Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> 于2022年8月12日周五 07:07写道： > > On Tue, 2 Aug 2022 01:31:55 +0800 Kairui Song <ryncsn@xxxxxxxxx> wrote: > > > From: Kairui Song <kasong@xxxxxxxxxxx> > > > > folio_entire_mapcount will call PageHeadHuge which is a function call, > > and blocks the compiler from recognizing this redundant load. > > Did you mean folio_test_hugetlb() rather than folio_entire_mapcount()? Thanks for checking out this patch, and Yes, it's folio_test_hugetlb, my mistake... > > > > After rearranging the code, stack usage is dropped from 32 to 24, and > > the function size is smaller (tested on GCC 12): > > > > Before: > > Stack usage: > > mm/util.c:845:5:folio_mapcount 32 static > > Size: > > 0000000000000ea0 00000000000000c7 T folio_mapcount > > > > After: > > Stack usage: > > mm/util.c:845:5:folio_mapcount 24 static > > Size: > > 0000000000000ea0 00000000000000b0 T folio_mapcount > > > > ... > > > > @@ -850,10 +850,10 @@ int folio_mapcount(struct folio *folio) > > return atomic_read(&folio->_mapcount) + 1; > > > > compound = folio_entire_mapcount(folio); > > - nr = folio_nr_pages(folio); > > if (folio_test_hugetlb(folio)) > > return compound; > > ret = compound; > > + nr = folio_nr_pages(folio); > > for (i = 0; i < nr; i++) > > ret += atomic_read(&folio_page(folio, i)->_mapcount) + 1; > > /* File pages has compound_mapcount included in _mapcount */ > > -- > > 2.35.2 Is the rest of the patch a valid fix? Should I send V2?
