From: Alexis Hallé <alexis.halle@polymtl.ca>
Date: Fri, 28 May 2010 17:10:37 +0000 (-0400)
Subject: add environment variables to set subbuffer options
X-Git-Tag: v0.5~6
X-Git-Url: http://git.lttng.org/?p=ust.git;a=commitdiff_plain;h=223f2e7ce070406f507856fa8f0de508d8a05ad3

add environment variables to set subbuffer options

UST_SUBBUF_SIZE and UST_SUBBUF_NUM control respectively the size and
number of subbuffers. Options -S and -N in the usttrace script also
control these parameters.
---

diff --git a/libust/tracectl.c b/libust/tracectl.c
index 7a5cf95..ef0155d 100644
--- a/libust/tracectl.c
+++ b/libust/tracectl.c
@@ -49,6 +49,8 @@
  */
 s64 pidunique = -1LL;
 
+extern struct chan_info_struct chan_infos[];
+
 struct list_head blocked_consumers = LIST_HEAD_INIT(blocked_consumers);
 
 static struct ustcomm_app ustcomm_app;
@@ -1114,6 +1116,11 @@ static void __attribute__((constructor)) init()
 {
 	int result;
 	char* autoprobe_val = NULL;
+	char* subbuffer_size_val = NULL;
+	char* subbuffer_count_val = NULL;
+	unsigned int subbuffer_size;
+	unsigned int subbuffer_count;
+	unsigned int power;
 
 	/* Assign the pidunique, to be able to differentiate the processes with same
 	 * pid, (before and after an exec).
@@ -1197,6 +1204,23 @@ static void __attribute__((constructor)) init()
 		}
 	}
 
+	subbuffer_size_val = getenv("UST_SUBBUF_SIZE");
+	if(subbuffer_size_val) {
+		sscanf(subbuffer_size_val, "%u", &subbuffer_size);
+		power = pow2_higher_or_eq(subbuffer_size);
+		if(power != subbuffer_size)
+			WARN("using the next power of two for buffer size = %u\n", power);
+		chan_infos[LTT_CHANNEL_UST].def_subbufsize = power;
+	}
+
+	subbuffer_count_val = getenv("UST_SUBBUF_NUM");
+	if(subbuffer_count_val) {
+		sscanf(subbuffer_count_val, "%u", &subbuffer_count);
+		if(subbuffer_count < 2)
+			subbuffer_count = 2;
+		chan_infos[LTT_CHANNEL_UST].def_subbufcount = subbuffer_count;
+	}
+
 	if(getenv("UST_TRACE")) {
 		char trace_name[] = "auto";
 		char trace_type[] = "ustrelay";
@@ -1263,7 +1287,6 @@ static void __attribute__((constructor)) init()
 		inform_consumer_daemon(trace_name);
 	}
 
-
 	return;
 
 	/* should decrementally destroy stuff if error */
diff --git a/libust/tracer.c b/libust/tracer.c
index baab461..8c3f774 100644
--- a/libust/tracer.c
+++ b/libust/tracer.c
@@ -69,11 +69,7 @@ int (*ltt_statedump_functor)(struct ust_trace *trace) =
 					ltt_statedump_default;
 struct module *ltt_statedump_owner;
 
-struct chan_info_struct {
-	const char *name;
-	unsigned int def_subbufsize;
-	unsigned int def_subbufcount;
-} chan_infos[] = {
+struct chan_info_struct chan_infos[] = {
 	[LTT_CHANNEL_METADATA] = {
 		LTT_METADATA_CHANNEL,
 		LTT_DEFAULT_SUBBUF_SIZE_LOW,
diff --git a/libust/tracer.h b/libust/tracer.h
index 0fa2e4d..e613482 100644
--- a/libust/tracer.h
+++ b/libust/tracer.h
@@ -86,6 +86,12 @@ enum ltt_channels {
 	LTT_CHANNEL_UST,
 };
 
+struct chan_info_struct {
+	const char *name;
+	unsigned int def_subbufsize;
+	unsigned int def_subbufcount;
+};
+
 struct ltt_active_marker {
 	struct list_head node;		/* active markers list */
 	const char *channel;
diff --git a/usttrace b/usttrace
index 6ffc988..dc159f2 100755
--- a/usttrace
+++ b/usttrace
@@ -54,9 +54,11 @@ function usage () {
 	echo "    -m    Instrument malloc calls." 2>/dev/stderr
 	echo "    -f    Also trace forked processes." 2>/dev/stderr
 	echo "    -s    Use system-wide daemon instead of creating one for this session." 2>/dev/stderr
+	echo "    -S    Specify the subbuffer size." 2>/dev/stderr
+	echo "    -N    Specify the number of subbuffers." 2>/dev/stderr
 }
 
-while getopts ":hlLmfsW" options; do
+while getopts ":hlLmfsWS:N:" options; do
 	case $options in
 		l) arg_preload_libust=1;;
 		L) arg_ld_std_ust=1;;
@@ -64,6 +66,8 @@ while getopts ":hlLmfsW" options; do
 		f) arg_preload_fork=1;;
 		s) arg_syswide_daemon=1;;
 		W) where=1;;
+		S) export UST_SUBBUF_SIZE=$OPTARG;;
+		N) export UST_SUBBUF_NUM=$OPTARG;;
 		h) usage;
 		   exit 0;;
 		\?) usage