linux-kernel - Re: [PATCH] Allow compaction of unevictable pages

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Date:	Mon, 9 Mar 2015 13:05:05 -0400
From:	Eric B Munson <emunson@...mai.com>
To:	David Rientjes <rientjes@...gle.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Vlastimil Babka <vbabka@...e.cz>,
	Thomas Gleixner <tglx@...utronix.de>,
	Christoph Lameter <cl@...ux.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Mel Gorman <mgorman@...e.de>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Allow compaction of unevictable pages

On Fri, 06 Mar 2015, David Rientjes wrote:

> On Fri, 6 Mar 2015, Eric B Munson wrote:
> 
> > diff --git a/mm/compaction.c b/mm/compaction.c
> > index 8c0d945..33c81e1 100644
> > --- a/mm/compaction.c
> > +++ b/mm/compaction.c
> > @@ -1056,7 +1056,7 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
> >  {
> >  	unsigned long low_pfn, end_pfn;
> >  	struct page *page;
> > -	const isolate_mode_t isolate_mode =
> > +	const isolate_mode_t isolate_mode = ISOLATE_UNEVICTABLE |
> >  		(cc->mode == MIGRATE_ASYNC ? ISOLATE_ASYNC_MIGRATE : 0);
> >  
> >  	/*
> 
> I agree that memory compaction should be isolating and migrating 
> unevictable memory for better results, and we have been running with a 
> similar patch internally for about a year for the same purpose as you, 
> higher probability of allocating hugepages.
> 
> This would be better off removing the notion of ISOLATE_UNEVICTABLE 
> entirely, however, since CMA and now memory compaction would be using it, 
> so the check in __isolate_lru_page() is no longer necessary.  Has the 
> added bonus of removing about 10 lines of soure code.

Thanks for having a look, I will send out a V2 that removes
ISOLATE_UNEVICTABLE and the check in __isolate_lru_page().

Eric

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