From e6e0c7673012f42c6fb8d89af71cd7607c93e0a5 Mon Sep 17 00:00:00 2001 From: Baolin Wang Date: Fri, 7 Jul 2023 16:51:47 +0800 Subject: mm: compaction: skip the memory hole rapidly when isolating free pages Just like commit 9721fd82351d ("mm: compaction: skip memory hole rapidly when isolating migratable pages"), I can see it will also take more time to skip the larger memory hole (range: 0x1000000000 - 0x1800000000) when isolating free pages on my machine with below memory layout. So like commit 9721fd82351d, adding a new helper to skip the memory hole rapidly, which can reduce the time consumed from about 70us to less than 1us. [ 0.000000] Zone ranges: [ 0.000000] DMA [mem 0x0000000040000000-0x00000000ffffffff] [ 0.000000] DMA32 empty [ 0.000000] Normal [mem 0x0000000100000000-0x0000001fa7ffffff] [ 0.000000] Movable zone start for each node [ 0.000000] Early memory node ranges [ 0.000000] node 0: [mem 0x0000000040000000-0x0000000fffffffff] [ 0.000000] node 0: [mem 0x0000001800000000-0x0000001fa3c7ffff] [ 0.000000] node 0: [mem 0x0000001fa3c80000-0x0000001fa3ffffff] [ 0.000000] node 0: [mem 0x0000001fa4000000-0x0000001fa402ffff] [ 0.000000] node 0: [mem 0x0000001fa4030000-0x0000001fa40effff] [ 0.000000] node 0: [mem 0x0000001fa40f0000-0x0000001fa73cffff] [ 0.000000] node 0: [mem 0x0000001fa73d0000-0x0000001fa745ffff] [ 0.000000] node 0: [mem 0x0000001fa7460000-0x0000001fa746ffff] [ 0.000000] node 0: [mem 0x0000001fa7470000-0x0000001fa758ffff] [ 0.000000] node 0: [mem 0x0000001fa7590000-0x0000001fa7ffffff] [shikemeng@huaweicloud.com: avoid missing last page block in section after skip offline sections] Link: https://lkml.kernel.org/r/20230804110454.2935878-1-shikemeng@huaweicloud.com Link: https://lkml.kernel.org/r/20230804110454.2935878-2-shikemeng@huaweicloud.com Link: https://lkml.kernel.org/r/d2ba7e41ee566309b594311207ffca736375fc16.1688715750.git.baolin.wang@linux.alibaba.com Signed-off-by: Baolin Wang Signed-off-by: Kemeng Shi Reviewed-by: David Hildenbrand Reviewed-by: "Huang, Ying" Cc: Mel Gorman Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- mm/compaction.c | 34 +++++++++++++++++++++++++++++++++- 1 file changed, 33 insertions(+), 1 deletion(-) (limited to 'mm/compaction.c') diff --git a/mm/compaction.c b/mm/compaction.c index 43358efdbdc2..02239abed6ce 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -249,11 +249,36 @@ static unsigned long skip_offline_sections(unsigned long start_pfn) return 0; } + +/* + * If the PFN falls into an offline section, return the end PFN of the + * next online section in reverse. If the PFN falls into an online section + * or if there is no next online section in reverse, return 0. + */ +static unsigned long skip_offline_sections_reverse(unsigned long start_pfn) +{ + unsigned long start_nr = pfn_to_section_nr(start_pfn); + + if (!start_nr || online_section_nr(start_nr)) + return 0; + + while (start_nr-- > 0) { + if (online_section_nr(start_nr)) + return section_nr_to_pfn(start_nr) + PAGES_PER_SECTION; + } + + return 0; +} #else static unsigned long skip_offline_sections(unsigned long start_pfn) { return 0; } + +static unsigned long skip_offline_sections_reverse(unsigned long start_pfn) +{ + return 0; +} #endif /* @@ -1668,8 +1693,15 @@ static void isolate_freepages(struct compact_control *cc) page = pageblock_pfn_to_page(block_start_pfn, block_end_pfn, zone); - if (!page) + if (!page) { + unsigned long next_pfn; + + next_pfn = skip_offline_sections_reverse(block_start_pfn); + if (next_pfn) + block_start_pfn = max(next_pfn, low_pfn); + continue; + } /* Check the block is suitable for migration */ if (!suitable_migration_target(cc, page)) -- cgit v1.2.3