Re: [PATCH RFC] interconnect: Add interconnect_graph file to debugfs

[Bjorn Andersson <bjorn.andersson@linaro.org>]

On Wed 13 Nov 16:50 PST 2019, Leonard Crestez wrote:

> 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: Leonard Crestez <leonard.crestez@nxp.com>

Nice, I like it!

Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>

Regards,
Bjorn

> ---
>  drivers/interconnect/core.c | 66 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 66 insertions(+)
> 
> Example output as a github gist:
> https://gist.github.com/cdleonard/2f74a7efe74587e3d4b57cf7983b46a8
> 
> The qcs404 driver was hacked to probe on imx, the links to "0" seem to
> from incorrect trailing 0s on DEFINE_QNODE. Possibly fallout from
> switching to ARRAY_SIZE(__VA_ARGS__)?
> 
> I'm not sure that "graphviz" is allowed as an output format even in
> debugfs.
> 
> diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c
> index c498796adc07..07e91288c7f4 100644
> --- a/drivers/interconnect/core.c
> +++ b/drivers/interconnect/core.c
> @@ -92,10 +92,74 @@ static int icc_summary_show(struct seq_file *s, void *data)
>  
>  	return 0;
>  }
>  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);
>  }
>  
> @@ -800,10 +864,12 @@ EXPORT_SYMBOL_GPL(icc_provider_del);
>  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;
>  }
>  
>  static void __exit icc_exit(void)
>  {
> -- 
> 2.17.1
>