linux-kernel - Re: [PATCH v4 3/3] interconnect: Add basic tracepoints

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Date:   Thu, 28 Nov 2019 10:08:09 -0800
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Georgi Djakov <georgi.djakov@...aro.org>
Cc:     linux-pm@...r.kernel.org, rostedt@...dmis.org, mingo@...hat.com,
        vincent.guittot@...aro.org, daidavid1@...eaurora.org,
        okukatla@...eaurora.org, evgreen@...omium.org, mka@...omium.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 3/3] interconnect: Add basic tracepoints

On Thu 28 Nov 06:18 PST 2019, Georgi Djakov wrote:

> 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.
> 
> Reviewed-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
> Signed-off-by: Georgi Djakov <georgi.djakov@...aro.org>

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

> ---
>  drivers/interconnect/Makefile |  1 +
>  drivers/interconnect/core.c   |  7 +++
>  drivers/interconnect/trace.h  | 88 +++++++++++++++++++++++++++++++++++
>  3 files changed, 96 insertions(+)
>  create mode 100644 drivers/interconnect/trace.h
> 
> diff --git a/drivers/interconnect/Makefile b/drivers/interconnect/Makefile
> 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 c9e16bc1331e..0e4852feb395 100644
> --- a/drivers/interconnect/core.c
> +++ b/drivers/interconnect/core.c
> @@ -21,6 +21,9 @@
>  
>  #include "internal.h"
>  
> +#define CREATE_TRACE_POINTS
> +#include "trace.h"
> +
>  static DEFINE_IDR(icc_idr);
>  static LIST_HEAD(icc_providers);
>  static DEFINE_MUTEX(icc_lock);
> @@ -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..3d668ff566bf
> --- /dev/null
> +++ b/drivers/interconnect/trace.h
> @@ -0,0 +1,88 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Interconnect framework tracepoints
> + * Copyright (c) 2019, Linaro Ltd.
> + * Author: Georgi Djakov <georgi.djakov@...aro.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>
> +
> +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>