Baolin Wang (1): mm: page_alloc: use the correct THP order for THP PCP
Liu Shixin (1): mm: prepare more high-order pages to be stored on the per-cpu lists
include/linux/mmzone.h | 4 +++- mm/page_alloc.c | 6 +++--- 2 files changed, 6 insertions(+), 4 deletions(-)
From: Baolin Wang baolin.wang@linux.alibaba.com
next inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I9OCYO CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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Commit 44042b449872 ("mm/page_alloc: allow high-order pages to be stored on the per-cpu lists") extends the PCP allocator to store THP pages, and it determines whether to cache THP pages in PCP by comparing with pageblock_order. But the pageblock_order is not always equal to THP order. It might also be MAX_PAGE_ORDER, which could prevent PCP from caching THP pages.
Therefore, using HPAGE_PMD_ORDER instead to determine the need for caching THP for PCP will fix this issue
Link: https://lkml.kernel.org/r/a25c9e14cd03907d5978b60546a69e6aa3fc2a7d.171215183... Fixes: 44042b449872 ("mm/page_alloc: allow high-order pages to be stored on the per-cpu lists") Signed-off-by: Baolin Wang baolin.wang@linux.alibaba.com Acked-by: Vlastimil Babka vbabka@suse.cz Cc: Mel Gorman mgorman@techsingularity.net Reviewed-by: Barry Song baohua@kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Liu Shixin liushixin2@huawei.com --- mm/page_alloc.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 95bd8f6f7889..4652dc453964 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -529,7 +529,7 @@ static inline unsigned int order_to_pindex(int migratetype, int order) { #ifdef CONFIG_TRANSPARENT_HUGEPAGE if (order > PAGE_ALLOC_COSTLY_ORDER) { - VM_BUG_ON(order != pageblock_order); + VM_BUG_ON(order != HPAGE_PMD_ORDER); return NR_LOWORDER_PCP_LISTS; } #else @@ -545,7 +545,7 @@ static inline int pindex_to_order(unsigned int pindex)
#ifdef CONFIG_TRANSPARENT_HUGEPAGE if (pindex == NR_LOWORDER_PCP_LISTS) - order = pageblock_order; + order = HPAGE_PMD_ORDER; #else VM_BUG_ON(order > PAGE_ALLOC_COSTLY_ORDER); #endif @@ -558,7 +558,7 @@ static inline bool pcp_allowed_order(unsigned int order) if (order <= PAGE_ALLOC_COSTLY_ORDER) return true; #ifdef CONFIG_TRANSPARENT_HUGEPAGE - if (order == pageblock_order) + if (order == HPAGE_PMD_ORDER) return true; #endif return false;
hulk inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I9OCYO
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Both the file pages and anonymous pages support large folio, high-order pages except HPAGE_PMD_ORDER(PMD_SHIFT - PAGE_SHIFT) will be allocated frequently which will increase the zone lock contention, allow high-order pages on pcp lists could alleviate the big zone lock contention. Similar with lower order pages(order <= 3), allows one more high-order pages to be stored on the per-cpu lists.
But as commit 44042b449872 ("mm/page_alloc: allow high-order pages to be stored on the per-cpu lists") pointed, it may not win in all the scenes, so this don't allow higher-order pages to be added to PCP list, it will add a control to enable or disable it in future.
The struct per_cpu_pages increases in size from 256(4 cache lines) to 320 bytes (5 cache lines) on arm64 with defconfig.
Signed-off-by: Kefeng Wang wangkefeng.wang@huawei.com Signed-off-by: Liu Shixin liushixin2@huawei.com --- include/linux/mmzone.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index a394cbe31c59..bcf4fd4ab824 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -684,10 +684,12 @@ enum zone_watermarks { */ #ifdef CONFIG_TRANSPARENT_HUGEPAGE #define NR_PCP_THP 1 +#define NR_PCP_ORDERS (PAGE_ALLOC_COSTLY_ORDER + 2) #else #define NR_PCP_THP 0 +#define NR_PCP_ORDERS (PAGE_ALLOC_COSTLY_ORDER + 1) #endif -#define NR_LOWORDER_PCP_LISTS (MIGRATE_PCPTYPES * (PAGE_ALLOC_COSTLY_ORDER + 1)) +#define NR_LOWORDER_PCP_LISTS (MIGRATE_PCPTYPES * NR_PCP_ORDERS) #define NR_PCP_LISTS (NR_LOWORDER_PCP_LISTS + NR_PCP_THP)
#define min_wmark_pages(z) (z->_watermark[WMARK_MIN] + z->watermark_boost)
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