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From: Masami Hiramatsu <mhiramat@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, Tom Zanussi <zanussi@kernel.org>,
	Masami Hiramatsu <mhiramat@kernel.org>
Subject: [PATCH v2 3/9] tracing/boot: Support multiple handlers for per-event histogram
Date: Fri,  6 Aug 2021 01:25:44 +0900	[thread overview]
Message-ID: <162818074413.226227.10373011865940784799.stgit@devnote2> (raw)
In-Reply-To: <162818072104.226227.18088999222035270055.stgit@devnote2>

Support multiple handlers for per-event histogram in boot-time tracing.
Since the histogram can register multiple same handler-actions with
different parameters, this expands the syntax to support such cases.

With this update, the 'onmax', 'onchange' and 'onmatch' handler subkeys
under per-event histogram option will take a number subkeys optionally
as below. (see [.N])

ftrace.[instance.INSTANCE.]event.GROUP.EVENT.hist {
     onmax|onchange[.N] { var = <VAR>; <ACTION> [= <PARAM>] }
     onmatch[.N] { event = <EVENT>; <ACTION> [= <PARAM>] }
}

The 'N' must be a digit (or digit started word).

Thus user can add several handler-actions to the histogram,
for example,

ftrace.event.SOMEGROUP.SOMEEVENT.hist {
   keys = SOME_ID; lat = common_timestamp.usecs-$ts0
   onmatch.1 {
	event = GROUP1.STARTEVENT1
	trace = latency_event, SOME_ID, $lat
   }
   onmatch.2 {
	event = GROUP2.STARTEVENT2
	trace = latency_event, SOME_ID, $lat
   }
}

Then, it can trace the elapsed time from GROUP1.STARTEVENT1 to
SOMEGROUP.SOMEEVENT, and from GROUP2.STARTEVENT2 to
SOMEGROUP.SOMEEVENT with SOME_ID key.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 0 files changed

diff --git a/kernel/trace/trace_boot.c b/kernel/trace/trace_boot.c
index aaaf8b8ed3c9..0db0775d37af 100644
--- a/kernel/trace/trace_boot.c
+++ b/kernel/trace/trace_boot.c
@@ -224,8 +224,9 @@ trace_boot_hist_add_array(struct xbc_node *hnode, char **bufp,
 }
 
 static int __init
-trace_boot_hist_add_handler(struct xbc_node *hnode, char **bufp,
-			    char *end, const char *param)
+trace_boot_hist_add_one_handler(struct xbc_node *hnode, char **bufp,
+				char *end, const char *handler,
+				const char *param)
 {
 	struct xbc_node *knode, *anode;
 	const char *p;
@@ -238,7 +239,7 @@ trace_boot_hist_add_handler(struct xbc_node *hnode, char **bufp,
 		       xbc_node_get_data(hnode), param);
 		return -EINVAL;
 	}
-	append_printf(bufp, end, ":%s(%s)", xbc_node_get_data(hnode), p);
+	append_printf(bufp, end, ":%s(%s)", handler, p);
 
 	/* Compose 'action' parameter */
 	knode = xbc_node_find_child(hnode, "trace");
@@ -273,6 +274,32 @@ trace_boot_hist_add_handler(struct xbc_node *hnode, char **bufp,
 	return 0;
 }
 
+static int __init
+trace_boot_hist_add_handlers(struct xbc_node *hnode, char **bufp,
+			     char *end, const char *param)
+{
+	struct xbc_node *node;
+	const char *p, *handler;
+	int ret;
+
+	handler = xbc_node_get_data(hnode);
+
+	xbc_node_for_each_subkey(hnode, node) {
+		p = xbc_node_get_data(node);
+		if (!isdigit(p[0]))
+			continue;
+		/* All digit started node should be instances. */
+		ret = trace_boot_hist_add_one_handler(node, bufp, end, handler, param);
+		if (ret < 0)
+			break;
+	}
+
+	if (xbc_node_find_child(hnode, param))
+		ret = trace_boot_hist_add_one_handler(hnode, bufp, end, handler, param);
+
+	return ret;
+}
+
 /*
  * Histogram boottime tracing syntax.
  *
@@ -284,8 +311,8 @@ trace_boot_hist_add_handler(struct xbc_node *hnode, char **bufp,
  *	name = <HISTNAME>
  *	var { <VAR> = <EXPR> ... }
  *	pause|continue|clear
- *	onmax|onchange { var = <VAR>; <ACTION> [= <PARAM>] }
- *	onmatch { event = <EVENT>; <ACTION> [= <PARAM>] }
+ *	onmax|onchange[.N] { var = <VAR>; <ACTION> [= <PARAM>] }
+ *	onmatch[.N] { event = <EVENT>; <ACTION> [= <PARAM>] }
  *	filter = <FILTER>
  * }
  *
@@ -345,13 +372,13 @@ trace_boot_compose_hist_cmd(struct xbc_node *hnode, char *buf, size_t size)
 
 	/* Histogram handler and actions */
 	node = xbc_node_find_child(hnode, "onmax");
-	if (node && trace_boot_hist_add_handler(node, &buf, end, "var") < 0)
+	if (node && trace_boot_hist_add_handlers(node, &buf, end, "var") < 0)
 		return -EINVAL;
 	node = xbc_node_find_child(hnode, "onchange");
-	if (node && trace_boot_hist_add_handler(node, &buf, end, "var") < 0)
+	if (node && trace_boot_hist_add_handlers(node, &buf, end, "var") < 0)
 		return -EINVAL;
 	node = xbc_node_find_child(hnode, "onmatch");
-	if (node && trace_boot_hist_add_handler(node, &buf, end, "event") < 0)
+	if (node && trace_boot_hist_add_handlers(node, &buf, end, "event") < 0)
 		return -EINVAL;
 
 	p = xbc_node_find_value(hnode, "filter", NULL);


  parent reply	other threads:[~2021-08-05 16:25 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-05 16:25 [PATCH v2 0/9] tracing/boot: Add histogram syntax support in boot-time tracing Masami Hiramatsu
2021-08-05 16:25 ` [PATCH v2 1/9] tracing/boot: Fix a hist trigger dependency for boot time tracing Masami Hiramatsu
2021-08-07  1:47   ` Steven Rostedt
2021-08-08 14:43     ` Masami Hiramatsu
2021-08-05 16:25 ` [PATCH v2 2/9] tracing/boot: Add per-event histogram action options Masami Hiramatsu
2021-08-05 16:25 ` Masami Hiramatsu [this message]
2021-08-05 16:25 ` [PATCH v2 4/9] tracing/boot: Support multiple histograms for each event Masami Hiramatsu
2021-08-05 16:25 ` [PATCH v2 5/9] tracing/boot: Show correct histogram error command Masami Hiramatsu
2021-08-06  2:58   ` kernel test robot
2021-08-06 14:00     ` Masami Hiramatsu
2021-08-06 18:32       ` Steven Rostedt
2021-08-05 16:26 ` [PATCH v2 6/9] Documentation: tracing: Add histogram syntax to boot-time tracing Masami Hiramatsu
2021-08-05 16:26 ` [PATCH v2 7/9] tools/bootconfig: Support per-group/all event enabling option Masami Hiramatsu
2021-08-05 16:26 ` [PATCH v2 8/9] tools/bootconfig: Add histogram syntax support to bconf2ftrace.sh Masami Hiramatsu
2021-08-05 16:26 ` [PATCH v2 9/9] tools/bootconfig: Use per-group/all enable option in ftrace2bconf script Masami Hiramatsu

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