The quilt patch titled
Subject: mm: compaction: skip memory hole rapidly when isolating migratable pages
has been removed from the -mm tree. Its filename was
mm-compaction-skip-memory-hole-rapidly-when-isolating-migratable-pages.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Subject: mm: compaction: skip memory hole rapidly when isolating migratable pages
Date: Wed, 14 Jun 2023 16:40:20 +0800
On some machines, the normal zone can have a large memory hole like below
memory layout, and we can see the range from 0x100000000 to 0x1800000000
is a hole. So when isolating some migratable pages, the scanner can meet
the hole and it will take more time to skip the large hole. From my
measurement, I can see the isolation scanner will take 80us ~ 100us to
skip the large hole [0x100000000 - 0x1800000000].
So adding a new helper to fast search next online memory section to skip
the large hole can help to find next suitable pageblock efficiently. With
this patch, I can see the large hole scanning only takes < 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]
[baolin.wang@xxxxxxxxxxxxxxxxx: limit next_ptn to not exceed cc->free_pfn]
Link: https://lkml.kernel.org/r/a1d859c28af0c7e85e91795e7473f553eb180a9d.1686813379.git.baolin.wang@xxxxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/75b4c8ca36bf44ad8c42bf0685ac19d272e426ec.1686705221.git.baolin.wang@xxxxxxxxxxxxxxxxx
Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Acked-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/compaction.c | 35 ++++++++++++++++++++++++++++++++++-
1 file changed, 34 insertions(+), 1 deletion(-)
--- a/mm/compaction.c~mm-compaction-skip-memory-hole-rapidly-when-isolating-migratable-pages
+++ a/mm/compaction.c
@@ -229,6 +229,33 @@ static void reset_cached_positions(struc
pageblock_start_pfn(zone_end_pfn(zone) - 1);
}
+#ifdef CONFIG_SPARSEMEM
+/*
+ * If the PFN falls into an offline section, return the start PFN of the
+ * next online section. If the PFN falls into an online section or if
+ * there is no next online section, return 0.
+ */
+static unsigned long skip_offline_sections(unsigned long start_pfn)
+{
+ unsigned long start_nr = pfn_to_section_nr(start_pfn);
+
+ if (online_section_nr(start_nr))
+ return 0;
+
+ while (++start_nr <= __highest_present_section_nr) {
+ if (online_section_nr(start_nr))
+ return section_nr_to_pfn(start_nr);
+ }
+
+ return 0;
+}
+#else
+static unsigned long skip_offline_sections(unsigned long start_pfn)
+{
+ return 0;
+}
+#endif
+
/*
* Compound pages of >= pageblock_order should consistently be skipped until
* released. It is always pointless to compact pages of such order (if they are
@@ -1955,8 +1982,14 @@ static isolate_migrate_t isolate_migrate
page = pageblock_pfn_to_page(block_start_pfn,
block_end_pfn, cc->zone);
- if (!page)
+ if (!page) {
+ unsigned long next_pfn;
+
+ next_pfn = skip_offline_sections(block_start_pfn);
+ if (next_pfn)
+ block_end_pfn = min(next_pfn, cc->free_pfn);
continue;
+ }
/*
* If isolation recently failed, do not retry. Only check the
_
Patches currently in -mm which might be from baolin.wang@xxxxxxxxxxxxxxxxx are
