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tracing: update sample event documentation

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The comments in the sample code is a bit confusing. This patch
cleans them up a little.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt 2009-06-16 19:53:07 -04:00 committed by Steven Rostedt
parent 00e95830a4
commit 44ad18e0a6
2 changed files with 24 additions and 11 deletions
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8
samples/trace_events/Makefile
View File

@ -1,6 +1,14 @@
# builds the trace events example kernel modules; # builds the trace events example kernel modules;
# then to use one (as root): insmod <module_name.ko> # then to use one (as root): insmod <module_name.ko>
# If you include a trace header outside of include/trace/events
# then the file that does the #define CREATE_TRACE_POINTS must
# have that tracer file in its main search path. This is because
# define_trace.h will include it, and must be able to find it from
# the include/trace directory.
#
# Here trace-events-sample.c does the CREATE_TRACE_POINTS.
#
CFLAGS_trace-events-sample.o := -I$(src) CFLAGS_trace-events-sample.o := -I$(src)
obj-$(CONFIG_SAMPLE_TRACE_EVENTS) += trace-events-sample.o obj-$(CONFIG_SAMPLE_TRACE_EVENTS) += trace-events-sample.o

27
samples/trace_events/trace-events-sample.h
View File

@ -19,16 +19,21 @@
* If TRACE_SYSTEM is defined, that will be the directory created * If TRACE_SYSTEM is defined, that will be the directory created
* in the ftrace directory under /debugfs/tracing/events/<system> * in the ftrace directory under /debugfs/tracing/events/<system>
* *
* The define_trace.h belowe will also look for a file name of * The define_trace.h below will also look for a file name of
* TRACE_SYSTEM.h where TRACE_SYSTEM is what is defined here. * TRACE_SYSTEM.h where TRACE_SYSTEM is what is defined here.
* In this case, it would look for sample.h
* *
* If you want a different system than file name, you can override * If the header name will be different than the system name
* the header name by defining TRACE_INCLUDE_FILE * (as in this case), then you can override the header name that
* define_trace.h will look up by defining TRACE_INCLUDE_FILE
* *
* If this file was called, goofy.h, then we would define: * This file is called trace-events-sample.h but we want the system
* to be called "sample". Therefore we must define the name of this
* file:
* *
* #define TRACE_INCLUDE_FILE goofy * #define TRACE_INCLUDE_FILE trace-events-sample
* *
* As we do an the bottom of this file.
*/ */
#undef TRACE_SYSTEM #undef TRACE_SYSTEM
#define TRACE_SYSTEM sample #define TRACE_SYSTEM sample
@ -99,13 +104,13 @@ TRACE_EVENT(foo_bar,
* *
* #define TRACE_INCLUDE_PATH ../../samples/trace_events * #define TRACE_INCLUDE_PATH ../../samples/trace_events
* *
* But I chose to simply make it use the current directory and then in * But the safest and easiest way to simply make it use the directory
* the Makefile I added: * that the file is in is to add in the Makefile:
* *
* CFLAGS_trace-events-sample.o := -I$(PWD)/samples/trace_events/ * CFLAGS_trace-events-sample.o := -I$(src)
* *
* This will make sure the current path is part of the include * This will make sure the current path is part of the include
* structure for our file so that we can find it. * structure for our file so that define_trace.h can find it.
* *
* I could have made only the top level directory the include: * I could have made only the top level directory the include:
* *
@ -115,8 +120,8 @@ TRACE_EVENT(foo_bar,
* *
* #define TRACE_INCLUDE_PATH samples/trace_events * #define TRACE_INCLUDE_PATH samples/trace_events
* *
* But then if something defines "samples" or "trace_events" then we * But then if something defines "samples" or "trace_events" as a macro
* could risk that being converted too, and give us an unexpected * then we could risk that being converted too, and give us an unexpected
* result. * result.
*/ */
#undef TRACE_INCLUDE_PATH #undef TRACE_INCLUDE_PATH