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Message-ID: <20240212163510.859822-2-zi.yan@sent.com>
Date: Mon, 12 Feb 2024 11:35:08 -0500
From: Zi Yan <zi.yan@...t.com>
To: linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Cc: Zi Yan <ziy@...dia.com>,
"Huang, Ying" <ying.huang@...el.com>,
Ryan Roberts <ryan.roberts@....com>,
Andrew Morton <akpm@...ux-foundation.org>,
"Matthew Wilcox (Oracle)" <willy@...radead.org>,
David Hildenbrand <david@...hat.com>,
"Yin, Fengwei" <fengwei.yin@...el.com>,
Yu Zhao <yuzhao@...gle.com>,
Vlastimil Babka <vbabka@...e.cz>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
Johannes Weiner <hannes@...xchg.org>,
Baolin Wang <baolin.wang@...ux.alibaba.com>,
Kemeng Shi <shikemeng@...weicloud.com>,
Mel Gorman <mgorman@...hsingularity.net>,
Rohan Puri <rohan.puri15@...il.com>,
Mcgrof Chamberlain <mcgrof@...nel.org>,
Adam Manzanares <a.manzanares@...sung.com>,
"Vishal Moola (Oracle)" <vishal.moola@...il.com>
Subject: [PATCH v4 1/3] mm/compaction: enable compacting >0 order folios.
From: Zi Yan <ziy@...dia.com>
migrate_pages() supports >0 order folio migration and during compaction,
even if compaction_alloc() cannot provide >0 order free pages,
migrate_pages() can split the source page and try to migrate the base
pages from the split. It can be a baseline and start point for adding
support for compacting >0 order folios.
Signed-off-by: Zi Yan <ziy@...dia.com>
Suggested-by: Huang Ying <ying.huang@...el.com>
Reviewed-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
Tested-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
Cc: Adam Manzanares <a.manzanares@...sung.com>
Cc: David Hildenbrand <david@...hat.com>
Cc: Johannes Weiner <hannes@...xchg.org>
Cc: Kemeng Shi <shikemeng@...weicloud.com>
Cc: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Cc: Luis Chamberlain <mcgrof@...nel.org>
Cc: Matthew Wilcox (Oracle) <willy@...radead.org>
Cc: Mel Gorman <mgorman@...hsingularity.net>
Cc: Ryan Roberts <ryan.roberts@....com>
Cc: Vishal Moola (Oracle) <vishal.moola@...il.com>
Cc: Vlastimil Babka <vbabka@...e.cz>
Cc: Yin Fengwei <fengwei.yin@...el.com>
Cc: Yu Zhao <yuzhao@...gle.com>
---
mm/compaction.c | 66 ++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 52 insertions(+), 14 deletions(-)
diff --git a/mm/compaction.c b/mm/compaction.c
index cc801ce099b4..aa6aad805c4d 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -816,6 +816,21 @@ static bool too_many_isolated(struct compact_control *cc)
return too_many;
}
+/*
+ * 1. if the page order is larger than or equal to target_order (i.e.,
+ * cc->order and when it is not -1 for global compaction), skip it since
+ * target_order already indicates no free page with larger than target_order
+ * exists and later migrating it will most likely fail;
+ *
+ * 2. compacting > pageblock_order pages does not improve memory fragmentation,
+ * skip them;
+ */
+static bool skip_isolation_on_order(int order, int target_order)
+{
+ return (target_order != -1 && order >= target_order) ||
+ order >= pageblock_order;
+}
+
/**
* isolate_migratepages_block() - isolate all migrate-able pages within
* a single pageblock
@@ -947,7 +962,22 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
valid_page = page;
}
- if (PageHuge(page) && cc->alloc_contig) {
+ if (PageHuge(page)) {
+ /*
+ * skip hugetlbfs if we are not compacting for pages
+ * bigger than its order. THPs and other compound pages
+ * are handled below.
+ */
+ if (!cc->alloc_contig) {
+ const unsigned int order = compound_order(page);
+
+ if (order <= MAX_PAGE_ORDER) {
+ low_pfn += (1UL << order) - 1;
+ nr_scanned += (1UL << order) - 1;
+ }
+ goto isolate_fail;
+ }
+ /* for alloc_contig case */
if (locked) {
unlock_page_lruvec_irqrestore(locked, flags);
locked = NULL;
@@ -1008,21 +1038,24 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
}
/*
- * Regardless of being on LRU, compound pages such as THP and
- * hugetlbfs are not to be compacted unless we are attempting
- * an allocation much larger than the huge page size (eg CMA).
- * We can potentially save a lot of iterations if we skip them
- * at once. The check is racy, but we can consider only valid
- * values and the only danger is skipping too much.
+ * Regardless of being on LRU, compound pages such as THP
+ * (hugetlbfs is handled above) are not to be compacted unless
+ * we are attempting an allocation larger than the compound
+ * page size. We can potentially save a lot of iterations if we
+ * skip them at once. The check is racy, but we can consider
+ * only valid values and the only danger is skipping too much.
*/
if (PageCompound(page) && !cc->alloc_contig) {
const unsigned int order = compound_order(page);
- if (likely(order <= MAX_PAGE_ORDER)) {
- low_pfn += (1UL << order) - 1;
- nr_scanned += (1UL << order) - 1;
+ /* Skip based on page order and compaction target order. */
+ if (skip_isolation_on_order(order, cc->order)) {
+ if (order <= MAX_PAGE_ORDER) {
+ low_pfn += (1UL << order) - 1;
+ nr_scanned += (1UL << order) - 1;
+ }
+ goto isolate_fail;
}
- goto isolate_fail;
}
/*
@@ -1165,10 +1198,11 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
}
/*
- * folio become large since the non-locked check,
- * and it's on LRU.
+ * Check LRU folio order under the lock
*/
- if (unlikely(folio_test_large(folio) && !cc->alloc_contig)) {
+ if (unlikely(skip_isolation_on_order(folio_order(folio),
+ cc->order) &&
+ !cc->alloc_contig)) {
low_pfn += folio_nr_pages(folio) - 1;
nr_scanned += folio_nr_pages(folio) - 1;
folio_set_lru(folio);
@@ -1788,6 +1822,10 @@ static struct folio *compaction_alloc(struct folio *src, unsigned long data)
struct compact_control *cc = (struct compact_control *)data;
struct folio *dst;
+ /* this makes migrate_pages() split the source page and retry */
+ if (folio_test_large(src) > 0)
+ return NULL;
+
if (list_empty(&cc->freepages)) {
isolate_freepages(cc);
--
2.43.0
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