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Date: Thu, 13 Apr 2023 13:55:47 +0800
From: Yang Yang <yang.yang29@....com.cn>
To: akpm@...ux-foundation.org, david@...hat.com
Cc: yang.yang29@....com.cn, imbrenda@...ux.ibm.com,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
ran.xiaokai@....com.cn, xu.xin.sc@...il.com, xu.xin16@....com.cn,
Xuexin Jiang <jiang.xuexin@....com.cn>
Subject: [PATCH v7 3/6] ksm: add ksm zero pages for each process
From: xu xin <xu.xin16@....com.cn>
As the number of ksm zero pages is not included in ksm_merging_pages per
process when enabling use_zero_pages, it's unclear of how many actual
pages are merged by KSM. To let users accurately estimate their memory
demands when unsharing KSM zero-pages, it's necessary to show KSM zero-
pages per process. In addition, it help users to know the actual KSM
profit because KSM-placed zero pages are also benefit from KSM.
since unsharing zero pages placed by KSM accurately is achieved, then
tracking empty pages merging and unmerging is not a difficult thing any
longer.
Since we already have /proc/<pid>/ksm_stat, just add the information of
'ksm_zero_pages' in it.
Signed-off-by: xu xin <xu.xin16@....com.cn>
Cc: Claudio Imbrenda <imbrenda@...ux.ibm.com>
Cc: David Hildenbrand <david@...hat.com>
Cc: Xuexin Jiang <jiang.xuexin@....com.cn>
Cc: Xiaokai Ran <ran.xiaokai@....com.cn>
Cc: Yang Yang <yang.yang29@....com.cn>
---
fs/proc/base.c | 3 +++
include/linux/ksm.h | 10 ++++++----
include/linux/mm_types.h | 11 +++++++++--
mm/ksm.c | 2 +-
mm/memory.c | 4 ++--
5 files changed, 21 insertions(+), 9 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index ab9fa5b1b6be..235182cd143d 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -3211,6 +3211,9 @@ static int proc_pid_ksm_stat(struct seq_file *m, struct pid_namespace *ns,
seq_printf(m, "ksm_merging_pages %lu\n", mm->ksm_merging_pages);
seq_printf(m, "ksm_merge_type %s\n", ksm_merge_type(mm));
seq_printf(m, "ksm_process_profit %ld\n", ksm_process_profit(mm));
+#ifdef CONFIG_KSM_ZERO_PAGES_TRACK
+ seq_printf(m, "ksm_zero_pages %lu\n", mm->ksm_zero_pages);
+#endif
mmput(mm);
}
diff --git a/include/linux/ksm.h b/include/linux/ksm.h
index ea628d2a9105..2da40af9ad4d 100644
--- a/include/linux/ksm.h
+++ b/include/linux/ksm.h
@@ -100,22 +100,24 @@ static inline void folio_migrate_ksm(struct folio *newfolio, struct folio *old)
#define set_pte_ksm_zero(pte) pte_mkdirty(pte_mkspecial(pte))
#define is_ksm_zero_pte(pte) (is_zero_pfn(pte_pfn(pte)) && pte_dirty(pte))
extern unsigned long ksm_zero_pages;
-static inline void inc_ksm_zero_pages(void)
+static inline void inc_ksm_zero_pages(struct mm_struct *mm)
{
ksm_zero_pages++;
+ mm->ksm_zero_pages++;
}
-static inline void dec_ksm_zero_pages(void)
+static inline void dec_ksm_zero_pages(struct mm_struct *mm)
{
ksm_zero_pages--;
+ mm->ksm_zero_pages--;
}
#else /* !CONFIG_KSM_ZERO_PAGES_TRACK */
#define set_pte_ksm_zero(pte) pte_mkspecial(pte)
#define is_ksm_zero_pte(pte) 0
-static inline void inc_ksm_zero_pages(void)
+static inline void inc_ksm_zero_pages(struct mm_struct *mm)
{
}
-static inline void dec_ksm_zero_pages(void)
+static inline void dec_ksm_zero_pages(struct mm_struct *mm)
{
}
#endif /* CONFIG_KSM_ZERO_PAGES_TRACK */
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 3fc9e680f174..2e72329ed1a2 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -766,7 +766,7 @@ struct mm_struct {
#ifdef CONFIG_KSM
/*
* Represent how many pages of this process are involved in KSM
- * merging.
+ * merging (not including ksm_zero_pages).
*/
unsigned long ksm_merging_pages;
/*
@@ -774,7 +774,14 @@ struct mm_struct {
* including merged and not merged.
*/
unsigned long ksm_rmap_items;
-#endif
+#ifdef CONFIG_KSM_ZERO_PAGES_TRACK
+ /*
+ * Represent how many empty pages are merged with kernel zero
+ * pages when enabling KSM use_zero_pages.
+ */
+ unsigned long ksm_zero_pages;
+#endif /* CONFIG_KSM_ZERO_PAGES_TRACK */
+#endif /* CONFIG_KSM */
#ifdef CONFIG_LRU_GEN
struct {
/* this mm_struct is on lru_gen_mm_list */
diff --git a/mm/ksm.c b/mm/ksm.c
index 232680393741..7867fae3c61c 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1248,7 +1248,7 @@ static int replace_page(struct vm_area_struct *vma, struct page *page,
} else {
newpte = set_pte_ksm_zero(pfn_pte(page_to_pfn(kpage),
vma->vm_page_prot));
- inc_ksm_zero_pages();
+ inc_ksm_zero_pages(mm);
/*
* We're replacing an anonymous page with a zero page, which is
* not anonymous. We need to do proper accounting otherwise we
diff --git a/mm/memory.c b/mm/memory.c
index 76598287280f..ec89b81a14fd 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1418,7 +1418,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
ptent);
if (unlikely(!page)) {
if (is_ksm_zero_pte(ptent))
- dec_ksm_zero_pages();
+ dec_ksm_zero_pages(mm);
continue;
}
@@ -3122,7 +3122,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
}
} else {
if (is_ksm_zero_pte(vmf->orig_pte))
- dec_ksm_zero_pages();
+ dec_ksm_zero_pages(mm);
inc_mm_counter(mm, MM_ANONPAGES);
}
flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
--
2.15.2
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