On Sat 22-10-16 01:46:29, Kirill A. Shutemov wrote: > On Fri, Oct 21, 2016 at 09:51:03PM +0300, Kirill A. Shutemov wrote: > > + case SHEME_HUGE_ALWAYS: > > Oops. Forgot to commit the fixup :-/ > > >From 79b0a3bf4503225d0e6ba553b8496f0c4d55514e Mon Sep 17 00:00:00 2001 > From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> > Date: Mon, 17 Oct 2016 14:44:47 +0300 > Subject: [PATCHv4] shmem: avoid huge pages for small files > > Huge pages are detrimental for small file: they causes noticible > overhead on both allocation performance and memory footprint. > > This patch aimed to address this issue by avoiding huge pages until file > grown to size of huge page. This would cover most of the cases where huge > pages causes regressions in performance. > > Couple notes: > > - if shmem_enabled is set to 'force', the limit is ignored. We still > want to generate as many pages as possible for functional testing. > > - the limit doesn't affect khugepaged behaviour: it still can collapse > pages based on its settings; > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> > --- > Documentation/vm/transhuge.txt | 3 +++ > mm/shmem.c | 5 +++++ > 2 files changed, 8 insertions(+) > > diff --git a/Documentation/vm/transhuge.txt b/Documentation/vm/transhuge.txt > index 2ec6adb5a4ce..d1889c7c8c46 100644 > --- a/Documentation/vm/transhuge.txt > +++ b/Documentation/vm/transhuge.txt > @@ -238,6 +238,9 @@ values: > - "force": > Force the huge option on for all - very useful for testing; > > +To avoid overhead for small files, we don't allocate huge pages for a file > +until it grows to size of huge pages. > + > == Need of application restart == > > The transparent_hugepage/enabled values and tmpfs mount option only affect > diff --git a/mm/shmem.c b/mm/shmem.c > index ad7813d73ea7..49618d2d6330 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -1692,6 +1692,11 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, > goto alloc_huge; > /* TODO: implement fadvise() hints */ > goto alloc_nohuge; > + case SHMEM_HUGE_ALWAYS: > + i_size = i_size_read(inode); > + if (index < HPAGE_PMD_NR && i_size < HPAGE_PMD_SIZE) > + goto alloc_nohuge; > + break; > } > > alloc_huge: > -- > Kirill A. Shutemov -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>