On 2012-7-3 4:43, Yinghai Lu wrote:
> On Sun, Jul 1, 2012 at 7:01 PM, Jiang Liu <[email protected]> wrote:
>> Hi Yinghai,
>> The patch fails compilation as below:
>> mm/page_alloc.c:151: error: initializer element is not constant
>> mm/page_alloc.c:151: error: expected ‘,’ or ‘;’ before ‘__attribute__’
>>
>> On IA64, HUGETLB_PAGE_ORDER has dependency on variable hpage_shift.
>> # define HUGETLB_PAGE_ORDER (HPAGE_SHIFT - PAGE_SHIFT)
>> # define HPAGE_SHIFT hpage_shift
>>
>> And hpage_shift could be changed by early parameter "hugepagesz".
>> So seems will still need to keep function set_pageblock_order().
>
> ah, then use use _DEFAULT instead and later could update that in earlyparam.
>
> So attached -v2 should work.
Hi Yinghai,
I'm afraid the v2 will break powerpc. Currently only IA64 and PowerPC
supports variable hugetlb size.
HPAGE_SHIFT is a variable default to 0 on powerpc. But seems PowerPC
is doing something wrong here, according to it's mm initialization
sequence as below:
start_kernel()
setup_arch()
paging_init()
free_area_init_node()
set_pageblock_order()
refer to HPAGE_SHIFT (still 0)
init_rest()
do_initcalls()
hugetlbpage_init()
setup HPAGE_SHIFT
That means pageblock_order is always set to "MAX_ORDER - 1", not sure
whether this is intended. And it has the same issue as IA64 of wasting
memory if CONFIG_SPARSE is enabled.
So it would be better to keep function set_pageblock_order(), it will
fix the memory wasting on both IA64 and PowerPC.
Thanks!
Gerry
>
> Thanks
>
> Yinghai
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