linux-kernel - Re: [PATCH] drm: Reduce object size of drm_dev_printk/DRM_DEV

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Message-ID: <87mv5j3reg.fsf@nikula.org>
Date:   Mon, 25 Sep 2017 15:16:07 +0300
From:   Jani Nikula <jani.nikula@...ux.intel.com>
To:     Joe Perches <joe@...ches.com>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Sean Paul <seanpaul@...omium.org>,
        David Airlie <airlied@...ux.ie>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm: Reduce object size of drm_dev_printk/DRM_DEV_<LEVEL> uses

On Mon, 25 Sep 2017, Joe Perches <joe@...ches.com> wrote:
> Remove unnecessary function_name and prefix arguments.
> Removing these arguments reduces object size.
>
> prefix is used to add an "ERROR" prefix to the format for
> DRM_DEV_ERROR and is an empty string for all other uses.
> This string can be added instead by the DRM_DEV_ERROR macro.
>
> function_name is used to emit the calling function.
> This can be done by using %ps and __builtin_return_address(0).

Did you diff the dmesgs to see how much that gets skewed from __func__
by optimizations?

BR,
Jani.


>
> Signed-off-by: Joe Perches <joe@...ches.com>
> ---
>  drivers/gpu/drm/drm_drv.c | 12 +++++-------
>  include/drm/drmP.h        | 42 ++++++++++++++++++------------------------
>  include/drm/drm_drv.h     |  5 ++---
>  3 files changed, 25 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index be38ac7050d4..4d0f2c5197f3 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -74,11 +74,8 @@ static bool drm_core_init_complete = false;
>  
>  static struct dentry *drm_debugfs_root;
>  
> -#define DRM_PRINTK_FMT "[" DRM_NAME ":%s]%s %pV"
> -
>  void drm_dev_printk(const struct device *dev, const char *level,
> -		    unsigned int category, const char *function_name,
> -		    const char *prefix, const char *format, ...)
> +		    unsigned int category, const char *format, ...)
>  {
>  	struct va_format vaf;
>  	va_list args;
> @@ -91,10 +88,11 @@ void drm_dev_printk(const struct device *dev, const char *level,
>  	vaf.va = &args;
>  
>  	if (dev)
> -		dev_printk(level, dev, DRM_PRINTK_FMT, function_name, prefix,
> -			   &vaf);
> +		dev_printk(level, dev, "[" DRM_NAME ":%ps] %pV",
> +			   __builtin_return_address(0), &vaf);
>  	else
> -		printk("%s" DRM_PRINTK_FMT, level, function_name, prefix, &vaf);
> +		printk("%s[" DRM_NAME ":%ps] %pV",
> +		       level, __builtin_return_address(0), &vaf);
>  
>  	va_end(args);
>  }
> diff --git a/include/drm/drmP.h b/include/drm/drmP.h
> index 7277783a4ff0..16dd63ffa1ff 100644
> --- a/include/drm/drmP.h
> +++ b/include/drm/drmP.h
> @@ -172,8 +172,8 @@ struct pci_controller;
>   * \param arg arguments
>   */
>  #define DRM_DEV_ERROR(dev, fmt, ...)					\
> -	drm_dev_printk(dev, KERN_ERR, DRM_UT_NONE, __func__, " *ERROR*",\
> -		       fmt, ##__VA_ARGS__)
> +	drm_dev_printk(dev, KERN_ERR, DRM_UT_NONE,			\
> +		       "*ERROR* " fmt, ##__VA_ARGS__)
>  #define DRM_ERROR(fmt, ...)						\
>  	drm_printk(KERN_ERR, DRM_UT_NONE, fmt,	##__VA_ARGS__)
>  
> @@ -196,8 +196,8 @@ struct pci_controller;
>  	DRM_DEV_ERROR_RATELIMITED(NULL, fmt, ##__VA_ARGS__)
>  
>  #define DRM_DEV_INFO(dev, fmt, ...)					\
> -	drm_dev_printk(dev, KERN_INFO, DRM_UT_NONE, __func__, "", fmt,	\
> -		       ##__VA_ARGS__)
> +	drm_dev_printk(dev, KERN_INFO, DRM_UT_NONE,			\
> +		       fmt, ##__VA_ARGS__)
>  
>  #define DRM_DEV_INFO_ONCE(dev, fmt, ...)				\
>  ({									\
> @@ -214,50 +214,44 @@ struct pci_controller;
