[RFC PATCH v4] GCOV: profile by modules

[RFC PATCH v4] GCOV: profile by modules

[gengcixi]

From: Cixi Geng <cixi.geng1@unisoc.com>

The CONFIG_GCOV_PROFILE_ALL will compile kernel by profiling entire
kernel which will lead to kernel run slower.Use GCOV_PROFILE_PREREQS
to control part of the kernel modules to open gcov.

Only add SERIAL_GCOV for an example.

Signed-off-by: Cixi Geng <cixi.geng1@unisoc.com>
---
 drivers/tty/serial/Kconfig  |  7 +++++++
 drivers/tty/serial/Makefile |  1 +
 kernel/gcov/Kconfig         | 14 ++++++++++++++
 3 files changed, 22 insertions(+)

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index adf9e80e7dc9..6df002370f18 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -1566,3 +1566,10 @@ endmenu
 
 config SERIAL_MCTRL_GPIO
 	tristate
+
+config SERIAL_GCOV
+	bool "Enable profile gcov for serial directory"
+	depends on GCOV_PROFILE_PREREQS
+	help
+	  The SERIAL_GCOV will add Gcov profiling flags when kernel compiles.
+	  Say 'Y' here if you want the gcov data for the serial directory,
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index d056ee6cca33..17272733db95 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -3,6 +3,7 @@
 # Makefile for the kernel serial device drivers.
 #
 
+GCOV_PROFILE := $(CONFIG_SERIAL_GCOV)
 obj-$(CONFIG_SERIAL_CORE) += serial_core.o
 
 obj-$(CONFIG_SERIAL_EARLYCON) += earlycon.o
diff --git a/kernel/gcov/Kconfig b/kernel/gcov/Kconfig
index 3941a9c48f83..ea8b514f5676 100644
--- a/kernel/gcov/Kconfig
+++ b/kernel/gcov/Kconfig
@@ -51,6 +51,20 @@ config GCOV_PROFILE_ALL
 	larger and run slower. Also be sure to exclude files from profiling
 	which are not linked to the kernel image to prevent linker errors.
 
+config GCOV_PROFILE_PREREQS
+	bool "Profile Kernel subsytem"
+	depends on !COMPILE_TEST
+	depends on GCOV_KERNEL
+	depends on !GCOV_PROFILE_ALL
+	help
+	  This options activates profiling for the specified kernel modules.
+
+	  When some modules need Gcov data, enable this config, then configure
+	  with gcov on the corresponding modules,The directories or files of
+	  these modules will be added profiling flags after kernel compile.
+
+	  If unsure, say N.
+
 choice
 	prompt "Specify GCOV format"
 	depends on GCOV_KERNEL
-- 
2.17.1

Re: [RFC PATCH v4] GCOV: profile by modules

[Peter Oberparleiter]

On 25.05.2020 12:00, gengcixi@gmail.com wrote:
> From: Cixi Geng <cixi.geng1@unisoc.com>
> 
> The CONFIG_GCOV_PROFILE_ALL will compile kernel by profiling entire
> kernel which will lead to kernel run slower.Use GCOV_PROFILE_PREREQS
> to control part of the kernel modules to open gcov.

Maybe rephrase the commit message to make the intention more obvious:

Introduce new configuration option GCOV_PROFILE_PREREQS that can be used
to check whether the prerequisites for enabling gcov profiling for
specific files and directories are met.

> 
> Only add SERIAL_GCOV for an example.
> 
> Signed-off-by: Cixi Geng <cixi.geng1@unisoc.com>
> ---
>  drivers/tty/serial/Kconfig  |  7 +++++++
>  drivers/tty/serial/Makefile |  1 +
>  kernel/gcov/Kconfig         | 14 ++++++++++++++
>  3 files changed, 22 insertions(+)
> 
> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
> index adf9e80e7dc9..6df002370f18 100644
> --- a/drivers/tty/serial/Kconfig
> +++ b/drivers/tty/serial/Kconfig
> @@ -1566,3 +1566,10 @@ endmenu
>  
>  config SERIAL_MCTRL_GPIO
>  	tristate
> +
> +config SERIAL_GCOV
> +	bool "Enable profile gcov for serial directory"
> +	depends on GCOV_PROFILE_PREREQS
> +	help
> +	  The SERIAL_GCOV will add Gcov profiling flags when kernel compiles.
> +	  Say 'Y' here if you want the gcov data for the serial directory,
> diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
> index d056ee6cca33..17272733db95 100644
> --- a/drivers/tty/serial/Makefile
> +++ b/drivers/tty/serial/Makefile
> @@ -3,6 +3,7 @@
>  # Makefile for the kernel serial device drivers.
>  #
>  
> +GCOV_PROFILE := $(CONFIG_SERIAL_GCOV)
>  obj-$(CONFIG_SERIAL_CORE) += serial_core.o
>  
>  obj-$(CONFIG_SERIAL_EARLYCON) += earlycon.o
> diff --git a/kernel/gcov/Kconfig b/kernel/gcov/Kconfig
> index 3941a9c48f83..ea8b514f5676 100644
> --- a/kernel/gcov/Kconfig
> +++ b/kernel/gcov/Kconfig
> @@ -51,6 +51,20 @@ config GCOV_PROFILE_ALL
>  	larger and run slower. Also be sure to exclude files from profiling
>  	which are not linked to the kernel image to prevent linker errors.
>  
> +config GCOV_PROFILE_PREREQS
> +	bool "Profile Kernel subsytem"
> +	depends on !COMPILE_TEST
> +	depends on GCOV_KERNEL
> +	depends on !GCOV_PROFILE_ALL
> +	help
> +	  This options activates profiling for the specified kernel modules.
> +
> +	  When some modules need Gcov data, enable this config, then configure
> +	  with gcov on the corresponding modules,The directories or files of
> +	  these modules will be added profiling flags after kernel compile.
> +
> +	  If unsure, say N.

