Commit 8993665a authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Steven Rostedt (VMware)
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tracing/boot: Support multiple handlers for per-event histogram 

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.

Link: https://lkml.kernel.org/r/162856124905.203126.14913731908137885922.stgit@devnote2



Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent e66ed86c

kernel/trace/trace_boot.c

+35 −8
Original line number Diff line number Diff line
@@ -245,8 +245,9 @@ 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;
@@ -259,7 +260,7 @@ 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");
@@ -294,6 +295,32 @@ 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.

 *
@@ -305,8 +332,8 @@ 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>

 * }

 *
@@ -368,13 +395,13 @@ 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);