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    [PATCH] kconfig: Fix Kconfig performance bug · 3f04e7dd
    David Gibson authored
    
    
    When doing its recursive dependency check, scripts/kconfig/conf uses the flag
    SYMBOL_CHECK_DONE to avoid rechecking a symbol it has already checked.
    However, that flag is only set at the top level, so if a symbol is first
    encountered as a dependency of another symbol it will be rechecked every time
    it is encountered until it's encountered at the top level.
    
    This patch adjusts the flag setting so that each symbol will only be checked
    once, regardless of whether it is first encountered at the top level, or while
    recursing down from another symbol.  On complex configurations, this vastly
    speeds up scripts/kconfig/conf.  The config in the powerpc merge tree is
    particularly bad: this patch reduces the time for 'scripts/kconfig/conf -o
    arch/powerpc/Kconfig' by a factor of 40 on a G5.  That's even including the
    time to print the config, so the speedup in the actual checking is more likely
    2 or 3 orders of magnitude.
    
    Signed-off-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
    Signed-off-by: default avatarRoman Zippel <zippel@linux-m68k.org>
    Cc: Sam Ravnborg <sam@ravnborg.org>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    3f04e7dd