From 7efc3b7261030da79001c00d92bc3392fd6c664c Mon Sep 17 00:00:00 2001 From: Chuyi Zhou Date: Wed, 13 Jul 2022 14:20:09 +0800 Subject: [PATCH] mm/compaction: fix set skip in fast_find_migrateblock 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 makes 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%* Link: https://lkml.kernel.org/r/20220713062009.597255-1-zhouchuyi@bytedance.com Fixes: 70b44595eafe9 ("mm, compaction: use free lists to quickly locate a migration source") Signed-off-by: zhouchuyi Cc: Mel Gorman Signed-off-by: Andrew Morton --- mm/compaction.c | 1 - 1 file changed, 1 deletion(-) diff --git a/mm/compaction.c b/mm/compaction.c index e2a9615f5fde..c4e4453187a2 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1851,7 +1851,6 @@ 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; } }