On Tue, Jul 6, 2010 at 2:11 PM, <naren.mehra@xxxxxxxxx> wrote:
> Hi,
>
> I am trying to understand the sparsemem implementation in linux for
> NUMA/multiple node systems.
>
> From the available documentation and the sparsemem patches, I am able
> to make out that sparsemem divides memory into different sections and
> if the whole section contains a hole then its marked as invalid
> section and if some pages in a section form a hole then those pages
> are marked reserved. My issue is that this classification, I am not
> able to map it to the code.
>
> e.g. from arch specific code, we call memory_present() to prepare a
> list of sections in a particular node. but unable to find where
> exactly some sections are marked invalid because they contain a hole.
On ARM's sparsememory,
static void arm_memory_present(struct meminfo *mi)
{
int i;
for_each_bank(i, mi) {
struct membank *bank = &mi->bank[i];
memory_present(0, bank_pfn_start(bank), bank_pfn_end(bank));
}
}
It just mark _bank_ which has memory with SECTION_MARKED_PRESENT.
Otherwise, Hole.
>
> Can somebody tell me where in the code are we identifying sections as
> invalid and where we are marking pages as reserved.
Do you mean memmap_init_zone?
--
Kind regards,
Minchan Kim
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