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SubjectRe: [PATCH v2] mm: exclude isolated non-lru pages from NR_ISOLATED_ANON or NR_ISOLATED_FILE.
On Fri 14-10-16 23:44:48, Minchan Kim wrote:
> On Fri, Oct 14, 2016 at 03:53:34PM +0200, Michal Hocko wrote:
> > On Fri 14-10-16 22:46:04, Minchan Kim wrote:
> > [...]
> > > > > > Why don't you simply mimic what shrink_inactive_list does? Aka count the
> > > > > > number of isolated pages and then account them when appropriate?
> > > > > >
> > > > > I think i am correcting clearly wrong part. So, there is no need to
> > > > > describe it too detailed. It's a misunderstanding, and i will add
> > > > > more comments as you suggest.
> > > >
> > > > OK, so could you explain why you prefer to relyon __PageMovable rather
> > > > than do a trivial counting during the isolation?
> > >
> > > I don't get it. Could you elaborate it a bit more?
> >
> > It is really simple. You can count the number of file and anonymous
> > pages while they are isolated and then account them to NR_ISOLATED_*
> > later. Basically the same thing we do during the reclaim. We absolutely
> > do not have to rely on __PageMovable and make this code more complex
> > than necessary.
>
> I don't understand your point.
> isolate_migratepages_block can isolate any movable pages, for instance,
> anon, file and non-lru and they are isolated into cc->migratepges.
> Then, acct_isolated accounts them to NR_ISOLATED_*.
> Isn't it same with the one you suggested?
> The problem is we should identify which pages is non-lru movable first.
> If it's not non-lru, it means the page is either anon or file so we
> can account them.
> That's exactly waht Ming Ling did.
>
> Sorry if I didn't get your point. Maybe, it would be better to give
> pseudo code out of your mind for better understanding rather than
> several ping-ping with vague words.

diff --git a/mm/compaction.c b/mm/compaction.c
index 0409a4ad6ea1..6584705a46f6 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -685,7 +685,8 @@ static bool too_many_isolated(struct zone *zone)
*/
static unsigned long
isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
- unsigned long end_pfn, isolate_mode_t isolate_mode)
+ unsigned long end_pfn, isolate_mode_t isolate_mode,
+ unsigned long *isolated_file, unsigned long *isolated_anon)
{
struct zone *zone = cc->zone;
unsigned long nr_scanned = 0, nr_isolated = 0;
@@ -866,6 +867,10 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,

/* Successfully isolated */
del_page_from_lru_list(page, lruvec, page_lru(page));
+ if (page_is_file_cache(page))
+ (*isolated_file)++;
+ else
+ (*isolated_anon)++;

isolate_success:
list_add(&page->lru, &cc->migratepages);
Makes more sense?
--
Michal Hocko
SUSE Labs

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