(cc Mel)
On Wed, 13 Jul 2022 14:20:09 +0800 Chuyi Zhou <zhouchuyi@xxxxxxxxxxxxx> wrote:
> From: zhouchuyi <zhouchuyi@xxxxxxxxxxxxx>
>
> When we successfully find a pageblock in fast_find_migrateblock(),
> the block will be set skip-flag through set_pageblock_skip(). However,
> when entering isolate_migratepages_block(), the whole pageblock will
> be skipped due to the branch
> 'if (!valid_page && IS_ALIGNED(low_pfn, pageblock_nr_pages))'.
> Eventually we will goto isolate_abort and isolate nothing. That cause
> fast_find_migrateblock useless.
>
> In this Patch, when we find a suitable pageblock in fast_find_
> migrateblock, we do noting but let isolate_migratepages_block
> to set skip flag to the pageblock after scan it. Normally,
> we would isolate some pages from the fast-find block.
>
> I use mmtest/thpscale-madvhugepage test it. Here is the result:
> baseline patch
> Amean fault-both-1 1331.66 ( 0.00%) 1261.04 * 5.30%*
> Amean fault-both-3 1383.95 ( 0.00%) 1191.69 * 13.89%*
> Amean fault-both-5 1568.13 ( 0.00%) 1445.20 * 7.84%*
> Amean fault-both-7 1819.62 ( 0.00%) 1555.13 * 14.54%*
> Amean fault-both-12 1106.96 ( 0.00%) 1149.43 * -3.84%*
> Amean fault-both-18 2196.93 ( 0.00%) 1875.77 * 14.62%*
> Amean fault-both-24 2642.69 ( 0.00%) 2671.21 * -1.08%*
> Amean fault-both-30 2901.89 ( 0.00%) 2857.32 * 1.54%*
> Amean fault-both-32 3747.00 ( 0.00%) 3479.23 * 7.15%*
>
> Fixes: 70b44595eafe9 ("mm, compaction: use free lists to quickly locate a migration source")
>
> Signed-off-by: zhouchuyi <zhouchuyi@xxxxxxxxxxxxx>
> ---
> mm/compaction.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/mm/compaction.c b/mm/compaction.c
> index 962d05d1e187..abc7b0834471 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -1850,7 +1850,6 @@ static unsigned long fast_find_migrateblock(struct compact_control *cc)
> pfn = cc->zone->zone_start_pfn;
> cc->fast_search_fail = 0;
> found_block = true;
> - set_pageblock_skip(freepage);
> break;
> }
> }
> --
> 2.20.1
>
