Messages in this thread |  | | | From | "Luck, Tony" <> | | Date | Wed, 2 Sep 2009 16:27:15 -0700 | | Subject | RE: [RFC PATCH] Add TRACE_IRQFLAGS_SUPPORT, LOCKDEP_SUPPORT then enable ftrace for ia64 |
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>> diff -BruN linux-2.6.31-rc6/arch/ia64/include/asm/page.h >> linux-2.6.31-rc6-lockdep/arch/ia64/include/asm/page.h >> --- linux-2.6.31-rc6/arch/ia64/include/asm/page.h 2009-08-13 >> 15:43:34.000000000 -0700 >> +++ linux-2.6.31-rc6-lockdep/arch/ia64/include/asm/page.h 2009-08-23 >> 18:59:00.000000000 -0700 >> @@ -41,7 +41,7 @@ >> #define PAGE_SIZE (__IA64_UL_CONST(1) << PAGE_SHIFT) >> #define PAGE_MASK (~(PAGE_SIZE - 1)) >> >> -#define PERCPU_PAGE_SHIFT 16 /* log2() of max. size of per-CPU area */ >> +#define PERCPU_PAGE_SHIFT 20 /*16 log2() of max. size of per-CPU area */ >> #define PERCPU_PAGE_SIZE (__IA64_UL_CONST(1) << PERCPU_PAGE_SHIFT) > > Why was this seemingly unrelated change done in a lockdep patch?
IIRC it is because the lockdep code needs a lot more percpu memory than the 64K that ia64 allocates.
But I think that I'd prefer to only allocate the extra space when it is needed:
#ifdef CONFIG_LOCKDEP #define PERCPU_PAGE_SHIFT 20 /* Need a Megabyte for lockdep */ #else #define PERCPU_PAGE_SHIFT 16 /* 64K should be enough for normal use */ #endif -Tony
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