On Thu, Dec 03, 2015 at 11:59:48AM +0100, Michal Hocko wrote:
> On Thu 03-12-15 10:08:11, Pradeep Goswami (Pradeep Kumar Goswami) wrote:
> > This patch corrects the number of pages which are rotated on active list.
> > The counter for rotated pages effects the number of pages
> > to be scanned on active pages list in low memory situations.
>
> Why this should be changed?
>
> This seems to be deliberate:
> /*
> * Count referenced pages from currently used mappings as rotated,
> * even though only some of them are actually re-activated. This
> * helps balance scan pressure between file and anonymous pages in
> * get_scan_count.
> */
> reclaim_stat->recent_rotated[file] += nr_rotated;
>
> What kind of problem are you trying to fix?
Actually the numeber of pages which are actually rotated are wrongly
updated, So I thought this might be minor coding error but as pointed
out above, this seems to be deliberate. Thanks for clarifying.
>
> >
> > Signed-off-by: Pradeep Goswami <pradeep.goswami@xxxxxxxxxxxxx>
> > Cc: Rebecca Schultz Zavin <rebecca@xxxxxxxxxxx>
> > Cc: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > ---
> > --- a/mm/vmscan.c 2015-11-18 20:55:38.208838142 +0800
> > +++ b/mm/vmscan.c 2015-11-19 14:37:31.189838998 +0800
> > @@ -1806,7 +1806,6 @@ static void shrink_active_list(unsigned
> >
> > if (page_referenced(page, 0, sc->target_mem_cgroup,
> > &vm_flags)) {
> > - nr_rotated += hpage_nr_pages(page);
> > /*
> > * Identify referenced, file-backed active pages and
> > * give them one more trip around the active list. So
> > @@ -1818,6 +1817,7 @@ static void shrink_active_list(unsigned
> > */
> > if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) {
> > list_add(&page->lru, &l_active);
> > + nr_rotated += hpage_nr_pages(page);
> > continue;
> > }
> > }
> >
> > Thanks,
> > Pradeep.
> > --
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>
> --
> Michal Hocko
> SUSE Labs
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