Commit 17abd7c3 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Steven Rostedt (VMware)
Browse files

tracing/boot: Support multiple histograms for each event 

Add multiple histograms support for each event. This allows
user to set multiple histograms to an event.

ftrace.[instance.INSTANCE.]event.GROUP.EVENT.hist[.N] {
...
}

The 'N' is a digit started string and it can be omitted
for the default histogram.

For example, multiple hist triggers example in the
Documentation/trace/histogram.rst can be written as below;

ftrace.event.net.netif_receive_skb.hist {
	1 {
		keys = skbaddr.hex
		values = len
		filter = len < 0
	}
	2 {
		keys = skbaddr.hex
		values = len
		filter = len > 4096
	}
	3 {
		keys = skbaddr.hex
		values = len
		filter = len == 256
	}
	4 {
		keys = skbaddr.hex
		values = len
	}
	5 {
		keys = len
		values = common_preempt_count
	}
}

Link: https://lkml.kernel.org/r/162856125628.203126.15846930277378572120.stgit@devnote2



Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 8993665a

kernel/trace/trace_boot.c

+32 −9
Original line number Diff line number Diff line
@@ -324,7 +324,7 @@ trace_boot_hist_add_handlers(struct xbc_node *hnode, char **bufp, 
/*

 * Histogram boottime tracing syntax.

 *

 * ftrace.[instance.INSTANCE.]event.GROUP.EVENT.hist {

 * ftrace.[instance.INSTANCE.]event.GROUP.EVENT.hist[.N] {

 *	keys = <KEY>[,...]

 *	values = <VAL>[,...]

 *	sort = <SORT-KEY>[,...]
@@ -415,11 +415,37 @@ trace_boot_compose_hist_cmd(struct xbc_node *hnode, char *buf, size_t size) 


	return 0;

}



static void __init

trace_boot_init_histograms(struct trace_event_file *file,

			   struct xbc_node *hnode, char *buf, size_t size)

{

	struct xbc_node *node;

	const char *p;



	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. */

		if (trace_boot_compose_hist_cmd(node, buf, size) == 0) {

			if (trigger_process_regex(file, buf) < 0)

				pr_err("Failed to apply hist trigger: %s\n", buf);

		}

	}



	if (xbc_node_find_child(hnode, "keys")) {

		if (trace_boot_compose_hist_cmd(hnode, buf, size) == 0)

			if (trigger_process_regex(file, buf) < 0)

				pr_err("Failed to apply hist trigger: %s\n", buf);

	}

}

#else

static int __init

trace_boot_compose_hist_cmd(struct xbc_node *hnode, char *buf, size_t size)

static void __init

trace_boot_init_histograms(struct trace_event_file *file,

			   struct xbc_node *hnode, char *buf, size_t size)

{

	return -EOPNOTSUPP;

	/* do nothing */

}

#endif
@@ -465,11 +491,8 @@ trace_boot_init_one_event(struct trace_array *tr, struct xbc_node *gnode, 
				pr_err("Failed to apply an action: %s\n", buf);

		}

		anode = xbc_node_find_child(enode, "hist");

		if (anode &&

		    trace_boot_compose_hist_cmd(anode, buf, ARRAY_SIZE(buf)) == 0) {

			if (trigger_process_regex(file, buf) < 0)

				pr_err("Failed to apply hist trigger: %s\n", buf);

		}

		if (anode)

			trace_boot_init_histograms(file, anode, buf, ARRAY_SIZE(buf));

	} else if (xbc_node_find_value(enode, "actions", NULL))

		pr_err("Failed to apply event actions because CONFIG_HIST_TRIGGERS is not set.\n");