[v3,0/3] interconnect: Add basic tracepoints

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.

v3: https://lore.kernel.org/r/20191101130031.27996-1-georgi.djakov@linaro.org
- In order to avoid #including a file with relative path, move the trace.h
  header into drivers/interconnect/. (Steven)

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

 drivers/interconnect/Makefile   |  1 +
 drivers/interconnect/core.c     | 55 +++++++++-----------
 drivers/interconnect/internal.h | 42 +++++++++++++++
 drivers/interconnect/trace.h    | 90 +++++++++++++++++++++++++++++++++
 4 files changed, 157 insertions(+), 31 deletions(-)
 create mode 100644 drivers/interconnect/internal.h
 create mode 100644 drivers/interconnect/trace.h

On Fri, 22 Nov 2019 17:27:12 +0200
Georgi Djakov <georgi.djakov@linaro.org> wrote:
> index 28f2ab0824d5..725029ae7a2c 100644

> --- a/drivers/interconnect/Makefile

> +++ b/drivers/interconnect/Makefile

> @@ -1,5 +1,6 @@

>  # SPDX-License-Identifier: GPL-2.0

>  

> +CFLAGS_core.o				:= -I$(src)

>  icc-core-objs				:= core.o

>  

>  obj-$(CONFIG_INTERCONNECT)		+= icc-core.o

> diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c

> index 1ddad8ef3cf0..b218a2609f6b 100644

> --- a/drivers/interconnect/core.c

> +++ b/drivers/interconnect/core.c

> @@ -19,6 +19,9 @@

>  #include <linux/of.h>

>  #include <linux/overflow.h>

>  

> +#define CREATE_TRACE_POINTS

> +#include "trace.h"

> +


You may want to move this below the include of internal.h, as you don't
want CREATE_TRACE_POINTS defined when including any other header, or it
can cause issues if that header has some tracepoint header inside it.

It may not be the case now, but could cause for headaches in the
future, if other headers get included in internal.h.

>  #include "internal.h"

>  

>  static DEFINE_IDR(icc_idr);

> @@ -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/drivers/interconnect/trace.h b/drivers/interconnect/trace.h

> new file mode 100644

> index 000000000000..d2421bf7b389

> --- /dev/null

> +++ b/drivers/interconnect/trace.h

> @@ -0,0 +1,90 @@

> +/* SPDX-License-Identifier: GPL-2.0 */

> +/*

> + * Interconnect framework tracepoints

> + * Copyright (c) 2019, Linaro Ltd.

> + * Author: Georgi Djakov <georgi.djakov@linaro.org>

> + */

> +

> +#undef TRACE_SYSTEM

> +#define TRACE_SYSTEM interconnect

> +

> +#if !defined(_TRACE_INTERCONNECT_H) || defined(TRACE_HEADER_MULTI_READ)

> +#define _TRACE_INTERCONNECT_H

> +

> +#include <linux/interconnect.h>

> +#include <linux/tracepoint.h>

> +

> +#include "internal.h"


And you include it here too, perhaps it is best not to have it here,
and then just have it before trace.h is called?

The rest looks good. Besides the comments above:

Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>


-- 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 */

> +

> +#undef TRACE_INCLUDE_PATH

> +#define TRACE_INCLUDE_PATH .

> +

> +#undef TRACE_INCLUDE_FILE

> +#define TRACE_INCLUDE_FILE trace

> +

> +#include <trace/define_trace.h>