Re: [PATCH v10 14/19] rv: Add rtapp container monitor

[Steven Rostedt <rostedt@goodmis.org>]

On Tue, 10 Jun 2025 11:43:39 +0200
Nam Cao <namcao@linutronix.de> wrote:

> Add the container "rtapp" which is the monitor collection for detecting
> problems with real-time applications. The monitors will be added in the
> follow-up commits.
> 
> Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
> Signed-off-by: Nam Cao <namcao@linutronix.de>
> ---
>  kernel/trace/rv/Kconfig                |  1 +
>  kernel/trace/rv/Makefile               |  1 +
>  kernel/trace/rv/monitors/rtapp/Kconfig | 14 +++++++++++
>  kernel/trace/rv/monitors/rtapp/rtapp.c | 33 ++++++++++++++++++++++++++
>  kernel/trace/rv/monitors/rtapp/rtapp.h |  3 +++
>  5 files changed, 52 insertions(+)
>  create mode 100644 kernel/trace/rv/monitors/rtapp/Kconfig
>  create mode 100644 kernel/trace/rv/monitors/rtapp/rtapp.c
>  create mode 100644 kernel/trace/rv/monitors/rtapp/rtapp.h
> 
> diff --git a/kernel/trace/rv/Kconfig b/kernel/trace/rv/Kconfig
> index 6e157f9649915..5c407d2916614 100644
> --- a/kernel/trace/rv/Kconfig
> +++ b/kernel/trace/rv/Kconfig
> @@ -41,6 +41,7 @@ source "kernel/trace/rv/monitors/snroc/Kconfig"
>  source "kernel/trace/rv/monitors/scpd/Kconfig"
>  source "kernel/trace/rv/monitors/snep/Kconfig"
>  source "kernel/trace/rv/monitors/sncid/Kconfig"
> +source "kernel/trace/rv/monitors/rtapp/Kconfig"
>  # Add new monitors here
>  
>  config RV_REACTORS
> diff --git a/kernel/trace/rv/Makefile b/kernel/trace/rv/Makefile
> index f9b2cd0483c3c..9b28c24199955 100644
> --- a/kernel/trace/rv/Makefile
> +++ b/kernel/trace/rv/Makefile
> @@ -12,6 +12,7 @@ obj-$(CONFIG_RV_MON_SNROC) += monitors/snroc/snroc.o
>  obj-$(CONFIG_RV_MON_SCPD) += monitors/scpd/scpd.o
>  obj-$(CONFIG_RV_MON_SNEP) += monitors/snep/snep.o
>  obj-$(CONFIG_RV_MON_SNCID) += monitors/sncid/sncid.o
> +obj-$(CONFIG_RV_MON_RTAPP) += monitors/rtapp/rtapp.o
>  # Add new monitors here
>  obj-$(CONFIG_RV_REACTORS) += rv_reactors.o
>  obj-$(CONFIG_RV_REACT_PRINTK) += reactor_printk.o
> diff --git a/kernel/trace/rv/monitors/rtapp/Kconfig b/kernel/trace/rv/monitors/rtapp/Kconfig
> new file mode 100644
> index 0000000000000..658bb78e733a0
> --- /dev/null
> +++ b/kernel/trace/rv/monitors/rtapp/Kconfig
> @@ -0,0 +1,14 @@
> +config RV_MON_RTAPP
> +	depends on RV
> +	bool "rtapp monitor"
> +	help
> +	  Collection of monitors to check for common problems with real-time
> +	  application that may cause unexpected latency.
> +
> +	  If you are developing a real-time system and not entirely sure whether
> +	  the applications are designed correctly for real-time, you want to say
> +	  Y here.
> +
> +	  Beware that enabling this may have impact on performance, even if the
> +	  monitors are not running. Therefore you probably should say N for
> +	  production kernel.

I'm trying to figure out from the patch how exactly does this cause
performance issues?

Can you elaborate?

Thanks,

-- Steve


> diff --git a/kernel/trace/rv/monitors/rtapp/rtapp.c b/kernel/trace/rv/monitors/rtapp/rtapp.c
> new file mode 100644
> index 0000000000000..fd75fc927d654
> --- /dev/null
> +++ b/kernel/trace/rv/monitors/rtapp/rtapp.c
> @@ -0,0 +1,33 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/rv.h>
> +
> +#define MODULE_NAME "rtapp"
> +
> +#include "rtapp.h"
> +
> +struct rv_monitor rv_rtapp;
> +
> +struct rv_monitor rv_rtapp = {
> +	.name = "rtapp",
> +	.description = "Collection of monitors for detecting problems with real-time applications",
> +};
> +
> +static int __init register_rtapp(void)
> +{
> +	return rv_register_monitor(&rv_rtapp, NULL);
> +}
> +
> +static void __exit unregister_rtapp(void)
> +{
> +	rv_unregister_monitor(&rv_rtapp);
> +}
> +
> +module_init(register_rtapp);
> +module_exit(unregister_rtapp);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Nam Cao <namcao@linutronix.de>");
> +MODULE_DESCRIPTION("Collection of monitors for detecting problems with real-time applications");
> diff --git a/kernel/trace/rv/monitors/rtapp/rtapp.h b/kernel/trace/rv/monitors/rtapp/rtapp.h
> new file mode 100644
> index 0000000000000..4c200d67c7f67
> --- /dev/null
> +++ b/kernel/trace/rv/monitors/rtapp/rtapp.h
> @@ -0,0 +1,3 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +extern struct rv_monitor rv_rtapp;