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Date: Mon, 12 May 2014 13:28:15 -0700 (PDT)
From: David Rientjes <rientjes@google.com>
Subject: Re: [PATCH] mm, compaction: properly signal and act upon lock and
 need_sched() contention
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To: Vlastimil Babka <vbabka@suse.cz>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>, Andrew Morton <akpm@linux-foundation.org>, Hugh Dickins <hughd@google.com>, Greg Thelen <gthelen@google.com>, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Minchan Kim <minchan@kernel.org>, Mel Gorman <mgorman@suse.de>, Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>, Michal Nazarewicz <mina86@mina86.com>, Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>, Christoph Lameter <cl@linux.com>, Rik van Riel <riel@redhat.com>

On Mon, 12 May 2014, Vlastimil Babka wrote:

> diff --git a/mm/compaction.c b/mm/compaction.c
> index 83ca6f9..b34ab7c 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -222,6 +222,27 @@ static bool compact_checklock_irqsave(spinlock_t *lock, unsigned long *flags,
>  	return true;
>  }
>  
> +/*
> + * Similar to compact_checklock_irqsave() (see its comment) for places where
> + * a zone lock is not concerned.
> + *
> + * Returns false when compaction should abort.
> + */

I think we should have some sufficient commentary in the code that 
describes why we do this.

> +static inline bool compact_check_resched(struct compact_control *cc)
> +{

I'm not sure that compact_check_resched() is the appropriate name.  Sure, 
it specifies what the current implementation is, but what it's really 
actually doing is determining when compaction should abort prematurely.

Something like compact_should_abort()?

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