perf/ftrace: Optimize perf/tracepoint interaction for single events

When we've got but a single event per tracepoint
there is no reason to try and multiplex it so don't.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

3 files changed, 13 insertions, 8 deletions

diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 0565bb4..89b780a 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -27,13 +27,15 @@ typedef typeof(unsigned long [PERF_MAX_TRACE_SIZE / sizeof(unsigned long)])
 /* Count the events in use (per event id, not per instance) */
 static int	total_ref_count;
 
-static int perf_trace_event_enable(struct ftrace_event_call *event)
+static int perf_trace_event_enable(struct ftrace_event_call *event, void *data)
 {
 	char *buf;
 	int ret = -ENOMEM;
 
-	if (event->perf_refcount++ > 0)
+	if (event->perf_refcount++ > 0) {
+		event->perf_data = NULL;
 		return 0;
+	}
 
 	if (!total_ref_count) {
 		buf = (char *)alloc_percpu(perf_trace_t);
@@ -51,6 +53,7 @@ static int perf_trace_event_enable(struct ftrace_event_call *event)
 
 	ret = event->perf_event_enable(event);
 	if (!ret) {
+		event->perf_data = data;
 		total_ref_count++;
 		return 0;
 	}
@@ -68,7 +71,7 @@ fail_buf:
 	return ret;
 }
 
-int perf_trace_enable(int event_id)
+int perf_trace_enable(int event_id, void *data)
 {
 	struct ftrace_event_call *event;
 	int ret = -EINVAL;
@@ -77,7 +80,7 @@ int perf_trace_enable(int event_id)
 	list_for_each_entry(event, &ftrace_events, list) {
 		if (event->id == event_id && event->perf_event_enable &&
 		    try_module_get(event->mod)) {
-			ret = perf_trace_event_enable(event);
+			ret = perf_trace_event_enable(event, data);
 			break;
 		}
 	}
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index a751432..2d7bf41 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1362,7 +1362,7 @@ static __kprobes void kprobe_perf_func(struct kprobe *kp,
 	for (i = 0; i < tp->nr_args; i++)
 		call_fetch(&tp->args[i].fetch, regs, data + tp->args[i].offset);
 
-	perf_trace_buf_submit(entry, size, rctx, entry->ip, 1, irq_flags, regs);
+	perf_trace_buf_submit(entry, size, rctx, entry->ip, 1, irq_flags, regs, call->perf_data);
 }
 
 /* Kretprobe profile handler */
@@ -1395,7 +1395,7 @@ static __kprobes void kretprobe_perf_func(struct kretprobe_instance *ri,
 		call_fetch(&tp->args[i].fetch, regs, data + tp->args[i].offset);
 
 	perf_trace_buf_submit(entry, size, rctx, entry->ret_ip, 1,
-			       irq_flags, regs);
+			       irq_flags, regs, call->perf_data);
 }
 
 static int probe_perf_enable(struct ftrace_event_call *call)
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 4d6d711..9eff1a4 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -468,7 +468,8 @@ static void perf_syscall_enter(struct pt_regs *regs, long id)
 	rec->nr = syscall_nr;
 	syscall_get_arguments(current, regs, 0, sys_data->nb_args,
 			       (unsigned long *)&rec->args);
-	perf_trace_buf_submit(rec, size, rctx, 0, 1, flags, regs);
+	perf_trace_buf_submit(rec, size, rctx, 0, 1, flags, regs,
+			sys_data->enter_event->perf_data);
 }
 
 int perf_sysenter_enable(struct ftrace_event_call *call)
@@ -543,7 +544,8 @@ static void perf_syscall_exit(struct pt_regs *regs, long ret)
 	rec->nr = syscall_nr;
 	rec->ret = syscall_get_return_value(current, regs);
 
-	perf_trace_buf_submit(rec, size, rctx, 0, 1, flags, regs);
+	perf_trace_buf_submit(rec, size, rctx, 0, 1, flags, regs,
+			sys_data->exit_event->perf_data);
 }
 
 int perf_sysexit_enable(struct ftrace_event_call *call)