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

Vlastimil Babka
2018-12-18T09:23:59Z

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@techsingularity.net>

Acked-by: Vlastimil Babka <vbabka@suse.cz>