[PATCH v2 0/3] interconnect: Add basic tracepoints

[PATCH v2 0/3] interconnect: Add basic tracepoints

[Georgi Djakov]

The tracepoints can help with understanding the system behavior of a
given interconnect path when the consumer drivers change their bandwidth
demands. This might be interesting when we want to monitor the requested
interconnect bandwidth for each client driver. The paths may share the
same nodes and this will help to understand "who and when is requesting
what". All this is useful for subsystem drivers developers and may also
provide hints when optimizing the power and performance profile of the
system.

v2:
- Moved dev_name() into TP_fast_assign() to reduce cache footprint. (Steven)
- Added path name to traces (Bjorn)
- Added trace for path, device and ret. (Bjorn)

v1: https://lore.kernel.org/r/20191018140224.15087-1-georgi.djakov@linaro.org

Georgi Djakov (3):
  interconnect: Move internal structs into a separate file
  interconnect: Add a name to struct icc_path
  interconnect: Add basic tracepoints

 MAINTAINERS                         |  1 +
 drivers/interconnect/core.c         | 53 ++++++++-----------
 drivers/interconnect/internal.h     | 42 +++++++++++++++
 include/trace/events/interconnect.h | 81 +++++++++++++++++++++++++++++
 4 files changed, 147 insertions(+), 30 deletions(-)
 create mode 100644 drivers/interconnect/internal.h
 create mode 100644 include/trace/events/interconnect.h

[PATCH v2 1/3] interconnect: Move internal structs into a separate file

[Georgi Djakov]

Move the interconnect framework internal structs into a separate file,
so that it can be included and used by ftrace code. This will allow us
to expose some more useful information in the traces.

Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
---
 drivers/interconnect/core.c     | 30 ++-----------------------
 drivers/interconnect/internal.h | 40 +++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 28 deletions(-)
 create mode 100644 drivers/interconnect/internal.h

diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c
index 56cc4bacea5b..86ca6245fe6e 100644
--- a/drivers/interconnect/core.c
+++ b/drivers/interconnect/core.c
@@ -19,39 +19,13 @@
 #include <linux/of.h>
 #include <linux/overflow.h>
 
+#include "internal.h"
+
 static DEFINE_IDR(icc_idr);
 static LIST_HEAD(icc_providers);
 static DEFINE_MUTEX(icc_lock);
 static struct dentry *icc_debugfs_dir;
 
-/**
- * struct icc_req - constraints that are attached to each node
- * @req_node: entry in list of requests for the particular @node
- * @node: the interconnect node to which this constraint applies
- * @dev: reference to the device that sets the constraints
- * @tag: path tag (optional)
- * @avg_bw: an integer describing the average bandwidth in kBps
- * @peak_bw: an integer describing the peak bandwidth in kBps
- */
-struct icc_req {
-	struct hlist_node req_node;
-	struct icc_node *node;
-	struct device *dev;
-	u32 tag;
-	u32 avg_bw;
-	u32 peak_bw;
-};
-
-/**
- * struct icc_path - interconnect path structure
- * @num_nodes: number of hops (nodes)
- * @reqs: array of the requests applicable to this path of nodes
- */
-struct icc_path {
-	size_t num_nodes;
-	struct icc_req reqs[];
-};
-
 static void icc_summary_show_one(struct seq_file *s, struct icc_node *n)
 {
 	if (!n)
diff --git a/drivers/interconnect/internal.h b/drivers/interconnect/internal.h
new file mode 100644
index 000000000000..5853e8faf223
--- /dev/null
+++ b/drivers/interconnect/internal.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Interconnect framework internal structs
+ *
+ * Copyright (c) 2019, Linaro Ltd.
+ * Author: Georgi Djakov <georgi.djakov@linaro.org>
+ */
+
+#ifndef __DRIVERS_INTERCONNECT_INTERNAL_H
+#define __DRIVERS_INTERCONNECT_INTERNAL_H
+
+/**
+ * struct icc_req - constraints that are attached to each node
+ * @req_node: entry in list of requests for the particular @node
+ * @node: the interconnect node to which this constraint applies
+ * @dev: reference to the device that sets the constraints
+ * @tag: path tag (optional)
+ * @avg_bw: an integer describing the average bandwidth in kBps
+ * @peak_bw: an integer describing the peak bandwidth in kBps
+ */
+struct icc_req {
+	struct hlist_node req_node;
+	struct icc_node *node;
+	struct device *dev;
+	u32 tag;
+	u32 avg_bw;
+	u32 peak_bw;
+};
+
+/**
+ * struct icc_path - interconnect path structure
+ * @num_nodes: number of hops (nodes)
+ * @reqs: array of the requests applicable to this path of nodes
+ */
+struct icc_path {
+	size_t num_nodes;
+	struct icc_req reqs[];
+};
+
+#endif

[PATCH v2 2/3] interconnect: Add a name to struct icc_path

[Georgi Djakov]

When debugging interconnect things, it turned out that saving the path
name and including it in the traces is quite useful, especially for
devices with multiple paths.

