications, the channel's read timer can be
-used instead. When the read timer fires, sub-buffers are checked for
-consumption when they are full.
+Use the option:--switch-timer option to control the switch timer's
+period of the channel to create.
+
+
+Read timer
+~~~~~~~~~~
+By default, an internal notification mechanism is used to signal a full
+sub-buffer so that it can be consumed. When such notifications must be
+avoided, for example in real-time applications, the channel's read timer
+can be used instead. When the read timer fires, sub-buffers are checked
+for consumption when they are full.
+
+Use the option:--read-timer option to control the read timer's period of
+the channel to create.
+
+
+Monitor timer
+~~~~~~~~~~~~~
+When a channel's monitor timer fires, its registered trigger conditions
+are evaluated using the current values of its properties (for example,
+the current usage of its sub-buffers). When a trigger condition is true,
+LTTng executes its associated action. The only type of action currently
+supported is to notify one or more user applications.
+
+See the installed $$C/C++$$ headers in `lttng/action`,
+`lttng/condition`, `lttng/notification`, and `lttng/trigger` to learn
+more about application notifications and triggers.
+
+Use the option:--monitor-timer option to control the monitor timer's
+period of the channel to create.
 
 
 Buffering scheme
@@ -333,6 +359,18 @@ discarded events as of CTF 1.8.
 
 Timers
 ~~~~~~
+option:--monitor-timer::
+    Set the channel's monitor timer's period to 'PERIODUS' µs. 0 means a
+    disabled monitor timer.
++
+Default values:
++
+* option:--userspace and option:--buffers-uid options:
+  {default_ust_uid_channel_monitor_timer}
+* option:--userspace and option:--buffers-pid options:
+  {default_ust_pid_channel_monitor_timer}
+* option:--kernel option: {default_kernel_channel_monitor_timer}
+
 option:--read-timer::
     Set the channel's read timer's period to 'PERIODUS' µs. 0 means a
     disabled read timer.