perf/trace: Add ability to set a target task for events

A few events are interesting not only for a current task.
For example, sched_stat_* events are interesting for a task
which wakes up. For this reason, it will be good if such
events will be delivered to a target task too.

Now a target task can be set by using __perf_task().

The original idea and a draft patch belongs to Peter Zijlstra.

I need these events for profiling sleep times. sched_switch is used for
getting callchains and sched_stat_* is used for getting time periods.
These events are combined in user space, then it can be analyzed by
perf tools.

Inspired-by: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Arun Sharma <asharma@fb.com>
Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1342016098-213063-1-git-send-email-avagin@openvz.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 5 insertions, 3 deletions

diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index af961d6f7ab1..642928cf57b4 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -306,9 +306,10 @@ extern void *perf_trace_buf_prepare(int size, unsigned short type,
 
 static inline void
 perf_trace_buf_submit(void *raw_data, int size, int rctx, u64 addr,
-                       u64 count, struct pt_regs *regs, void *head)
+                       u64 count, struct pt_regs *regs, void *head,
+                       struct task_struct *task)
 {
-        perf_tp_event(addr, count, raw_data, size, regs, head, rctx);
+        perf_tp_event(addr, count, raw_data, size, regs, head, rctx, task);
 }
 #endif
 
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 76c5c8b724a7..7602ccb3f40e 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1272,7 +1272,8 @@ static inline bool perf_paranoid_kernel(void)
 extern void perf_event_init(void);
 extern void perf_tp_event(u64 addr, u64 count, void *record,
                           int entry_size, struct pt_regs *regs,
-                          struct hlist_head *head, int rctx);
+                          struct hlist_head *head, int rctx,
+                          struct task_struct *task);
 extern void perf_bp_event(struct perf_event *event, void *data);
 
 #ifndef perf_misc_flags