Commit 3f04e7dd authored by David Gibson's avatar David Gibson Committed by Linus Torvalds

[PATCH] kconfig: Fix Kconfig performance bug

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>
parent cecd1ca0
......@@ -93,7 +93,6 @@ struct symbol {
#define SYMBOL_NEW 0x0800
#define SYMBOL_AUTO 0x1000
#define SYMBOL_CHECKED 0x2000
#define SYMBOL_CHECK_DONE 0x4000
#define SYMBOL_WARNED 0x8000
#define SYMBOL_MAXLENGTH 256
......
......@@ -731,12 +731,12 @@ struct symbol *sym_check_deps(struct symbol *sym)
struct symbol *sym2;
struct property *prop;
if (sym->flags & SYMBOL_CHECK_DONE)
return NULL;
if (sym->flags & SYMBOL_CHECK) {
printf("Warning! Found recursive dependency: %s", sym->name);
return sym;
}
if (sym->flags & SYMBOL_CHECKED)
return NULL;
sym->flags |= (SYMBOL_CHECK | SYMBOL_CHECKED);
sym2 = sym_check_expr_deps(sym->rev_dep.expr);
......@@ -756,8 +756,13 @@ struct symbol *sym_check_deps(struct symbol *sym)
goto out;
}
out:
if (sym2)
if (sym2) {
printf(" %s", sym->name);
if (sym2 == sym) {
printf("\n");
sym2 = NULL;
}
}
sym->flags &= ~SYMBOL_CHECK;
return sym2;
}
......
......@@ -1933,10 +1933,7 @@ void conf_parse(const char *name)
exit(1);
menu_finalize(&rootmenu);
for_all_symbols(i, sym) {
if (!(sym->flags & SYMBOL_CHECKED) && sym_check_deps(sym))
printf("\n");
else
sym->flags |= SYMBOL_CHECK_DONE;
sym_check_deps(sym);
}
sym_change_count = 1;
......
......@@ -495,10 +495,7 @@ void conf_parse(const char *name)
exit(1);
menu_finalize(&rootmenu);
for_all_symbols(i, sym) {
if (!(sym->flags & SYMBOL_CHECKED) && sym_check_deps(sym))
printf("\n");
else
sym->flags |= SYMBOL_CHECK_DONE;
sym_check_deps(sym);
}
sym_change_count = 1;
......
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