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>

1 files changed, 4 insertions, 2 deletions

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index b31d3d5699fe..1a2117043bb1 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1002,7 +1002,8 @@ static __kprobes void kprobe_perf_func(struct kprobe *kp,
         store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
 
         head = this_cpu_ptr(call->perf_events);
-        perf_trace_buf_submit(entry, size, rctx, entry->ip, 1, regs, head);
+        perf_trace_buf_submit(entry, size, rctx,
+                                        entry->ip, 1, regs, head, NULL);
 }
 
 /* Kretprobe profile handler */
@@ -1033,7 +1034,8 @@ static __kprobes void kretprobe_perf_func(struct kretprobe_instance *ri,
         store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
 
         head = this_cpu_ptr(call->perf_events);
-        perf_trace_buf_submit(entry, size, rctx, entry->ret_ip, 1, regs, head);
+        perf_trace_buf_submit(entry, size, rctx,
+                                        entry->ret_ip, 1, regs, head, NULL);
 }
 #endif  /* CONFIG_PERF_EVENTS */