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Date: Sat, 08 Nov 2014 03:58:09 +0300
From: Timofey Titovets <nefelim4ag@...il.com>
To: Linux Kernel <linux-kernel@...r.kernel.org>
CC: linux-mm@...ck.org, marco.antonio.780@...il.com,
Timofey Titovets <nefelim4ag@...il.com>
Subject: [RFC PATCH] KSM: Auto add flag new VMA as VM_MERGEABLE
Hi list.
This is a small patch what allow ksm dedupe "whole" system memory.
I think what people with tiny pc and android developers will be happy
after this patch.
I just like clear memory =].
I have tested it and it working very good. For testing apply it and
enable ksm:
echo 1 | sudo tee /sys/kernel/mm/ksm/run
This show how much memory saved:
echo $[$(cat /sys/kernel/mm/ksm/pages_shared)*$(getconf PAGE_SIZE)/1024 ]KB
(i use linux-next-git 20141031)
It add very small overhead to mmap call's.
Please check my code, may be i should move new functions to other file?
I think about sysfs switcher like:
/sys/kernel/mm/ksm/mark_new_vma # 0 or 1 if 1 new vma will be marked
like VM_MERGEABLE.
Can you advise me something?
I implement 2 new functions:
ksm_vm_flags_mod() - working only in mm/mmap.c file, change default flags
ksm_vma_add_new() - add new created vma to ksm internal tree
If you see broken patch lines i have also attach patch.
From db8ad0877146a69e1e5d5ab98825cefcf44a95bb Mon Sep 17 00:00:00 2001
From: Timofey Titovets <nefelim4ag@...il.com>
Date: Sat, 8 Nov 2014 03:02:52 +0300
Subject: [PATCH] KSM: Add auto flag new VMA as VM_MERGEABLE
Signed-off-by: Timofey Titovets <nefelim4ag@...il.com>
---
include/linux/ksm.h | 31 +++++++++++++++++++++++++++++++
mm/mmap.c | 17 +++++++++++++++++
2 files changed, 48 insertions(+)
diff --git a/include/linux/ksm.h b/include/linux/ksm.h
index 3be6bb1..c3fff64 100644
--- a/include/linux/ksm.h
+++ b/include/linux/ksm.h
@@ -76,6 +76,29 @@ struct page *ksm_might_need_to_copy(struct page *page,
int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc);
void ksm_migrate_page(struct page *newpage, struct page *oldpage);
+/*
+ * Allow to mark new vma as VM_MERGEABLE
+ */
+#ifndef VM_SAO
+#define VM_SAO 0
+#endif
+static inline void ksm_vm_flags_mod(unsigned long *vm_flags)
+{
+ if (*vm_flags & (VM_MERGEABLE | VM_SHARED | VM_MAYSHARE |
+ VM_PFNMAP | VM_IO | VM_DONTEXPAND |
+ VM_HUGETLB | VM_NONLINEAR | VM_MIXEDMAP | VM_SAO) )
+ return;
+ *vm_flags |= VM_MERGEABLE;
+}
+
+static inline void ksm_vma_add_new(struct vm_area_struct *vma)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ if (!test_bit(MMF_VM_MERGEABLE, &mm->flags)) {
+ __ksm_enter(mm);
+ }
+}
+
#else /* !CONFIG_KSM */
static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
@@ -92,6 +115,14 @@ static inline int PageKsm(struct page *page)
return 0;
}
+static inline void ksm_vm_flags_mod(unsigned long *vm_flags_p)
+{
+}
+
+void ksm_vma_add_new(struct vm_area_struct *vma)
+{
+}
+
#ifdef CONFIG_MMU
static inline int ksm_madvise(struct vm_area_struct *vma, unsigned
long start,
unsigned long end, int advice, unsigned long *vm_flags)
diff --git a/mm/mmap.c b/mm/mmap.c
index 7f85520..ce0073e 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -41,6 +41,7 @@
#include <linux/notifier.h>
#include <linux/memory.h>
#include <linux/printk.h>
+#include <linux/ksm.h>
#include <asm/uaccess.h>
#include <asm/cacheflush.h>
@@ -911,10 +912,14 @@ again: remove_next = 1 + (end > next->vm_end);
vma_gap_update(next);
else
mm->highest_vm_end = end;
+ } else {
+ if (next && !insert)
+ ksm_vma_add_new(next);
}
if (insert && file)
uprobe_mmap(insert);
+ ksm_vma_add_new(vma);
validate_mm(mm);
return 0;
@@ -1307,6 +1312,9 @@ unsigned long do_mmap_pgoff(struct file *file,
unsigned long addr,
vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
+ /* If ksm is enabled, we add VM_MERGABLE to new VMAs. */
+ ksm_vm_flags_mod(&vm_flags);
+
if (flags & MAP_LOCKED)
if (!can_do_mlock())
return -EPERM;
@@ -1648,6 +1656,7 @@ munmap_back:
allow_write_access(file);
}
file = vma->vm_file;
+ ksm_vma_add_new(vma);
out:
perf_event_mmap(vma);
@@ -2484,6 +2493,8 @@ static int __split_vma(struct mm_struct *mm,
struct vm_area_struct *vma,
else
err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
+ ksm_vma_add_new(vma);
+
/* Success. */
if (!err)
return 0;
@@ -2659,6 +2670,9 @@ static unsigned long do_brk(unsigned long addr,
unsigned long len)
if (error)
return error;
+ /* If ksm is enabled, we add VM_MERGABLE to new VMAs. */
+ ksm_vm_flags_mod(&flags);
+
/*
* mm->mmap_sem is required to protect against another thread
* changing the mappings in case we sleep.
@@ -2708,6 +2722,7 @@ static unsigned long do_brk(unsigned long addr,
unsigned long len)
vma->vm_flags = flags;
vma->vm_page_prot = vm_get_page_prot(flags);
vma_link(mm, vma, prev, rb_link, rb_parent);
+ ksm_vma_add_new(vma);
out:
perf_event_mmap(vma);
mm->total_vm += len >> PAGE_SHIFT;
@@ -2887,6 +2902,7 @@ struct vm_area_struct *copy_vma(struct
vm_area_struct **vmap,
new_vma->vm_ops->open(new_vma);
vma_link(mm, new_vma, prev, rb_link, rb_parent);
*need_rmap_locks = false;
+ ksm_vma_add_new(new_vma);
}
}
return new_vma;
@@ -3004,6 +3020,7 @@ static struct vm_area_struct
*__install_special_mapping(
mm->total_vm += len >> PAGE_SHIFT;
perf_event_mmap(vma);
+ ksm_vma_add_new(vma);
return vma;
--
2.1.3
View attachment "0001-KSM-Add-auto-flag-new-VMA-as-VM_MERGEABLE.patch" of type "text/x-patch" (4222 bytes)
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