X-Git-Url: http://git.efficios.com/?a=blobdiff_plain;f=doc%2Fman%2Flttng.1;h=a8e02fafa11718c70436559071d6069c9d3f4f82;hb=ee8ccafaa999089aa9f6cdc3bc5543cd829c422b;hp=33cc5630432826311cfdd906aeb871307b247493;hpb=23d14dff22683582847cde7ed416a5aeb90e3bd9;p=lttng-tools.git

diff --git a/doc/man/lttng.1 b/doc/man/lttng.1
index 33cc56304..a8e02fafa 100644
--- 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.
@@ -327,14 +328,14 @@ same type.
         Flight recorder mode : overwrites events when subbuffers are full
 \-\-subbuf-size SIZE
         Subbuffer size in bytes (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 (default: 200)
 \-\-output TYPE
         Channel output type. Possible values: mmap, splice
 \-\-buffers-uid
@@ -407,12 +408,12 @@ 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 +424,19 @@ 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]"