aboutsummaryrefslogtreecommitdiffstats
path: root/include/linux
diff options
context:
space:
mode:
authorIngo Molnar <mingo@elte.hu>2009-03-10 17:55:31 -0400
committerIngo Molnar <mingo@elte.hu>2009-03-10 17:55:31 -0400
commite2b8b2808538a91444e78c7db5a30519cadd09b2 (patch)
tree60c45581817db746bd61670f5c95b19c2661daa0 /include/linux
parent4dd163a0512eb91bbcf4e66d2f65b8e4042561b3 (diff)
parentef18012b248b47ec9a12c3a83ca5e99782d39c5d (diff)
Merge branch 'tip/tracing/ftrace' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into tracing/ftrace
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/tracepoint.h105
1 files changed, 104 insertions, 1 deletions
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 69b56988813d..d35a7ee7611f 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -157,7 +157,110 @@ static inline void tracepoint_synchronize_unregister(void)
157#define TRACE_FORMAT(name, proto, args, fmt) \ 157#define TRACE_FORMAT(name, proto, args, fmt) \
158 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 158 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
159 159
160#define TRACE_EVENT(name, proto, args, struct, print, assign) \ 160
161/*
162 * For use with the TRACE_EVENT macro:
163 *
164 * We define a tracepoint, its arguments, its printk format
165 * and its 'fast binay record' layout.
166 *
167 * Firstly, name your tracepoint via TRACE_EVENT(name : the
168 * 'subsystem_event' notation is fine.
169 *
170 * Think about this whole construct as the
171 * 'trace_sched_switch() function' from now on.
172 *
173 *
174 * TRACE_EVENT(sched_switch,
175 *
176 * *
177 * * A function has a regular function arguments
178 * * prototype, declare it via TP_PROTO():
179 * *
180 *
181 * TP_PROTO(struct rq *rq, struct task_struct *prev,
182 * struct task_struct *next),
183 *
184 * *
185 * * Define the call signature of the 'function'.
186 * * (Design sidenote: we use this instead of a
187 * * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
188 * *
189 *
190 * TP_ARGS(rq, prev, next),
191 *
192 * *
193 * * Fast binary tracing: define the trace record via
194 * * TP_STRUCT__entry(). You can think about it like a
195 * * regular C structure local variable definition.
196 * *
197 * * This is how the trace record is structured and will
198 * * be saved into the ring buffer. These are the fields
199 * * that will be exposed to user-space in
200 * * /debug/tracing/events/<*>/format.
201 * *
202 * * The declared 'local variable' is called '__entry'
203 * *
204 * * __field(pid_t, prev_prid) is equivalent to a standard declariton:
205 * *
206 * * pid_t prev_pid;
207 * *
208 * * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
209 * *
210 * * char prev_comm[TASK_COMM_LEN];
211 * *
212 *
213 * TP_STRUCT__entry(
214 * __array( char, prev_comm, TASK_COMM_LEN )
215 * __field( pid_t, prev_pid )
216 * __field( int, prev_prio )
217 * __array( char, next_comm, TASK_COMM_LEN )
218 * __field( pid_t, next_pid )
219 * __field( int, next_prio )
220 * ),
221 *
222 * *
223 * * Assign the entry into the trace record, by embedding
224 * * a full C statement block into TP_fast_assign(). You
225 * * can refer to the trace record as '__entry' -
226 * * otherwise you can put arbitrary C code in here.
227 * *
228 * * Note: this C code will execute every time a trace event
229 * * happens, on an active tracepoint.
230 * *
231 *
232 * TP_fast_assign(
233 * memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
234 * __entry->prev_pid = prev->pid;
235 * __entry->prev_prio = prev->prio;
236 * memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
237 * __entry->next_pid = next->pid;
238 * __entry->next_prio = next->prio;
239 * )
240 *
241 * *
242 * * Formatted output of a trace record via TP_printk().
243 * * This is how the tracepoint will appear under ftrace
244 * * plugins that make use of this tracepoint.
245 * *
246 * * (raw-binary tracing wont actually perform this step.)
247 * *
248 *
249 * TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
250 * __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
251 * __entry->next_comm, __entry->next_pid, __entry->next_prio),
252 *
253 * );
254 *
255 * This macro construct is thus used for the regular printk format
256 * tracing setup, it is used to construct a function pointer based
257 * tracepoint callback (this is used by programmatic plugins and
258 * can also by used by generic instrumentation like SystemTap), and
259 * it is also used to expose a structured trace record in
260 * /debug/tracing/events/.
261 */
262
263#define TRACE_EVENT(name, proto, args, struct, assign, print) \
161 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args)) 264 DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
162 265
163#endif 266#endif