Re: [PATCH v2 3/3] remoteproc: Add ftrace events to trace lifecycle of remoteprocs

[Mathieu Poirier]

On Mon, Nov 16, 2020 at 01:44:44PM -0800, Rishabh Bhatnagar wrote:
> Add trace events to trace bootup/shutdown/recovery of remote
> processors. These events are useful in analyzing the time
> spent in each step in the life cycle and can be used for
> performace analysis. Also these serve as standard checkpoints
> in debugging.
> 
> Signed-off-by: Rishabh Bhatnagar <rishabhb@xxxxxxxxxxxxxx>
> ---
>  drivers/remoteproc/remoteproc_core.c | 19 +++++++-
>  include/trace/events/remoteproc.h    | 91 ++++++++++++++++++++++++++++++++++++
>  2 files changed, 109 insertions(+), 1 deletion(-)
>  create mode 100644 include/trace/events/remoteproc.h
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index dab2c0f..39da409 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -42,6 +42,9 @@
>  
>  #include "remoteproc_internal.h"
>  
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/remoteproc.h>
> +
>  #define HIGH_BITS_MASK 0xFFFFFFFF00000000ULL
>  
>  static DEFINE_MUTEX(rproc_list_mutex);
> @@ -1164,6 +1167,7 @@ static int rproc_prepare_subdevices(struct rproc *rproc)
>  	struct rproc_subdev *subdev;
>  	int ret;
>  
> +	trace_rproc_subdevices("Prepare subdevices", rproc->name);

I wouldn't add this to the core - after a while they become part of the ABI and
we can't move things around.  I suppose they can stay in platform drivers but
even that is going against the general trend in the kernel community to avoid them at
all.  To me this should remain out of tree code but Bjorn will make the call.

