Re: page fault scalability patch V12 [0/7]: Overview and performance

Hugh Dickins
2004-12-11T09:23:20Z

On Fri, 10 Dec 2004, Andrew Morton wrote:
> Hugh Dickins <hugh@veritas.com> wrote:
> >
> > My inclination would be simply to remove the mark_page_accessed
> > from do_anonymous_page; but I have no numbers to back that hunch.
>
> With the current implementation of page_referenced() the
> software-referenced bit doesn't matter anyway, as long as the pte's
> referenced bit got set. So as long as the thing is on the active list, we
> can simply remove the mark_page_accessed() call.

Yes, you're right. So we don't need numbers, can just delete that line.

> Except one day the VM might get smarter about pages which are both
> software-referenced and pte-referenced.

And on that day, we'd be making other changes, which might well
involve restoring the mark_page_accessed to do_anonymous_page
and adding it in the similar places which currently lack it.

But for now...

--- 2.6.10-rc3/mm/memory.c 2004-12-05 12:56:12.000000000 +0000
+++ linux/mm/memory.c 2004-12-11 09:18:39.000000000 +0000
@@ -1464,7 +1464,6 @@ do_anonymous_page(struct mm_struct *mm,
vma->vm_page_prot)),
vma);
lru_cache_add_active(page);
- mark_page_accessed(page);
page_add_anon_rmap(page, vma, addr);
}