Hi Przemyslaw,
On Fri, 20 Feb 2015 12:06:17 +0100
Przemyslaw Marczak <p.marc...@samsung.com> wrote:
> This commit introduces new config: CONFIG_SYS_MALLOC_INIT_SKIP_ZEROING.
>
> Before this change, the all amount of memory reserved for the malloc,
> was set to zero in mem_malloc_init(). When the malloc reserved memory
> exceeds few MiB, then the boot process can slow down.
>
> So enabling this config, is an option to reduce the boot time.
>
> This option can be enabled by Kconfig.
>
> Note:
> After enable this option, only calloc() will return the pointer to 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.marc...@samsung.com>
> Reviewed-by: Simon Glass <s...@chromium.org>
>
> ---
> Changes v3:
> - squash the commit with the Kconfig option
> ---
> Kconfig | 26 +++++++++++++++++++-------
> common/dlmalloc.c | 10 +++++++---
> 2 files changed, 26 insertions(+), 10 deletions(-)
>
> diff --git a/Kconfig b/Kconfig
> index 75bab7f..87d4daf 100644
> --- a/Kconfig
> +++ b/Kconfig
> @@ -76,13 +76,25 @@ 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)"
> + 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_INIT_SKIP_ZEROING
> + bool "Skip memset at malloc init (reduce boot time)"
> + help
> + This avoids zeroing memory reserved for malloc at malloc init.
> + Significant boot time reduction is visible for configs in which
> + CONFIG_SYS_MALLOC_LEN value, has more than few MiB.
> + Useful for bzip2, bmp logo.
> + Warning:
> + When enabling 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..63f68ed 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);
> -
> +#ifndef CONFIG_SYS_MALLOC_INIT_SKIP_ZEROING
> + 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 */
> +#ifndef CONFIG_SYS_MALLOC_INIT_SKIP_ZEROING
> #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);
>
> +#ifndef CONFIG_SYS_MALLOC_INIT_SKIP_ZEROING
> #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;
You are adding only "ifndef" conditionals.
IMHO,
Isn't "#ifdef CONFIG_SYS_MALLOC_INIT_ZEROING" better?
(Generally speaking, CONFIG options that disable a feature are not preferable.)
You also need to add "default y" to the Kconfig
and add "# CONIFG_SYS_MALLOC_INIT_ZEROING is not set" to your defconfig.
Best Regards
Masahiro Yamada
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