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From: Steven Rostedt <rostedt@goodmis.org>
To: changbin.du@intel.com
Cc: yamada.masahiro@socionext.com, michal.lkml@markovi.net,
	tglx@linutronix.de, mingo@redhat.com, akpm@linux-foundation.org,
	rdunlap@infradead.org, x86@kernel.org, lgirdwood@gmail.com,
	broonie@kernel.org, arnd@arndb.de, linux-kbuild@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org
Subject: Re: [PATCH v2 3/5] kernel hacking: new config NO_AUTO_INLINE to disable compiler auto-inline optimizations
Date: Wed, 2 May 2018 10:07:48 -0400	[thread overview]
Message-ID: <20180502100748.3fd41bae@gandalf.local.home> (raw)
In-Reply-To: <1525268700-10631-4-git-send-email-changbin.du@intel.com>

On Wed,  2 May 2018 21:44:58 +0800
changbin.du@intel.com wrote:

> From: Changbin Du <changbin.du@intel.com>
> 
> This patch add a new kernel hacking option NO_AUTO_INLINE. Selecting
> this option will prevent the compiler from optimizing the kernel by
> auto-inlining functions not marked with the inline keyword.
> 
> With this option, only functions explicitly marked with "inline" will
> be inlined. This will allow the function tracer to trace more functions
> because it only traces functions that the compiler has not inlined.
> 
> Signed-off-by: Changbin Du <changbin.du@intel.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>

I'm fine with this patch if others are OK with it too.

Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

-- Steve

> 
> ---
> v2: Some grammar updates from Steven.
> ---
>  Makefile          |  6 ++++++
>  lib/Kconfig.debug | 18 ++++++++++++++++++
>  2 files changed, 24 insertions(+)
> 
> diff --git a/Makefile b/Makefile
> index 619a85a..eb694f6 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -775,6 +775,12 @@ KBUILD_CFLAGS 	+= $(call cc-option, -femit-struct-debug-baseonly) \
>  		   $(call cc-option,-fno-var-tracking)
>  endif
>  
> +ifdef CONFIG_NO_AUTO_INLINE
> +KBUILD_CFLAGS   += $(call cc-option, -fno-inline-functions) \
> +		   $(call cc-option, -fno-inline-small-functions) \
> +		   $(call cc-option, -fno-inline-functions-called-once)
> +endif
> +
>  ifdef CONFIG_FUNCTION_TRACER
>  ifndef CC_FLAGS_FTRACE
>  CC_FLAGS_FTRACE := -pg
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index c40c7b7..ab55801 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -198,6 +198,24 @@ config GDB_SCRIPTS
>  	  instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
>  	  for further details.
>  
> +config NO_AUTO_INLINE
> +	bool "Disable compiler auto-inline optimizations"
> +	default n
> +	help
> +	  This will prevent the compiler from optimizing the kernel by
> +	  auto-inlining functions not marked with the inline keyword.
> +	  With this option, only functions explicitly marked with
> +	  "inline" will be inlined. This will allow the function tracer
> +	  to trace more functions because it only traces functions that
> +	  the compiler has not inlined.
> +
> +	  Enabling this function can help debugging a kernel if using
> +	  the function tracer. But it can also change how the kernel
> +	  works, because inlining functions may change the timing,
> +	  which could make it difficult while debugging race conditions.
> +
> +	  If unsure, select N.
> +
>  config ENABLE_WARN_DEPRECATED
>  	bool "Enable __deprecated logic"
>  	default y

  reply	other threads:[~2018-05-02 14:07 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-02 13:44 [PATCH v2 0/5] kernel hacking: GCC optimization for debug experience (-Og) changbin.du
2018-05-02 13:44 ` [PATCH v2 1/5] x86/mm: surround level4_kernel_pgt with #ifdef CONFIG_X86_5LEVEL...#endif changbin.du
2018-05-02 13:44 ` [PATCH v2 2/5] regulator: add dummy function of_find_regulator_by_node changbin.du
2018-05-02 13:44 ` [PATCH v2 3/5] kernel hacking: new config NO_AUTO_INLINE to disable compiler auto-inline optimizations changbin.du
2018-05-02 14:07   ` Steven Rostedt [this message]
2018-05-02 20:27   ` Arnd Bergmann
2018-05-03 13:00     ` Du, Changbin
2018-05-03 14:16       ` Steven Rostedt
2018-05-02 13:44 ` [PATCH v2 4/5] kernel hacking: new config DEBUG_EXPERIENCE to apply GCC -Og optimization changbin.du
2018-05-02 14:17   ` Steven Rostedt
2018-05-02 20:45     ` Andrew Morton
2018-05-03  1:19       ` Steven Rostedt
2018-05-03 13:45         ` Du, Changbin
2018-05-03 14:28           ` Steven Rostedt
2018-05-05 23:57             ` Du, Changbin
2018-05-06  0:27               ` Randy Dunlap
2018-05-02 19:26   ` Randy Dunlap
2018-05-02 13:45 ` [PATCH v2 5/5] asm-generic: fix build error in fix_to_virt with CONFIG_DEBUG_EXPERIENCE changbin.du
2018-05-02 14:19   ` Steven Rostedt
2018-05-03 13:25     ` Du, Changbin
2018-05-03 14:19       ` Steven Rostedt
2018-05-03 16:39         ` weylin
2018-05-02 14:56 ` [PATCH v2 0/5] kernel hacking: GCC optimization for debug experience (-Og) Daniel Thompson
2018-05-03 13:49   ` Du, Changbin

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