>   * \param fmt printf() like format string.
>   * \param arg arguments
>   */
> -#define DRM_DEV_DEBUG(dev, fmt, args...)				\
> -	drm_dev_printk(dev, KERN_DEBUG, DRM_UT_CORE, __func__, "", fmt,	\
> -		       ##args)
> +#define DRM_DEV_DEBUG(dev, fmt, ...)					\
> +	drm_dev_printk(dev, KERN_DEBUG, DRM_UT_CORE, fmt, ##__VA_ARGS__)
>  #define DRM_DEBUG(fmt, ...)						\
>  	drm_printk(KERN_DEBUG, DRM_UT_CORE, fmt, ##__VA_ARGS__)
>  
> -#define DRM_DEV_DEBUG_DRIVER(dev, fmt, args...)				\
> -	drm_dev_printk(dev, KERN_DEBUG, DRM_UT_DRIVER, __func__, "",	\
> -		       fmt, ##args)
> +#define DRM_DEV_DEBUG_DRIVER(dev, fmt, ...)				\
> +	drm_dev_printk(dev, KERN_DEBUG, DRM_UT_DRIVER, fmt, ##__VA_ARGS__)
>  #define DRM_DEBUG_DRIVER(fmt, ...)					\
>  	drm_printk(KERN_DEBUG, DRM_UT_DRIVER, fmt, ##__VA_ARGS__)
>  
> -#define DRM_DEV_DEBUG_KMS(dev, fmt, args...)				\
> -	drm_dev_printk(dev, KERN_DEBUG, DRM_UT_KMS, __func__, "", fmt,	\
> -		       ##args)
> +#define DRM_DEV_DEBUG_KMS(dev, fmt, ...)				\
> +	drm_dev_printk(dev, KERN_DEBUG, DRM_UT_KMS, fmt, ##__VA_ARGS__)
>  #define DRM_DEBUG_KMS(fmt, ...)					\
>  	drm_printk(KERN_DEBUG, DRM_UT_KMS, fmt, ##__VA_ARGS__)
>  
> -#define DRM_DEV_DEBUG_PRIME(dev, fmt, args...)				\
> -	drm_dev_printk(dev, KERN_DEBUG, DRM_UT_PRIME, __func__, "",	\
> -		       fmt, ##args)
> +#define DRM_DEV_DEBUG_PRIME(dev, fmt, ...)				\
> +	drm_dev_printk(dev, KERN_DEBUG, DRM_UT_PRIME, ##__VA_ARGS__)
>  #define DRM_DEBUG_PRIME(fmt, ...)					\
>  	drm_printk(KERN_DEBUG, DRM_UT_PRIME, fmt, ##__VA_ARGS__)
>  
> -#define DRM_DEV_DEBUG_ATOMIC(dev, fmt, args...)				\
> -	drm_dev_printk(dev, KERN_DEBUG, DRM_UT_ATOMIC, __func__, "",	\
> -		       fmt, ##args)
> +#define DRM_DEV_DEBUG_ATOMIC(dev, fmt, ...)				\
> +	drm_dev_printk(dev, KERN_DEBUG, DRM_UT_ATOMIC, fmt, ##__VA_ARGS__)
>  #define DRM_DEBUG_ATOMIC(fmt, ...)					\
>  	drm_printk(KERN_DEBUG, DRM_UT_ATOMIC, fmt, ##__VA_ARGS__)
>  
> -#define DRM_DEV_DEBUG_VBL(dev, fmt, args...)				\
> -	drm_dev_printk(dev, KERN_DEBUG, DRM_UT_VBL, __func__, "", fmt,	\
> -		       ##args)
> +#define DRM_DEV_DEBUG_VBL(dev, fmt, ...)				\
> +	drm_dev_printk(dev, KERN_DEBUG, DRM_UT_VBL, fmt, ##__VA_ARGS__)
>  #define DRM_DEBUG_VBL(fmt, ...)					\
>  	drm_printk(KERN_DEBUG, DRM_UT_VBL, fmt, ##__VA_ARGS__)
>  
> -#define _DRM_DEV_DEFINE_DEBUG_RATELIMITED(dev, level, fmt, args...)	\
> +#define _DRM_DEV_DEFINE_DEBUG_RATELIMITED(dev, level, fmt, ...)		\
>  ({									\
>  	static DEFINE_RATELIMIT_STATE(_rs,				\
>  				      DEFAULT_RATELIMIT_INTERVAL,	\
>  				      DEFAULT_RATELIMIT_BURST);		\
>  	if (__ratelimit(&_rs))						\
>  		drm_dev_printk(dev, KERN_DEBUG, DRM_UT_ ## level,	\
> -			       __func__, "", fmt, ##args);		\
> +			       fmt, ##__VA_ARGS__);		\
>  })
>  
>  /**
> diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
> index 71bbaaec836d..f6430f183ca8 100644
> --- a/include/drm/drm_drv.h
> +++ b/include/drm/drm_drv.h
> @@ -592,10 +592,9 @@ struct drm_driver {
>  	int dev_priv_size;
>  };
>  
> -__printf(6, 7)
> +__printf(4, 5)
>  void drm_dev_printk(const struct device *dev, const char *level,
> -		    unsigned int category, const char *function_name,
> -		    const char *prefix, const char *format, ...);
> +		    unsigned int category, const char *format, ...);
>  __printf(3, 4)
>  void drm_printk(const char *level, unsigned int category,
>  		const char *format, ...);

-- 
Jani Nikula, Intel Open Source Technology Center