Commit 1a0013c6 authored by Leonard Crestez's avatar Leonard Crestez Committed by Georgi Djakov
Browse files

interconnect: Add interconnect_graph file to debugfs 



The interconnect graphs can be difficult to understand and the current
"interconnect_summary" file doesn't even display links in any way.

Add a new "interconnect_graph" file to debugfs in the graphviz "dot"
format which describes interconnect providers, nodes and links.

The file is human-readable and can be visualized by piping through
graphviz. Example:

ssh $TARGET cat /sys/kernel/debug/interconnect/interconnect_graph \
	| dot -Tsvg > interconnect_graph.svg

Signed-off-by: default avatarLeonard Crestez <leonard.crestez@nxp.com>
Reviewed-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: default avatarBjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: default avatarGeorgi Djakov <georgi.djakov@linaro.org>
parent b92c35e1

Documentation/driver-api/interconnect.rst

+22 −0
Original line number Diff line number Diff line
@@ -91,3 +91,25 @@ Interconnect consumers are the clients which use the interconnect APIs to 
get paths between endpoints and set their bandwidth/latency/QoS requirements

for these interconnect paths.  These interfaces are not currently

documented.



Interconnect debugfs interfaces

-------------------------------



Like several other subsystems interconnect will create some files for debugging

and introspection. Files in debugfs are not considered ABI so application

software shouldn't rely on format details change between kernel versions.



``/sys/kernel/debug/interconnect/interconnect_summary``:



Show all interconnect nodes in the system with their aggregated bandwidth

request. Indented under each node show bandwidth requests from each device.



``/sys/kernel/debug/interconnect/interconnect_graph``:



Show the interconnect graph in the graphviz dot format. It shows all

interconnect nodes and links in the system and groups together nodes from the

same provider as subgraphs. The format is human-readable and can also be piped

through dot to generate diagrams in many graphical formats::



        $ cat /sys/kernel/debug/interconnect/interconnect_graph | \

                dot -Tsvg > interconnect_graph.svg

drivers/interconnect/core.c

+66 −0
Original line number Diff line number Diff line
@@ -71,6 +71,70 @@ static int icc_summary_show(struct seq_file *s, void *data) 
}

DEFINE_SHOW_ATTRIBUTE(icc_summary);



static void icc_graph_show_link(struct seq_file *s, int level,

				struct icc_node *n, struct icc_node *m)

{

	seq_printf(s, "%s\"%d:%s\" -> \"%d:%s\"\n",

		   level == 2 ? "\t\t" : "\t",

		   n->id, n->name, m->id, m->name);

}



static void icc_graph_show_node(struct seq_file *s, struct icc_node *n)

{

	seq_printf(s, "\t\t\"%d:%s\" [label=\"%d:%s",

		   n->id, n->name, n->id, n->name);

	seq_printf(s, "\n\t\t\t|avg_bw=%ukBps", n->avg_bw);

	seq_printf(s, "\n\t\t\t|peak_bw=%ukBps", n->peak_bw);

	seq_puts(s, "\"]\n");

}



static int icc_graph_show(struct seq_file *s, void *data)

{

	struct icc_provider *provider;

	struct icc_node *n;

	int cluster_index = 0;

	int i;



	seq_puts(s, "digraph {\n\trankdir = LR\n\tnode [shape = record]\n");

	mutex_lock(&icc_lock);



	/* draw providers as cluster subgraphs */

	cluster_index = 0;

	list_for_each_entry(provider, &icc_providers, provider_list) {

		seq_printf(s, "\tsubgraph cluster_%d {\n", ++cluster_index);

		if (provider->dev)

			seq_printf(s, "\t\tlabel = \"%s\"\n",

				   dev_name(provider->dev));



		/* draw nodes */

		list_for_each_entry(n, &provider->nodes, node_list)

			icc_graph_show_node(s, n);



		/* draw internal links */

		list_for_each_entry(n, &provider->nodes, node_list)

			for (i = 0; i < n->num_links; ++i)

				if (n->provider == n->links[i]->provider)

					icc_graph_show_link(s, 2, n,

							    n->links[i]);



		seq_puts(s, "\t}\n");

	}



	/* draw external links */

	list_for_each_entry(provider, &icc_providers, provider_list)

		list_for_each_entry(n, &provider->nodes, node_list)

			for (i = 0; i < n->num_links; ++i)

				if (n->provider != n->links[i]->provider)

					icc_graph_show_link(s, 1, n,

							    n->links[i]);



	mutex_unlock(&icc_lock);

	seq_puts(s, "}");



	return 0;

}

DEFINE_SHOW_ATTRIBUTE(icc_graph);



static struct icc_node *node_find(const int id)

{

	return idr_find(&icc_idr, id);
@@ -827,6 +891,8 @@ static int __init icc_init(void) 
	icc_debugfs_dir = debugfs_create_dir("interconnect", NULL);

	debugfs_create_file("interconnect_summary", 0444,

			    icc_debugfs_dir, NULL, &icc_summary_fops);

	debugfs_create_file("interconnect_graph", 0444,

			    icc_debugfs_dir, NULL, &icc_graph_fops);

	return 0;

}

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