[U-Boot] [PATCH v5 4/7] dlmalloc: do memset in malloc init as new default config

[Lukasz Majewski]

Hi Przemyslaw,

> This commit introduces new config: CONFIG_SYS_MALLOC_CLEAR_ON_INIT.
> 
> This config is an expert option and is enabled by default.
> 
> The all amount of memory reserved for the malloc, is by default set
> to zero in mem_malloc_init(). When the malloc reserved memory exceeds
> few MiB, then the boot process can slow down.
> 
> So disabling this config, is an expert option to reduce the boot time,
> and can be disabled by Kconfig.
> 
> Note:
> After disable this option, only calloc() will return the pointer
> to the zeroed memory area. Previously, without this option,
> the memory pointed to untouched malloc memory region, was filled
> with zeros. So it means, that code with malloc() calls should
> be reexamined.
> 
> Signed-off-by: Przemyslaw Marczak <p.marczak at samsung.com>
> Reviewed-by: Simon Glass <sjg at chromium.org>
> 
> ---
> Changes v3:
> - squash the commit with the Kconfig option
> 
> Changes v4:
> - adjust commit message for the new config
> 
> Changes v5:
> - change config name to CONFIG_SYS_MALLOC_CLEAR_ON_INIT
> ---
>  Kconfig           | 32 +++++++++++++++++++++++++-------
>  common/dlmalloc.c | 10 +++++++---
>  2 files changed, 32 insertions(+), 10 deletions(-)
> 
> diff --git a/Kconfig b/Kconfig
> index 75bab7f..d6c75d5 100644
> --- a/Kconfig
> +++ b/Kconfig
> @@ -76,13 +76,31 @@ config SYS_MALLOC_F_LEN
>  	  initial serial device and any others that are needed.
>  
>  menuconfig EXPERT
> -        bool "Configure standard U-Boot features (expert users)"
> -        help
> -          This option allows certain base U-Boot options and settings
> -          to be disabled or tweaked. This is for specialized
> -          environments which can tolerate a "non-standard" U-Boot.
> -          Only use this if you really know what you are doing.
> -
> +	bool "Configure standard U-Boot features (expert users)"
> +	default y
> +	help
> +	  This option allows certain base U-Boot options and settings
> +	  to be disabled or tweaked. This is for specialized
> +	  environments which can tolerate a "non-standard" U-Boot.
> +	  Only use this if you really know what you are doing.
> +
> +if EXPERT
> +	config SYS_MALLOC_CLEAR_ON_INIT
> +	bool "Init with zeros the memory reserved for malloc (slow)"
> +	default y
> +	help
> +	  This setting is enabled by default. The reserved malloc
> +	  memory is initialized with zeros, so first malloc calls
> +	  will return the pointer to the zeroed memory. But this
> +	  slows the boot time.
> +
> +	  It is recommended to disable it, when CONFIG_SYS_MALLOC_LEN
> +	  value, has more than few MiB, e.g. when uses bzip2 or bmp
> logo.
> +	  Then the boot time can be significantly reduced.
> +	  Warning:
> +	  When disabling this, please check if malloc calls, maybe
> +	  should be replaced by calloc - if expects zeroed memory.
> +endif
>  endmenu		# General setup
>  
>  menu "Boot images"
> diff --git a/common/dlmalloc.c b/common/dlmalloc.c
> index 6453ee9..b2ce063 100644
> --- a/common/dlmalloc.c
> +++ b/common/dlmalloc.c
> @@ -1535,9 +1535,9 @@ void mem_malloc_init(ulong start, ulong size)
>  
>  	debug("using memory %#lx-%#lx for malloc()\n",
> mem_malloc_start, mem_malloc_end);
> -
> -	memset((void *)mem_malloc_start, 0, size);
> -
> +#ifdef CONFIG_SYS_MALLOC_CLEAR_ON_INIT
> +	memset((void *)mem_malloc_start, 0x0, size);
> +#endif
>  	malloc_bin_reloc();
>  }
>  
> @@ -2948,10 +2948,12 @@ Void_t* cALLOc(n, elem_size) size_t n; size_t
> elem_size; 
>  
>    /* check if expand_top called, in which case don't need to clear */
> +#ifdef CONFIG_SYS_MALLOC_CLEAR_ON_INIT
>  #if MORECORE_CLEARS
>    mchunkptr oldtop = top;
>    INTERNAL_SIZE_T oldtopsize = chunksize(top);
>  #endif
> +#endif
>    Void_t* mem = mALLOc (sz);
>  
>    if ((long)n < 0) return NULL;
> @@ -2977,6 +2979,7 @@ Void_t* cALLOc(n, elem_size) size_t n; size_t
> elem_size; 
>      csz = chunksize(p);
>  
> +#ifdef CONFIG_SYS_MALLOC_CLEAR_ON_INIT
>  #if MORECORE_CLEARS
>      if (p == oldtop && csz > oldtopsize)
>      {
> @@ -2984,6 +2987,7 @@ Void_t* cALLOc(n, elem_size) size_t n; size_t
> elem_size; csz = oldtopsize;
>      }
>  #endif
> +#endif
>  
>      MALLOC_ZERO(mem, csz - SIZE_SZ);
>      return mem;

Acked-by: Lukasz Majewski <l.majewski at samsung.com>

-- 
Best regards,

Lukasz Majewski

Samsung R&D Institute Poland (SRPOL) | Linux Platform Group