On Mon, Aug 17, 2020 at 09:05:32AM -0700, Alexander Duyck wrote: > > >On 8/17/2020 2:35 AM, David Hildenbrand wrote: >> On 17.08.20 10:48, Wei Yang wrote: >> > If "page" is the list head, list_for_each_entry_safe() would stop >> > iteration. >> > >> > Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxxxxxxxxxx> >> > --- >> > mm/page_reporting.c | 2 +- >> > 1 file changed, 1 insertion(+), 1 deletion(-) >> > >> > diff --git a/mm/page_reporting.c b/mm/page_reporting.c >> > index 3bbd471cfc81..aaaa3605123d 100644 >> > --- a/mm/page_reporting.c >> > +++ b/mm/page_reporting.c >> > @@ -178,7 +178,7 @@ page_reporting_cycle(struct page_reporting_dev_info *prdev, struct zone *zone, >> > * the new head of the free list before we release the >> > * zone lock. >> > */ >> > - if (&page->lru != list && !list_is_first(&page->lru, list)) >> > + if (!list_is_first(&page->lru, list)) >> > list_rotate_to_front(&page->lru, list); >> > /* release lock before waiting on report processing */ >> > >> >> Is this a fix or a cleanup? If it's a fix, can this be reproduced easily >> and what ere the effects? >> > >This should be a clean-up. Since the &page->lru != list will always be true. > >If I recall at some point the that was a check for &next->lru != list but I >think I pulled out an additional conditional check somewhere so that we just >go through the start of the loop again and iterate over reported pages until >we are guaranteed to have a non-reported page to rotate to the top of the >list with the general idea being that we wanted the allocator to pull >non-reported pages before reported pages. Hi, Alexander, I see you mentioned in the changelog, this change "mm/page_reporting: rotate reported pages to the tail of the list" brings some performance gain. Would you mind sharing more test detail? I would like to have a try at my side. Thanks :-) -- Wei Yang Help you, Help me