This is not quite what I had in mind. A user still needs to manually
select GCOV_PROFILE, then GCOV_PROFILE_PREREQS, then SERIAL_GCOV.

My though was that you could provide an automatic config option that is
invisible in the configuration dialog, and that is automatically
selected when all prereqs for enabling GCOV in a module directory are met.

Something like the following:

config GCOV_PROFILE_PREREQS
        bool
        default y if GCOV_KERNEL && !COMPILE_TEST
        default n

There's no need to add GCOV_KERNEL_ALL here since that is about a user
choice ("I want all code compiled with profiling") vs. this new symbol
which is about an ability ("all prereqs for enabling profiling in
specific directories are met).


> +
>  choice
>  	prompt "Specify GCOV format"
>  	depends on GCOV_KERNEL
> 


-- 
Peter Oberparleiter
Linux on Z Development - IBM Germany

Re: [RFC PATCH v4] GCOV: profile by modules

[Cixi Geng]

Peter Oberparleiter <oberpar@linux.ibm.com> 于2020年5月28日周四 下午10:47写道：
>
> On 25.05.2020 12:00, gengcixi@gmail.com wrote:
> > From: Cixi Geng <cixi.geng1@unisoc.com>
> >
> > The CONFIG_GCOV_PROFILE_ALL will compile kernel by profiling entire
> > kernel which will lead to kernel run slower.Use GCOV_PROFILE_PREREQS
> > to control part of the kernel modules to open gcov.
>
> Maybe rephrase the commit message to make the intention more obvious:
>
> Introduce new configuration option GCOV_PROFILE_PREREQS that can be used
> to check whether the prerequisites for enabling gcov profiling for
> specific files and directories are met.
>
> >
> > Only add SERIAL_GCOV for an example.
> >
> > Signed-off-by: Cixi Geng <cixi.geng1@unisoc.com>
> > ---
> >  drivers/tty/serial/Kconfig  |  7 +++++++
> >  drivers/tty/serial/Makefile |  1 +
> >  kernel/gcov/Kconfig         | 14 ++++++++++++++
> >  3 files changed, 22 insertions(+)
> >
> > diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
> > index adf9e80e7dc9..6df002370f18 100644
> > --- a/drivers/tty/serial/Kconfig
> > +++ b/drivers/tty/serial/Kconfig
> > @@ -1566,3 +1566,10 @@ endmenu
> >
> >  config SERIAL_MCTRL_GPIO
> >       tristate
> > +
> > +config SERIAL_GCOV
> > +     bool "Enable profile gcov for serial directory"
> > +     depends on GCOV_PROFILE_PREREQS
> > +     help
> > +       The SERIAL_GCOV will add Gcov profiling flags when kernel compiles.
> > +       Say 'Y' here if you want the gcov data for the serial directory,
> > diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
> > index d056ee6cca33..17272733db95 100644
> > --- a/drivers/tty/serial/Makefile
> > +++ b/drivers/tty/serial/Makefile
> > @@ -3,6 +3,7 @@
> >  # Makefile for the kernel serial device drivers.
> >  #
> >
> > +GCOV_PROFILE := $(CONFIG_SERIAL_GCOV)
> >  obj-$(CONFIG_SERIAL_CORE) += serial_core.o
> >
> >  obj-$(CONFIG_SERIAL_EARLYCON) += earlycon.o
> > diff --git a/kernel/gcov/Kconfig b/kernel/gcov/Kconfig
> > index 3941a9c48f83..ea8b514f5676 100644
> > --- a/kernel/gcov/Kconfig
> > +++ b/kernel/gcov/Kconfig
> > @@ -51,6 +51,20 @@ config GCOV_PROFILE_ALL
> >       larger and run slower. Also be sure to exclude files from profiling
> >       which are not linked to the kernel image to prevent linker errors.
> >
> > +config GCOV_PROFILE_PREREQS
> > +     bool "Profile Kernel subsytem"
> > +     depends on !COMPILE_TEST
> > +     depends on GCOV_KERNEL
> > +     depends on !GCOV_PROFILE_ALL
> > +     help
> > +       This options activates profiling for the specified kernel modules.
> > +
> > +       When some modules need Gcov data, enable this config, then configure
> > +       with gcov on the corresponding modules,The directories or files of
> > +       these modules will be added profiling flags after kernel compile.
> > +
> > +       If unsure, say N.
>
> This is not quite what I had in mind. A user still needs to manually
> select GCOV_PROFILE, then GCOV_PROFILE_PREREQS, then SERIAL_GCOV.
>
> My though was that you could provide an automatic config option that is
> invisible in the configuration dialog, and that is automatically
> selected when all prereqs for enabling GCOV in a module directory are met.
>
> Something like the following:
>
> config GCOV_PROFILE_PREREQS
>         bool
>         default y if GCOV_KERNEL && !COMPILE_TEST
>         default n
>
> There's no need to add GCOV_KERNEL_ALL here since that is about a user
> choice ("I want all code compiled with profiling") vs. this new symbol
> which is about an ability ("all prereqs for enabling profiling in
> specific directories are met).
>
As far as I'm concerned, The GCOV_KERNEL_ALL will conflict with
GCOV_PROFILE_PREREQS，since the GCOV_KERNEL_ALL will profing all
code which contain the new config.
>
> > +
> >  choice
> >       prompt "Specify GCOV format"
> >       depends on GCOV_KERNEL
> >
>
>
> --
> Peter Oberparleiter
> Linux on Z Development - IBM Germany