Re: [PATCH] clk: Add tracepoints for hardware operations

[Steven Rostedt]

On Mon, 30 Jun 2014 16:56:39 -0700
Stephen Boyd <sboyd@xxxxxxxxxxxxxx> wrote:

> It's useful to have tracepoints around operations that change the
> hardware state so that we can debug clock hardware performance
> and operations. Three basic types of events are supported: on/off
> events for enable, disable, prepare, unprepare that only record
> an event and a clock name, rate changing events for
> clk_set_rate() and parent changing events for clk_set_parent().
> 
> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
> ---
> 
> I see that there are tracepoints for clock_enable/clock_set_rate
> in events/power.h but those look to be unused and they also
> take cpu_id which seems odd. I'd rather we just make a new set of
> events for the common clock framework instead and add the "_complete"
> set of events so we know when things have completed.
> 
>  drivers/clk/clk.c          |  28 ++++++++
>  include/trace/events/clk.h | 165 +++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 193 insertions(+)
>  create mode 100644 include/trace/events/clk.h
> 
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index 8b73edef151d..f8bf69df3210 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -21,6 +21,9 @@
>  #include <linux/init.h>
>  #include <linux/sched.h>
>  
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/clk.h>
> +
>  #include "clk.h"
>  
>  static DEFINE_SPINLOCK(enable_lock);
> @@ -483,10 +486,12 @@ static void clk_unprepare_unused_subtree(struct clk *clk)
>  		return;
>  
>  	if (__clk_is_prepared(clk)) {
> +		trace_clk_unprepare(clk);

Does it make sense to do these when clk->ops->unprepared_unused or
uprepare is not set?

You can use DEFINE_EVENT_CONDITIONAL() and add as condition:

   clk->ops->unprepared_unused || clk->ops->unprepare


>  		if (clk->ops->unprepare_unused)
>  			clk->ops->unprepare_unused(clk->hw);
>  		else if (clk->ops->unprepare)
>  			clk->ops->unprepare(clk->hw);
> +		trace_clk_unprepare_complete(clk);
>  	}
>  }
>  
> @@ -516,10 +521,12 @@ static void clk_disable_unused_subtree(struct clk *clk)
>  	 * back to .disable
>  	 */
>  	if (__clk_is_enabled(clk)) {
> +		trace_clk_disable(clk);

Same here.

>  		if (clk->ops->disable_unused)
>  			clk->ops->disable_unused(clk->hw);
>  		else if (clk->ops->disable)
>  			clk->ops->disable(clk->hw);
> +		trace_clk_disable_complete(clk);
>  	}
>  
>  unlock_out:
> @@ -802,9 +809,13 @@ void __clk_unprepare(struct clk *clk)
>  
>  	WARN_ON(clk->enable_count > 0);
>  
> +	trace_clk_unprepare(clk);
> +

And here.

>  	if (clk->ops->unprepare)
>  		clk->ops->unprepare(clk->hw);
>  
> +	trace_clk_unprepare_complete(clk);
> +
>  	__clk_unprepare(clk->parent);
>  }
>  
> @@ -842,6 +853,8 @@ int __clk_prepare(struct clk *clk)
>  		if (ret)
>  			return ret;
>  
> +		trace_clk_prepare(clk);

A pattern is happening.

> +
>  		if (clk->ops->prepare) {
>  			ret = clk->ops->prepare(clk->hw);
>  			if (ret) {
> @@ -849,6 +862,8 @@ int __clk_prepare(struct clk *clk)
>  				return ret;
>  			}
>  		}
> +
> +		trace_clk_prepare_complete(clk);
>  	}
>  
>  	clk->prepare_count++;
> @@ -891,9 +906,13 @@ static void __clk_disable(struct clk *clk)
>  	if (--clk->enable_count > 0)
>  		return;
>  
> +	trace_clk_disable(clk);

ditto

> +
>  	if (clk->ops->disable)
>  		clk->ops->disable(clk->hw);
>  
> +	trace_clk_disable_complete(clk);
> +
>  	__clk_disable(clk->parent);
>  }
>  
> @@ -938,6 +957,7 @@ static int __clk_enable(struct clk *clk)
>  		if (ret)
>  			return ret;
>  
> +		trace_clk_enable(clk);

ditto

>  		if (clk->ops->enable) {
>  			ret = clk->ops->enable(clk->hw);
>  			if (ret) {
> @@ -945,6 +965,7 @@ static int __clk_enable(struct clk *clk)
>  				return ret;

It may make even more sense to add the tracepoints within the if
statement. Especially if you have a return on error.

