The patch titled
hugetlb: forget rss with pt sharing
has been added to the -mm tree. Its filename is
htlb-forget-rss-with-pt-sharing.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: hugetlb: forget rss with pt sharing
From: "Chen, Kenneth W" <kenneth.w.chen@xxxxxxxxx>
Imprecise RSS accounting is an irritating ill effect with pt sharing.
After consulted with several VM experts, I have tried various methods to
solve that problem: (1) iterate through all mm_structs that share the PT
and increment count; (2) keep RSS count in page table structure and then
sum them up at reporting time. None of the above methods yield any
satisfactory implementation.
Since process RSS accounting is pure information only, I propose we don't
count them at all for hugetlb page. rlimit has such field, though there is
absolutely no enforcement on limiting that resource. One other method is
to account all RSS at hugetlb mmap time regardless they are faulted or not.
I opt for the simplicity of no accounting at all.
Signed-off-by: Ken Chen <kenneth.w.chen@xxxxxxxxx>
Cc: Hugh Dickins <hugh@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
mm/hugetlb.c | 8 --------
1 file changed, 8 deletions(-)
diff -puN mm/hugetlb.c~htlb-forget-rss-with-pt-sharing mm/hugetlb.c
--- a/mm/hugetlb.c~htlb-forget-rss-with-pt-sharing
+++ a/mm/hugetlb.c
@@ -344,7 +344,6 @@ int copy_hugetlb_page_range(struct mm_st
entry = *src_pte;
ptepage = pte_page(entry);
get_page(ptepage);
- add_mm_counter(dst, file_rss, HPAGE_SIZE / PAGE_SIZE);
set_huge_pte_at(dst, addr, dst_pte, entry);
}
spin_unlock(&src->page_table_lock);
@@ -372,10 +371,6 @@ void __unmap_hugepage_range(struct vm_ar
BUG_ON(end & ~HPAGE_MASK);
spin_lock(&mm->page_table_lock);
-
- /* Update high watermark before we lower rss */
- update_hiwater_rss(mm);
-
for (address = start; address < end; address += HPAGE_SIZE) {
ptep = huge_pte_offset(mm, address);
if (!ptep)
@@ -390,9 +385,7 @@ void __unmap_hugepage_range(struct vm_ar
page = pte_page(pte);
list_add(&page->lru, &page_list);
- add_mm_counter(mm, file_rss, (int) -(HPAGE_SIZE / PAGE_SIZE));
}
-
spin_unlock(&mm->page_table_lock);
flush_tlb_range(vma, start, end);
list_for_each_entry_safe(page, tmp, &page_list, lru) {
@@ -507,7 +500,6 @@ retry:
if (!pte_none(*ptep))
goto backout;
- add_mm_counter(mm, file_rss, HPAGE_SIZE / PAGE_SIZE);
new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
&& (vma->vm_flags & VM_SHARED)));
set_huge_pte_at(mm, address, ptep, new_pte);
_
Patches currently in -mm which might be from kenneth.w.chen@xxxxxxxxx are
shared-page-table-for-hugetlb-page-v4.patch
htlb-forget-rss-with-pt-sharing.patch
-
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