On Wed, Jun 30, 2021 at 02:20:38PM +0200, Michal Hocko wrote:
> On Wed 30-06-21 12:22:48, Matthew Wilcox wrote:
> > We need to decide what 'NR_ANON_THPS' means in a folio-based world where
> > we have folios of all orders. Does it count only the number of pages
> > in folios >= HPAGE_PMD_SIZE? Or does it count the number of pages in
> > folios > PAGE_SIZE?
>
> At this stage we only have PMD based, right? I believe it would be
> simpler to stick with that at the moment and change that to a more
> generic way along with other places which need updating.
>
> Wrt. counters they do count pages so in this case this shouldn't be a
> problem. But we do have counters for pmd mappings and that might need
> some care.
Looking at how these are reported:
show_val_kb(m, "AnonHugePages: ",
global_node_page_state(NR_ANON_THPS));
show_val_kb(m, "ShmemHugePages: ",
global_node_page_state(NR_SHMEM_THPS));
show_val_kb(m, "ShmemPmdMapped: ",
global_node_page_state(NR_SHMEM_PMDMAPPED));
show_val_kb(m, "FileHugePages: ",
global_node_page_state(NR_FILE_THPS));
show_val_kb(m, "FilePmdMapped: ",
global_node_page_state(NR_FILE_PMDMAPPED));
it specifically refers to 'HugePages', so I think we need to only
count folios with order >= PMD_ORDER. I'll make that change to
folio_transhuge() and use folio_transhuge() here.