>  			}
>  		}
> +		trace_clk_enable_complete(clk);
>  	}
>  
>  	clk->enable_count++;
> @@ -1241,6 +1262,8 @@ static struct clk *__clk_set_parent_before(struct clk *clk, struct clk *parent)
>  	unsigned long flags;
>  	struct clk *old_parent = clk->parent;
>  
> +	trace_clk_set_parent(clk, parent);
> +
>  	/*
>  	 * Migrate prepare state between parents and prevent race with
>  	 * clk_enable().
> @@ -1285,6 +1308,7 @@ static void __clk_set_parent_after(struct clk *clk, struct clk *parent,
>  		__clk_unprepare(old_parent);
>  	}
>  
> +	trace_clk_set_parent_complete(clk, parent);
>  	/* update debugfs with new clk tree topology */
>  	clk_debug_reparent(clk, parent);
>  }
> @@ -1507,6 +1531,8 @@ static void clk_change_rate(struct clk *clk)
>  	else if (clk->parent)
>  		best_parent_rate = clk->parent->rate;
>  
> +	trace_clk_set_rate(clk, clk->new_rate);
> +
>  	if (clk->new_parent && clk->new_parent != clk->parent) {
>  		old_parent = __clk_set_parent_before(clk, clk->new_parent);
>  
> @@ -1525,6 +1551,8 @@ static void clk_change_rate(struct clk *clk)
>  	if (!skip_set_rate && clk->ops->set_rate)
>  		clk->ops->set_rate(clk->hw, clk->new_rate, best_parent_rate);
>  
> +	trace_clk_set_rate_complete(clk, clk->new_rate);
> +
>  	clk->rate = clk_recalc(clk, best_parent_rate);
>  
>  	if (clk->notifier_count && old_rate != clk->rate)
> diff --git a/include/trace/events/clk.h b/include/trace/events/clk.h
> new file mode 100644
> index 000000000000..8523adce0f73
> --- /dev/null
> +++ b/include/trace/events/clk.h
> @@ -0,0 +1,165 @@
> +/*
> + * Copyright (c) 2014, The Linux Foundation. All rights reserved.
> + *
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM clk
> +
> +#if !defined(_TRACE_CLK_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_CLK_H
> +
> +#include <linux/tracepoint.h>
> +
> +struct clk;
> +
> +DECLARE_EVENT_CLASS(clk,
> +
> +	TP_PROTO(struct clk *clk),
> +
> +	TP_ARGS(clk),
> +
> +	TP_STRUCT__entry(
> +		__string(        name,           __clk_get_name(clk)       )
> +	),
> +
> +	TP_fast_assign(
> +		__assign_str(name, __clk_get_name(clk));
> +	),
> +
> +	TP_printk("%s", __get_str(name))
> +);
> +
> +DEFINE_EVENT(clk, clk_enable,
> +
> +	TP_PROTO(struct clk *clk),
> +
> +	TP_ARGS(clk)
> +);
> +
> +DEFINE_EVENT(clk, clk_enable_complete,
> +
> +	TP_PROTO(struct clk *clk),
> +
> +	TP_ARGS(clk)
> +);
> +
> +DEFINE_EVENT(clk, clk_disable,
> +
> +	TP_PROTO(struct clk *clk),
> +
> +	TP_ARGS(clk)
> +);
> +
> +DEFINE_EVENT(clk, clk_disable_complete,
> +
> +	TP_PROTO(struct clk *clk),
> +
> +	TP_ARGS(clk)
> +);
> +
> +DEFINE_EVENT(clk, clk_prepare,
> +
> +	TP_PROTO(struct clk *clk),
> +
> +	TP_ARGS(clk)
> +);
> +
> +DEFINE_EVENT(clk, clk_prepare_complete,
> +
> +	TP_PROTO(struct clk *clk),
> +
> +	TP_ARGS(clk)
> +);
> +
> +DEFINE_EVENT(clk, clk_unprepare,
> +
> +	TP_PROTO(struct clk *clk),
> +
> +	TP_ARGS(clk)

For example, you would make the above DEFINE_EVENT_CONDITION()
and then add

 TP_CONDITION(clk->ops->unprepared_unused || clk->ops->unprepare)

You can look at include/trace/f2fs.h for an example.

-- Steve


> +);
> +
> +DEFINE_EVENT(clk, clk_unprepare_complete,
> +
> +	TP_PROTO(struct clk *clk),
> +
> +	TP_ARGS(clk)
> +);
> +
> +DECLARE_EVENT_CLASS(clk_rate,
> +
> +	TP_PROTO(struct clk *clk, unsigned long rate),
> +
> +	TP_ARGS(clk, rate),
> +
> +	TP_STRUCT__entry(
> +		__string(        name,           __clk_get_name(clk)       )
> +		__field(unsigned long,           rate                      )
> +	),
> +
> +	TP_fast_assign(
> +		__assign_str(name, __clk_get_name(clk));
> +		__entry->rate = rate;
> +	),
> +
> +	TP_printk("%s %lu", __get_str(name), (unsigned long)__entry->rate)
> +);
> +
> +DEFINE_EVENT(clk_rate, clk_set_rate,
> +
> +	TP_PROTO(struct clk *clk, unsigned long rate),
> +
> +	TP_ARGS(clk, rate)
> +);
> +
> +DEFINE_EVENT(clk_rate, clk_set_rate_complete,
> +
> +	TP_PROTO(struct clk *clk, unsigned long rate),
> +
> +	TP_ARGS(clk, rate)
> +);
> +
> +DECLARE_EVENT_CLASS(clk_parent,
> +
> +	TP_PROTO(struct clk *clk, struct clk *parent),
> +
> +	TP_ARGS(clk, parent),
> +
> +	TP_STRUCT__entry(
> +		__string(        name,           __clk_get_name(clk)       )
> +		__string(        pname,          __clk_get_name(parent)    )
> +	),
> +
> +	TP_fast_assign(
> +		__assign_str(name, __clk_get_name(clk));
> +		__assign_str(pname, __clk_get_name(parent));
> +	),
> +
> +	TP_printk("%s %s", __get_str(name), __get_str(pname))
> +);
> +
> +DEFINE_EVENT(clk_parent, clk_set_parent,
> +
> +	TP_PROTO(struct clk *clk, struct clk *parent),
> +
> +	TP_ARGS(clk, parent)
> +);
> +
> +DEFINE_EVENT(clk_parent, clk_set_parent_complete,
> +
> +	TP_PROTO(struct clk *clk, struct clk *parent),
> +
> +	TP_ARGS(clk, parent)
> +);
> +
> +#endif /* _TRACE_CLK_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>

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