Thanks,
Mathieu

>  	list_for_each_entry(subdev, &rproc->subdevs, node) {
>  		if (subdev->prepare) {
>  			ret = subdev->prepare(subdev);
> @@ -1188,6 +1192,7 @@ static int rproc_start_subdevices(struct rproc *rproc)
>  	struct rproc_subdev *subdev;
>  	int ret;
>  
> +	trace_rproc_subdevices("Start subdevices", rproc->name);
>  	list_for_each_entry(subdev, &rproc->subdevs, node) {
>  		if (subdev->start) {
>  			ret = subdev->start(subdev);
> @@ -1211,6 +1216,7 @@ static void rproc_stop_subdevices(struct rproc *rproc, bool crashed)
>  {
>  	struct rproc_subdev *subdev;
>  
> +	trace_rproc_subdevices("Stop subdevices", rproc->name);
>  	list_for_each_entry_reverse(subdev, &rproc->subdevs, node) {
>  		if (subdev->stop)
>  			subdev->stop(subdev, crashed);
> @@ -1221,6 +1227,7 @@ static void rproc_unprepare_subdevices(struct rproc *rproc)
>  {
>  	struct rproc_subdev *subdev;
>  
> +	trace_rproc_subdevices("Unprepare subdevices", rproc->name);
>  	list_for_each_entry_reverse(subdev, &rproc->subdevs, node) {
>  		if (subdev->unprepare)
>  			subdev->unprepare(subdev);
> @@ -1357,6 +1364,7 @@ static int rproc_start(struct rproc *rproc, const struct firmware *fw)
>  	struct device *dev = &rproc->dev;
>  	int ret;
>  
> +	trace_rproc_boot("loading firmware segments into memory", rproc->name);
>  	/* load the ELF segments to memory */
>  	ret = rproc_load_segments(rproc, fw);
>  	if (ret) {
> @@ -1385,6 +1393,7 @@ static int rproc_start(struct rproc *rproc, const struct firmware *fw)
>  		goto reset_table_ptr;
>  	}
>  
> +	trace_rproc_boot("starting remoteproc", rproc->name);
>  	/* power up the remote processor */
>  	ret = rproc->ops->start(rproc);
>  	if (ret) {
> @@ -1402,6 +1411,7 @@ static int rproc_start(struct rproc *rproc, const struct firmware *fw)
>  
>  	rproc->state = RPROC_RUNNING;
>  
> +	trace_rproc_boot("remoteproc is up", rproc->name);
>  	dev_info(dev, "remote processor %s is now up\n", rproc->name);
>  
>  	return 0;
> @@ -1648,6 +1658,7 @@ static int rproc_stop(struct rproc *rproc, bool crashed)
>  	/* the installed resource table is no longer accessible */
>  	rproc->table_ptr = rproc->cached_table;
>  
> +	trace_rproc_shutdown("Stopping the remoteproc", rproc->name);
>  	/* power off the remote processor */
>  	ret = rproc->ops->stop(rproc);
>  	if (ret) {
> @@ -1697,6 +1708,7 @@ int rproc_trigger_recovery(struct rproc *rproc)
>  	if (rproc->state != RPROC_CRASHED)
>  		goto unlock_mutex;
>  
> +	trace_rproc_recovery("Recover remoteproc", rproc->name);
>  	dev_err(dev, "recovering %s\n", rproc->name);
>  
>  	ret = rproc_stop(rproc, true);
> @@ -1716,6 +1728,7 @@ int rproc_trigger_recovery(struct rproc *rproc)
>  	/* boot the remote processor up again */
>  	ret = rproc_start(rproc, firmware_p);
>  
> +	trace_rproc_recovery("Recovery completed", rproc->name);
>  	release_firmware(firmware_p);
>  
>  unlock_mutex:
> @@ -1796,6 +1809,7 @@ int rproc_boot(struct rproc *rproc)
>  	/* skip the boot or attach process if rproc is already powered up */
>  	if (atomic_inc_return(&rproc->power) > 1) {
>  		ret = 0;
> +		trace_rproc_boot("Incrementing ref count and exiting", rproc->name);
>  		goto unlock_mutex;
>  	}
>  
> @@ -1804,6 +1818,7 @@ int rproc_boot(struct rproc *rproc)
>  
>  		ret = rproc_actuate(rproc);
>  	} else {
> +		trace_rproc_boot("requesting firmware", rproc->name);
>  		dev_info(dev, "powering up %s\n", rproc->name);
>  
>  		/* load firmware */
> @@ -1858,8 +1873,10 @@ void rproc_shutdown(struct rproc *rproc)
>  	}
>  
>  	/* if the remote proc is still needed, bail out */
> -	if (!atomic_dec_and_test(&rproc->power))
> +	if (!atomic_dec_and_test(&rproc->power)) {
> +		trace_rproc_shutdown("Decrementing ref count and exiting", rproc->name);
>  		goto out;
> +	}
>  
>  	ret = rproc_stop(rproc, false);
>  	if (ret) {
> diff --git a/include/trace/events/remoteproc.h b/include/trace/events/remoteproc.h
> new file mode 100644
> index 0000000..341bf4b
> --- /dev/null
> +++ b/include/trace/events/remoteproc.h
> @@ -0,0 +1,91 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (c) 2020, The Linux Foundation. All rights reserved.
> + */
> +
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM remoteproc
> +
> +#if !defined(_TRACE_REMOTEPROC_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_REMOTEPROC_H
> +
> +#include <linux/tracepoint.h>
> +
> +TRACE_EVENT(rproc_boot,
> +
> +	TP_PROTO(const char *event, const char *rproc_name),
> +
> +	TP_ARGS(event, rproc_name),
> +
> +	TP_STRUCT__entry(
> +		__string(event, event)
> +		__string(rproc_name, rproc_name)
> +	),
> +
> +	TP_fast_assign(
> +		__assign_str(event, event);
> +		__assign_str(rproc_name, rproc_name);
> +	),
> +
> +	TP_printk("rproc_boot: %s: %s", __get_str(rproc_name), __get_str(event))
> +);
> +
> +TRACE_EVENT(rproc_shutdown,
> +
> +	TP_PROTO(const char *event, const char *rproc_name),
> +
> +	TP_ARGS(event, rproc_name),
> +
> +	TP_STRUCT__entry(
> +		__string(event, event)
> +		__string(rproc_name, rproc_name)
> +	),
> +
> +	TP_fast_assign(
> +		__assign_str(event, event);
> +		__assign_str(rproc_name, rproc_name);
> +	),
> +
> +	TP_printk("rproc_shutdown: %s: %s", __get_str(rproc_name), __get_str(event))
> +);
> +
> +TRACE_EVENT(rproc_recovery,
> +
> +	TP_PROTO(const char *event, const char *rproc_name),
> +
> +	TP_ARGS(event, rproc_name),
> +
> +	TP_STRUCT__entry(
> +		__string(event, event)
> +		__string(rproc_name, rproc_name)
> +	),
> +
> +	TP_fast_assign(
> +		__assign_str(event, event);
> +		__assign_str(rproc_name, rproc_name);
> +	),
> +
> +	TP_printk("rproc_recovery: %s: %s", __get_str(rproc_name), __get_str(event))
> +);
> +
> +TRACE_EVENT(rproc_subdevices,
> +
> +	TP_PROTO(const char *event, const char *rproc_name),
> +
> +	TP_ARGS(event, rproc_name),
> +
> +	TP_STRUCT__entry(
> +		__string(event, event)
> +		__string(rproc_name, rproc_name)
> +	),
> +
> +	TP_fast_assign(
> +		__assign_str(event, event);
> +		__assign_str(rproc_name, rproc_name);
> +	),
> +
> +	TP_printk("rproc_subdevices: %s: %s", __get_str(rproc_name), __get_str(event))
> +);
> +#endif
> +#include <trace/define_trace.h>
> +
> -- 
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