Re: [PATCH 07/14] mm, compaction: Always finish scanning of a full pageblock

From: Vlastimil Babka
Date: Tue Dec 18 2018 - 04:23:59 EST

On 12/15/18 12:03 AM, Mel Gorman wrote:
> When compaction is finishing, it uses a flag to ensure the pageblock is
> complete. However, in general it makes sense to always complete migration
> of a pageblock. Minimally, skip information is based on a pageblock and
> partially scanned pageblocks may incur more scanning in the future. The
> pageblock skip handling also becomes more strict later in the series and
> the hint is more useful if a complete pageblock was always scanned.
> The impact here is potentially on latencies as more scanning is done
> but it's not a consistent win or loss as the scanning is not always a
> high percentage of the pageblock and sometimes it is offset by future
> reductions in scanning. Hence, the results are not presented this time as
> it's a mix of gains/losses without any clear pattern. However, completing
> scanning of the pageblock is important for later patches.
> Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>

Acked-by: Vlastimil Babka <vbabka@xxxxxxx>