On Wed, Jul 4, 2012 at 2:20 AM, Mel Gorman [off-list ref] wrote:

On Wed, Jul 04, 2012 at 09:40:30AM +0800, Jiang Liu wrote:

quoted

quoted

It's a bit ugly calling set_pageblock_order() from both sparse_init()
and from free_area_init_core().  Can we find a single place from which
to call it?  It looks like here:

--- a/init/main.c~a
+++ a/init/main.c

@@ -514,6 +514,7 @@ asmlinkage void __init start_kernel(void
               __stop___param - __start___param,
               -1, -1, &unknown_bootoption);

+   set_pageblock_order();
    jump_label_init();

    /*

would do the trick?

(free_area_init_core is __paging_init and set_pageblock_order() is
__init.  I'm too lazy to work out if that's wrong)

Hi Andrew,
      Thanks for you comments. Yes, this's an issue.
And we are trying to find a way to setup  pageorder_block as
early as possible. Yinghai has suggested a good way for IA64,
but we still need help from PPC experts because PPC has the
same issue and I'm not familiar with PPC architecture.
We will submit another patch once we find an acceptable
solution here.

I think it's overkill to try and do this on a per-architecture basis unless
you are aware of a case where the per-architecture code cares about the
value of pageblock_order. I find it implausible that the architecture
needs to know the value very early in boot as pageblock_order is part of
the arch-independent memory model. Andrew's suggestion seems reasonable
to me once the section mess is figured out.

cma, dma_continugous_reserve is referring pageblock_order very early too.
just after init_memory_mapping() for x86's setup_arch.

so set pageblock_order early looks like my -v2 patch is right way.

current question: need to powerpc guys to check who to set that early.

Thanks

Yinghai

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