linux-kernel - Re: [PATCH 0/3] OOM detection rework v4

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Date:	Fri, 26 Feb 2016 18:27:16 +0800
From:	"Hillf Danton" <hillf.zj@...baba-inc.com>
To:	"'Michal Hocko'" <mhocko@...nel.org>
Cc:	"'Hugh Dickins'" <hughd@...gle.com>,
	"'Andrew Morton'" <akpm@...ux-foundation.org>,
	"'Linus Torvalds'" <torvalds@...ux-foundation.org>,
	"'Johannes Weiner'" <hannes@...xchg.org>,
	"'Mel Gorman'" <mgorman@...e.de>,
	"'David Rientjes'" <rientjes@...gle.com>,
	"'Tetsuo Handa'" <penguin-kernel@...ove.sakura.ne.jp>,
	"'KAMEZAWA Hiroyuki'" <kamezawa.hiroyu@...fujitsu.com>,
	<linux-mm@...ck.org>, "'LKML'" <linux-kernel@...r.kernel.org>,
	"'Sergey Senozhatsky'" <sergey.senozhatsky.work@...il.com>
Subject: Re: [PATCH 0/3] OOM detection rework v4

>> 
> > --- a/mm/page_alloc.c	Thu Feb 25 15:43:18 2016
> > +++ b/mm/page_alloc.c	Fri Feb 26 15:18:55 2016
> > @@ -3113,6 +3113,8 @@ should_reclaim_retry(gfp_t gfp_mask, uns
> >  	struct zone *zone;
> >  	struct zoneref *z;
> >
> > +	if (order <= PAGE_ALLOC_COSTLY_ORDER)
> > +		return true;
> 
> This is defeating the whole purpose of the rework - to behave
> deterministically. You have just disabled the oom killer completely.
> This is not the way to go
> 
Then in another direction, below is what I can do.

thanks
Hillf
--- a/mm/page_alloc.c	Thu Feb 25 15:43:18 2016
+++ b/mm/page_alloc.c	Fri Feb 26 18:14:59 2016
@@ -3366,8 +3366,11 @@ retry:
 		no_progress_loops++;
 
 	if (should_reclaim_retry(gfp_mask, order, ac, alloc_flags,
-				 did_some_progress > 0, no_progress_loops))
+				 did_some_progress > 0, no_progress_loops)) {
+		/* Burn more cycles if any zone seems to satisfy our request */
+		no_progress_loops /= 2;
 		goto retry;
+	}
 
 	/* Reclaim has failed us, start killing things */
 	page = __alloc_pages_may_oom(gfp_mask, order, ac, &did_some_progress);
--