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[PATCH] mm: batch updating mm_counters 

tlb_finish_mmu used to batch zap_pte_range's update of mm rss, which may be
worthwhile if the mm is contended, and would reduce atomic operations if the
counts were atomic.  Let zap_pte_range now batch its updates to file_rss and
anon_rss, per page-table in case we drop the lock outside; and copy_pte_range
batch them too.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Hugh Dickins 2005-10-29 18:16:05 -07:00 committed by Linus Torvalds
parent 4294621f41
commit ae85976233
1 changed files with 32 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

47
mm/memory.c
View File

@ -332,6 +332,16 @@ out:
return pte_offset_kernel(pmd, address);
}
static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss)
{
if (file_rss)
add_mm_counter(mm, file_rss, file_rss);
if (anon_rss)
add_mm_counter(mm, anon_rss, anon_rss);
}
#define NO_RSS 2 /* Increment neither file_rss nor anon_rss */
/*
* copy one vm_area from one task to the other. Assumes the page tables
* already present in the new task to be cleared in the whole range
@ -341,7 +351,7 @@ out:
* but may be dropped within p[mg]d_alloc() and pte_alloc_map().
*/
static inline void
static inline int
copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
pte_t *dst_pte, pte_t *src_pte, unsigned long vm_flags,
unsigned long addr)
@ -349,6 +359,7 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
pte_t pte = *src_pte;
struct page *page;
unsigned long pfn;
int anon = NO_RSS;
/* pte contains position in swap or file, so copy. */
if (unlikely(!pte_present(pte))) {
@ -361,8 +372,7 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
spin_unlock(&mmlist_lock);
}
}
set_pte_at(dst_mm, addr, dst_pte, pte);
return;
goto out_set_pte;
}
pfn = pte_pfn(pte);
@ -375,10 +385,8 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
if (pfn_valid(pfn))
page = pfn_to_page(pfn);
if (!page || PageReserved(page)) {
set_pte_at(dst_mm, addr, dst_pte, pte);
return;
}
if (!page || PageReserved(page))
goto out_set_pte;
/*
* If it's a COW mapping, write protect it both
@ -397,12 +405,12 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
pte = pte_mkclean(pte);
pte = pte_mkold(pte);
get_page(page);
if (PageAnon(page))
inc_mm_counter(dst_mm, anon_rss);
else
inc_mm_counter(dst_mm, file_rss);
set_pte_at(dst_mm, addr, dst_pte, pte);
page_dup_rmap(page);
anon = !!PageAnon(page);
out_set_pte:
set_pte_at(dst_mm, addr, dst_pte, pte);
return anon;
}
static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
@ -412,8 +420,10 @@ static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
pte_t *src_pte, *dst_pte;
unsigned long vm_flags = vma->vm_flags;
int progress = 0;
int rss[NO_RSS+1], anon;
again:
rss[1] = rss[0] = 0;
dst_pte = pte_alloc_map(dst_mm, dst_pmd, addr);
if (!dst_pte)
return -ENOMEM;
@ -436,13 +446,16 @@ again:
progress++;
continue;
}
copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vm_flags, addr);
anon = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
vm_flags, addr);
rss[anon]++;
progress += 8;
} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
spin_unlock(&src_mm->page_table_lock);
pte_unmap_nested(src_pte - 1);
pte_unmap(dst_pte - 1);
add_mm_rss(dst_mm, rss[0], rss[1]);
cond_resched_lock(&dst_mm->page_table_lock);
if (addr != end)
goto again;
@ -533,6 +546,8 @@ static void zap_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
struct zap_details *details)
{
pte_t *pte;
int file_rss = 0;
int anon_rss = 0;
pte = pte_offset_map(pmd, addr);
do {
@ -576,13 +591,13 @@ static void zap_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
set_pte_at(tlb->mm, addr, pte,
pgoff_to_pte(page->index));
if (PageAnon(page))
dec_mm_counter(tlb->mm, anon_rss);
anon_rss++;
else {
if (pte_dirty(ptent))
set_page_dirty(page);
if (pte_young(ptent))
mark_page_accessed(page);
dec_mm_counter(tlb->mm, file_rss);
file_rss++;
}
page_remove_rmap(page);
tlb_remove_page(tlb, page);
@ -598,6 +613,8 @@ static void zap_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
free_swap_and_cache(pte_to_swp_entry(ptent));
pte_clear_full(tlb->mm, addr, pte, tlb->fullmm);
} while (pte++, addr += PAGE_SIZE, addr != end);
add_mm_rss(tlb->mm, -file_rss, -anon_rss);
pte_unmap(pte - 1);
}