For the path name we use the one specified in DT, or if we use platform
data, the name is based on the source and destination node names.

Suggested-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
---
 drivers/interconnect/core.c     | 18 +++++++++++++++---
 drivers/interconnect/internal.h |  2 ++
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c
index 86ca6245fe6e..df44ef713db5 100644
--- a/drivers/interconnect/core.c
+++ b/drivers/interconnect/core.c
@@ -356,9 +356,17 @@ struct icc_path *of_icc_get(struct device *dev, const char *name)
 
 	mutex_lock(&icc_lock);
 	path = path_find(dev, src_node, dst_node);
-	if (IS_ERR(path))
-		dev_err(dev, "%s: invalid path=%ld\n", __func__, PTR_ERR(path));
 	mutex_unlock(&icc_lock);
+	if (IS_ERR(path)) {
+		dev_err(dev, "%s: invalid path=%ld\n", __func__, PTR_ERR(path));
+		return path;
+	}
+
+	if (name)
+		path->name = kstrdup(name, GFP_KERNEL);
+	else
+		path->name = kasprintf(GFP_KERNEL, "%s-%s",
+				       src_node->name, dst_node->name);
 
 	return path;
 }
@@ -481,9 +489,12 @@ struct icc_path *icc_get(struct device *dev, const int src_id, const int dst_id)
 		goto out;
 
 	path = path_find(dev, src, dst);
-	if (IS_ERR(path))
+	if (IS_ERR(path)) {
 		dev_err(dev, "%s: invalid path=%ld\n", __func__, PTR_ERR(path));
+		goto out;
+	}
 
+	path->name = kasprintf(GFP_KERNEL, "%s-%s", src->name, dst->name);
 out:
 	mutex_unlock(&icc_lock);
 	return path;
@@ -519,6 +530,7 @@ void icc_put(struct icc_path *path)
 	}
 	mutex_unlock(&icc_lock);
 
+	kfree(path->name);
 	kfree(path);
 }
 EXPORT_SYMBOL_GPL(icc_put);
diff --git a/drivers/interconnect/internal.h b/drivers/interconnect/internal.h
index 5853e8faf223..bf18cb7239df 100644
--- a/drivers/interconnect/internal.h
+++ b/drivers/interconnect/internal.h
@@ -29,10 +29,12 @@ struct icc_req {
 
 /**
  * struct icc_path - interconnect path structure
+ * @name: a string name of the path (useful for ftrace)
  * @num_nodes: number of hops (nodes)
  * @reqs: array of the requests applicable to this path of nodes
  */
 struct icc_path {
+	const char *name;
 	size_t num_nodes;
 	struct icc_req reqs[];
 };

[PATCH v2 3/3] interconnect: Add basic tracepoints

[Georgi Djakov]

The tracepoints can help with understanding the system behavior of a
given interconnect path when the consumer drivers change their bandwidth
demands. This might be interesting when we want to monitor the requested
interconnect bandwidth for each client driver. The paths may share the
same nodes and this will help to understand "who and when is requesting
what". All this is useful for subsystem drivers developers and may also
provide hints when optimizing the power and performance profile of the
system.

Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
---
 MAINTAINERS                         |  1 +
 drivers/interconnect/core.c         |  7 +++
 include/trace/events/interconnect.h | 81 +++++++++++++++++++++++++++++
 3 files changed, 89 insertions(+)
 create mode 100644 include/trace/events/interconnect.h

diff --git a/MAINTAINERS b/MAINTAINERS
index a69e6db80c79..16f28fa515f2 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8522,6 +8522,7 @@ F:	drivers/interconnect/
 F:	include/dt-bindings/interconnect/
 F:	include/linux/interconnect-provider.h
 F:	include/linux/interconnect.h
+F:	include/trace/events/interconnect.h
 
 INVENSENSE MPU-3050 GYROSCOPE DRIVER
 M:	Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c
index df44ef713db5..15e11e22ddf7 100644
--- a/drivers/interconnect/core.c
+++ b/drivers/interconnect/core.c
@@ -26,6 +26,9 @@ static LIST_HEAD(icc_providers);
 static DEFINE_MUTEX(icc_lock);
 static struct dentry *icc_debugfs_dir;
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/interconnect.h>
+
 static void icc_summary_show_one(struct seq_file *s, struct icc_node *n)
 {
 	if (!n)
@@ -435,6 +438,8 @@ int icc_set_bw(struct icc_path *path, u32 avg_bw, u32 peak_bw)
 
 		/* aggregate requests for this node */
 		aggregate_requests(node);
+
+		trace_icc_set_bw(path, node, i, avg_bw, peak_bw);
 	}
 
 	ret = apply_constraints(path);
@@ -453,6 +458,8 @@ int icc_set_bw(struct icc_path *path, u32 avg_bw, u32 peak_bw)
 
 	mutex_unlock(&icc_lock);
 
+	trace_icc_set_bw_end(path, ret);
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(icc_set_bw);
diff --git a/include/trace/events/interconnect.h b/include/trace/events/interconnect.h
new file mode 100644
index 000000000000..64b646aa7bd3
--- /dev/null
+++ b/include/trace/events/interconnect.h
@@ -0,0 +1,81 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2019, Linaro Ltd.
+ * Author: Georgi Djakov <georgi.djakov@linaro.org>
+ */
+
+#if !defined(_TRACE_INTERCONNECT_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_INTERCONNECT_H
+
+#include <linux/tracepoint.h>
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM interconnect
+
+#include "../../../drivers/interconnect/internal.h"
+
+TRACE_EVENT(icc_set_bw,
+
+	TP_PROTO(struct icc_path *p, struct icc_node *n, int i,
+		 u32 avg_bw, u32 peak_bw),
+
+	TP_ARGS(p, n, i, avg_bw, peak_bw),
+
+	TP_STRUCT__entry(
+		__string(path_name, p->name)
+		__string(dev, dev_name(p->reqs[i].dev))
+		__string(node_name, n->name)
+		__field(u32, avg_bw)
+		__field(u32, peak_bw)
+		__field(u32, node_avg_bw)
+		__field(u32, node_peak_bw)
+	),
+
+	TP_fast_assign(
+		__assign_str(path_name, p->name);
+		__assign_str(dev, dev_name(p->reqs[i].dev));
+		__assign_str(node_name, n->name);
+		__entry->avg_bw = avg_bw;
+		__entry->peak_bw = peak_bw;
+		__entry->node_avg_bw = n->avg_bw;
+		__entry->node_peak_bw = n->peak_bw;
+	),
+
+	TP_printk("path=%s dev=%s node=%s avg_bw=%u peak_bw=%u agg_avg=%u agg_peak=%u",
+		  __get_str(path_name),
+		  __get_str(dev),
+		  __get_str(node_name),
+		  __entry->avg_bw,
+		  __entry->peak_bw,
+		  __entry->node_avg_bw,
+		  __entry->node_peak_bw)
+);
+
+TRACE_EVENT(icc_set_bw_end,
+
+	TP_PROTO(struct icc_path *p, int ret),
+
+	TP_ARGS(p, ret),
+
+	TP_STRUCT__entry(
+		__string(path_name, p->name)
+		__string(dev, dev_name(p->reqs[0].dev))
+		__field(int, ret)
+	),
+
+	TP_fast_assign(
+		__assign_str(path_name, p->name);
+		__assign_str(dev, dev_name(p->reqs[0].dev));
+		__entry->ret = ret;
+	),
+
+	TP_printk("path=%s dev=%s ret=%d",
+		  __get_str(path_name),
+		  __get_str(dev),
+		  __entry->ret)
+);
+
+#endif /* _TRACE_INTERCONNECT_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>

Re: [PATCH v2 3/3] interconnect: Add basic tracepoints

[Steven Rostedt]

On Fri,  1 Nov 2019 15:00:31 +0200
Georgi Djakov <georgi.djakov@linaro.org> wrote:

> diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c
> index df44ef713db5..15e11e22ddf7 100644
> --- a/drivers/interconnect/core.c
> +++ b/drivers/interconnect/core.c
> @@ -26,6 +26,9 @@ static LIST_HEAD(icc_providers);
>  static DEFINE_MUTEX(icc_lock);
>  static struct dentry *icc_debugfs_dir;
>  
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/interconnect.h>
> +
>  static void icc_summary_show_one(struct seq_file *s, struct icc_node *n)
>  {
>  	if (!n)
> @@ -435,6 +438,8 @@ int icc_set_bw(struct icc_path *path, u32 avg_bw, u32 peak_bw)
>  
>  		/* aggregate requests for this node */
>  		aggregate_requests(node);
> +
> +		trace_icc_set_bw(path, node, i, avg_bw, peak_bw);
>  	}
>  
>  	ret = apply_constraints(path);
> @@ -453,6 +458,8 @@ int icc_set_bw(struct icc_path *path, u32 avg_bw, u32 peak_bw)
>  
>  	mutex_unlock(&icc_lock);
>  
> +	trace_icc_set_bw_end(path, ret);
> +
>  	return ret;
>  }
>  EXPORT_SYMBOL_GPL(icc_set_bw);
> diff --git a/include/trace/events/interconnect.h b/include/trace/events/interconnect.h
> new file mode 100644
> index 000000000000..64b646aa7bd3
> --- /dev/null
> +++ b/include/trace/events/interconnect.h
> @@ -0,0 +1,81 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2019, Linaro Ltd.
> + * Author: Georgi Djakov <georgi.djakov@linaro.org>
> + */
> +
> +#if !defined(_TRACE_INTERCONNECT_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_INTERCONNECT_H
> +
> +#include <linux/tracepoint.h>
> +
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM interconnect
> +
> +#include "../../../drivers/interconnect/internal.h"

Ug.

I would recommend placing this file in with drivers/interconnect, and
call it simply trace.h, or interconnect_trace.h. Then you can include
"internal.h" nicely.

To do so, you need to add to drivers/interconnect/Makefile:

 CFLAGS_core.o := -I$(src)

To have core.c include this file.

Rest looks fine.

-- Steve


> +
> +TRACE_EVENT(icc_set_bw,
> +
> +	TP_PROTO(struct icc_path *p, struct icc_node *n, int i,
> +		 u32 avg_bw, u32 peak_bw),
> +
> +	TP_ARGS(p, n, i, avg_bw, peak_bw),
> +
> +	TP_STRUCT__entry(
> +		__string(path_name, p->name)
> +		__string(dev, dev_name(p->reqs[i].dev))
> +		__string(node_name, n->name)
> +		__field(u32, avg_bw)
> +		__field(u32, peak_bw)
> +		__field(u32, node_avg_bw)
> +		__field(u32, node_peak_bw)
> +	),
> +
> +	TP_fast_assign(
> +		__assign_str(path_name, p->name);
> +		__assign_str(dev, dev_name(p->reqs[i].dev));
> +		__assign_str(node_name, n->name);
> +		__entry->avg_bw = avg_bw;
> +		__entry->peak_bw = peak_bw;
> +		__entry->node_avg_bw = n->avg_bw;
> +		__entry->node_peak_bw = n->peak_bw;
> +	),
> +
> +	TP_printk("path=%s dev=%s node=%s avg_bw=%u peak_bw=%u agg_avg=%u agg_peak=%u",
> +		  __get_str(path_name),
> +		  __get_str(dev),
> +		  __get_str(node_name),
> +		  __entry->avg_bw,
> +		  __entry->peak_bw,
> +		  __entry->node_avg_bw,
> +		  __entry->node_peak_bw)
> +);
> +
> +TRACE_EVENT(icc_set_bw_end,
> +
> +	TP_PROTO(struct icc_path *p, int ret),
> +
> +	TP_ARGS(p, ret),
> +
> +	TP_STRUCT__entry(
> +		__string(path_name, p->name)
> +		__string(dev, dev_name(p->reqs[0].dev))
> +		__field(int, ret)
> +	),
> +
> +	TP_fast_assign(
> +		__assign_str(path_name, p->name);
> +		__assign_str(dev, dev_name(p->reqs[0].dev));
> +		__entry->ret = ret;
> +	),
> +
> +	TP_printk("path=%s dev=%s ret=%d",
> +		  __get_str(path_name),
> +		  __get_str(dev),
> +		  __entry->ret)
> +);
> +
> +#endif /* _TRACE_INTERCONNECT_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>