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SubjectRe: Fwd: Control page reclaim granularity
Sorry, please forgive me.  This patch has a defect.  When one page is
scaned and flag is clear, all other's flags also are clear too.

Regards,
Zheng

On Tue, Mar 13, 2012 at 02:30:14PM +0800, Zheng Liu wrote:
> This only a first trivial try. If this flag is set, reclaimer just give this
> page one more round trip rather than promote it into active list. Any comments
> or advices are welcomed.
>
> Regards,
> Zheng
>
> [PATCH] mm: per-inode mmaped page reclaim
>
> From: Zheng Liu <wenqing.lz@taobao.com>
>
> In some cases, user wants to control mmaped page reclaim granularity. A new
> flag is added into struct address_space to give the page one more round trip.
> AS_WORKINGSET flag cannot be added in vma->vm_flags because this flag has no
> room for a new flag in 32 bit. Now user can call madvise(2) to set this flag
> for a file. If this flag is set, all pages will be given one more round trip
> when reclaimer tries to shrink pages.
>
> Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
> ---
> include/asm-generic/mman-common.h | 2 ++
> include/linux/pagemap.h | 16 ++++++++++++++++
> mm/madvise.c | 8 ++++++++
> mm/vmscan.c | 15 +++++++++++++++
> 4 files changed, 41 insertions(+), 0 deletions(-)
>
> diff --git a/include/asm-generic/mman-common.h b/include/asm-generic/mman-common.h
> index 787abbb..7d26c9b 100644
> --- a/include/asm-generic/mman-common.h
> +++ b/include/asm-generic/mman-common.h
> @@ -48,6 +48,8 @@
> #define MADV_HUGEPAGE 14 /* Worth backing with hugepages */
> #define MADV_NOHUGEPAGE 15 /* Not worth backing with hugepages */
>
> +#define MADV_WORKINGSET 16 /* give one more round trip */
> +
> /* compatibility flags */
> #define MAP_FILE 0
>
> diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> index cfaaa69..80532a0 100644
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -24,6 +24,7 @@ enum mapping_flags {
> AS_ENOSPC = __GFP_BITS_SHIFT + 1, /* ENOSPC on async write */
> AS_MM_ALL_LOCKS = __GFP_BITS_SHIFT + 2, /* under mm_take_all_locks() */
> AS_UNEVICTABLE = __GFP_BITS_SHIFT + 3, /* e.g., ramdisk, SHM_LOCK */
> + AS_WORKINGSET = __GFP_BITS_SHIFT + 4, /* give one more round trip */
> };
>
> static inline void mapping_set_error(struct address_space *mapping, int error)
> @@ -36,6 +37,21 @@ static inline void mapping_set_error(struct address_space *mapping, int error)
> }
> }
>
> +static inline void mapping_set_workingset(struct address_space *mapping)
> +{
> + set_bit(AS_WORKINGSET, &mapping->flags);
> +}
> +
> +static inline void mapping_clear_workingset(struct address_space *mapping)
> +{
> + clear_bit(AS_WORKINGSET, &mapping->flags);
> +}
> +
> +static inline int mapping_test_workingset(struct address_space *mapping)
> +{
> + return mapping && test_bit(AS_WORKINGSET, &mapping->flags);
> +}
> +
> static inline void mapping_set_unevictable(struct address_space *mapping)
> {
> set_bit(AS_UNEVICTABLE, &mapping->flags);
> diff --git a/mm/madvise.c b/mm/madvise.c
> index 74bf193..8ca6c9b 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
> @@ -77,6 +77,14 @@ static long madvise_behavior(struct vm_area_struct * vma,
> if (error)
> goto out;
> break;
> + case MADV_WORKINGSET:
> + if (vma->vm_file && vma->vm_file->f_mapping) {
> + mapping_set_workingset(vma->vm_file->f_mapping);
> + } else {
> + error = -EPERM;
> + goto out;
> + }
> + break;
> }
>
> if (new_flags == vma->vm_flags) {
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index c52b235..51f745b 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -721,6 +721,15 @@ static enum page_references page_check_references(struct page *page,
> if (vm_flags & VM_LOCKED)
> return PAGEREF_RECLAIM;
>
> + /*
> + * give this page one more round trip because workingset
> + * flag is set.
> + */
> + if (mapping_test_workingset(page_mapping(page))) {
> + mapping_clear_workingset(page_mapping(page));
> + return PAGEREF_KEEP;
> + }
> +
> if (referenced_ptes) {
> if (PageAnon(page))
> return PAGEREF_ACTIVATE;
> @@ -1737,6 +1746,12 @@ static void shrink_active_list(unsigned long nr_to_scan,
> continue;
> }
>
> + if (mapping_test_workingset(page_mapping(page))) {
> + mapping_clear_workingset(page_mapping(page));
> + list_add(&page->lru, &l_active);
> + continue;
> + }
> +
> if (page_referenced(page, 0, mz->mem_cgroup, &vm_flags)) {
> nr_rotated += hpage_nr_pages(page);
> /*
> --
> 1.7.4.1
>


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