lttng cli: Accept human readable sizes for --subbuf-size

[lttng-tools.git] / doc / man / lttng.1

diff --git a/doc/man/lttng.1 b/doc/man/lttng.1
index 33cc5630432826311cfdd906aeb871307b247493..65fa3d17f465e2a2fcd1dbfb4ef0da8fd1d1c477 100644 (file)
--- a/doc/man/lttng.1
+++ b/doc/man/lttng.1
@@ -297,7 +297,8 @@ If NAME is omitted, the session name is taken from the .lttngrc file.
 .nf
 Enable tracing channel
 
-To enable event, you must first enable a channel which contains event(s).
+To enable an event, you must enable both the event and the channel that
+contains it.
 
 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
 file.
@@ -326,15 +327,15 @@ same type.
 \-\-overwrite
         Flight recorder mode : overwrites events when subbuffers are full
 \-\-subbuf-size SIZE
-        Subbuffer size in bytes (default: 4096, kernel default: 262144)
+        Subbuffer size in bytes {+k,+M,+G} (default: 4096, kernel default: 262144)
+        Needs to be a power of 2 for both tracers
 \-\-num-subbuf NUM
         Number of subbuffers (default: 4)
-        Needs to be a power of 2 for kernel and ust tracers
+        Needs to be a power of 2 for both tracers
 \-\-switch-timer USEC
-        Switch subbuffer timer interval in usec (default: 0)
-        Needs to be a power of 2 for kernel and ust tracers
+        Switch subbuffer timer interval in µsec (default: 0)
 \-\-read-timer USEC
-        Read timer interval in usec (default: 200)
+        Read timer interval in µsec (UST default: 0, kernel default: 200000)
 \-\-output TYPE
         Channel output type. Possible values: mmap, splice
 \-\-buffers-uid
@@ -344,6 +345,29 @@ same type.
         Use per PID buffer (\-u only). Each application has its own buffers.
 \-\-buffers-global
         Use shared buffer for the whole system (\-k only)
+\-C, \-\-tracefile-size SIZE
+        Maximum size of each tracefile within a stream (in bytes).
+\-W, \-\-tracefile-count COUNT
+        Used in conjunction with \-C option, this will limit the number
+        of files created to the specified count.
+
+.B EXAMPLES:
+
+$ lttng enable-channel -C 4096 -W 32 chan1
+For each stream, the maximum size of a trace file will be 4096 bytes divided
+over a \fBmaximum\fP of 32 different files. The file count is appended after
+the stream number as seen in the following example. The last trace file is
+smaller than 4096 since it was not completely filled.
+
+        ~/lttng-traces/[...]/chan1_0_0 (4096)
+        ~/lttng-traces/[...]/chan1_0_1 (4096)
+        ~/lttng-traces/[...]/chan1_0_2 (3245)
+        ~/lttng-traces/[...]/chan1_1_0 (4096)
+        ...
+
+$ lttng enable-channel -C 4096
+This will create trace files of 4096 bytes and will create new ones as long as
+there is data available.
 .fi
 
 .IP
@@ -407,12 +431,12 @@ file.
 
 \-\-filter 'expression'
         Set a filter on a newly enabled event. Filter expression on event
-        fields, event recording depends on evaluation. Only specify on first
-        activation of a given event within a session. Filter only allowed when
-        enabling events within a session before tracing is started. If the
-        filter fails to link with the event within the traced domain, the event
-        will be discarded. Currently, filter is only implemented for the
-        user-space tracer.
+       fields and context. Event recording depends on evaluation. Only
+       specify on first activation of a given event within a session.
+       Filter only allowed when enabling events within a session before
+       tracing is started. If the filter fails to link with the event
+       within the traced domain, the event will be discarded.
+       Currently, filter is only implemented for the user-space tracer.
 
         Expression examples:
 
@@ -423,7 +447,19 @@ file.
         Wildcards are allowed at the end of strings:
         'seqfield1 == "te*"'
         In string literals, the escape character is a '\\'. Use '\\*' for
-        the '*' character, and '\\\\' for the '\\' character.
+        the '*' character, and '\\\\' for the '\\' character. Wildcard
+       match any sequence of characters, including an empty sub-string
+       (match 0 or more characters).
+
+       Context information can be used for filtering. The examples
+       below show usage of context filtering on process name (with a
+       wildcard), process ID range, and unique thread ID for filtering.
+       The process and thread ID of running applications can be found
+       under columns "PID" and "LWP" of the "ps -eLf" command.
+
+       '$ctx.procname == "demo*"'
+       '$ctx.vpid >= 4433 && $ctx.vpid < 4455'
+       '$ctx.vtid == 1234'
 .fi
 
 .IP "\fBdisable-channel\fP NAME[,NAME2,...] [\-k|\-u] [OPTIONS]"