From: Julien Desfossez <jdesfossez@efficios.com>
Date: Thu, 6 Dec 2012 15:49:10 +0000 (-0500)
Subject: Limit the number of events enabled in live
X-Git-Tag: v0.3~75
X-Git-Url: http://git.lttng.org/?p=lttngtop.git;a=commitdiff_plain;h=7f856e200eb22faf41d908d6af3fcb5b17fcb98b

Limit the number of events enabled in live

Instead of enabling all the kernel events, we now only activate the
events we need.
On an Intel Core 2 Duo, the CPU usage of LTTngTop in live mode pass
from 3% to 1%.

Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>
---

diff --git a/src/lttngtop.c b/src/lttngtop.c
index dd48a88..ce7607a 100644
--- a/src/lttngtop.c
+++ b/src/lttngtop.c
@@ -1217,10 +1217,32 @@ int setup_live_tracing()
 	}
 
 	memset(&ev, '\0', sizeof(struct lttng_event));
-	//sprintf(ev.name, "sched_switch");
 	ev.type = LTTNG_EVENT_TRACEPOINT;
+	sprintf(ev.name, "sched_switch");
 	if ((ret = lttng_enable_event(handle, &ev, channel_name)) < 0) {
-		fprintf(stderr,"error enabling event : %s\n",
+		fprintf(stderr,"error enabling event %s : %s\n",
+				ev.name,
+				helper_lttcomm_get_readable_code(ret));
+		goto error_session;
+	}
+	sprintf(ev.name, "sched_process_free");
+	if ((ret = lttng_enable_event(handle, &ev, channel_name)) < 0) {
+		fprintf(stderr,"error enabling event %s : %s\n",
+				ev.name,
+				helper_lttcomm_get_readable_code(ret));
+		goto error_session;
+	}
+	sprintf(ev.name, "lttng_statedump_process_state");
+	if ((ret = lttng_enable_event(handle, &ev, channel_name)) < 0) {
+		fprintf(stderr,"error enabling event %s : %s\n",
+				ev.name,
+				helper_lttcomm_get_readable_code(ret));
+		goto error_session;
+	}
+	sprintf(ev.name, "lttng_statedump_file_descriptor");
+	if ((ret = lttng_enable_event(handle, &ev, channel_name)) < 0) {
+		fprintf(stderr,"error enabling event %s : %s\n",
+				ev.name,
 				helper_lttcomm_get_readable_code(ret));
 		goto error_session;
 	}