Messages in this thread | | | Date | Fri, 6 Jun 2008 18:04:51 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH -mm 09/25] fix pagecache reclaim referenced bit check |
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On Fri, 06 Jun 2008 16:28:47 -0400 Rik van Riel <riel@redhat.com> wrote:
> From: Rik van Riel <riel@redhat.com> > > The -mm tree contains the patch > vmscan-give-referenced-active-and-unmapped-pages-a-second-trip-around-the-lru.patch > which gives referenced pagecache pages another trip around > the active list. This seems to help keep frequently accessed > pagecache pages in memory. > > However, it means that pagecache pages that get moved to the > inactive list do not have their referenced bit set, and a > reference to the page will not get it moved back to the active > list
Should that be "the next reference"? Because two references _will_ cause the page to be activated?
>. This patch sets the referenced bit on pagecache pages > that get deactivated, so the next access to the page will promote > it back to the active list. > > --- > mm/vmscan.c | 4 ++++ > 1 file changed, 4 insertions(+) > > Index: linux-2.6.26-rc2-mm1/mm/vmscan.c > =================================================================== > --- linux-2.6.26-rc2-mm1.orig/mm/vmscan.c 2008-05-28 12:11:51.000000000 -0400 > +++ linux-2.6.26-rc2-mm1/mm/vmscan.c 2008-05-28 12:14:34.000000000 -0400 > @@ -1062,8 +1062,13 @@ static void shrink_active_list(unsigned > list_add(&page->lru, &l_inactive); > pgmoved++; > } > - } else > + } else { > list_add(&page->lru, &l_inactive); > + if (file && !page_mapped(page)) > + /* Bypass use-once, make the next access count. > + * See mark_page_accessed. */ > + SetPageReferenced(page); > + } > }
Will this change also cause these pages to get a second trip around the inactive list? Or do we at the end of the patch series end up reclaiming pagecache regardless of their PageReferenced()? If so, it seems that we're making the pagecache pages a _lot_ stickier with this change and my one - an additional trip around the active list and an additional one around the inactive list.
Changelog should spell all this out, I guess.
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