On Mon, 29 Mar 2010 12:03:59 +0900
Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx> wrote:
> This patch adds support for moving charge of shmem and swap of it. It's enabled
> by setting bit 2 of <target cgroup>/memory.move_charge_at_immigrate.
>
> Signed-off-by: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
> ---
> Documentation/cgroups/memory.txt | 7 +++-
> include/linux/swap.h | 5 +++
> mm/memcontrol.c | 52 +++++++++++++++++++++++++------------
> mm/shmem.c | 37 +++++++++++++++++++++++++++
> 4 files changed, 82 insertions(+), 19 deletions(-)
>
> diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
> index f53d220..b197d60 100644
> --- a/Documentation/cgroups/memory.txt
> +++ b/Documentation/cgroups/memory.txt
> @@ -464,13 +464,16 @@ charges should be moved.
> -----+------------------------------------------------------------------------
> 1 | A charge of file cache mmap'ed by the target task. Those pages must be
> | mmap'ed only by the target task.
> + -----+------------------------------------------------------------------------
> + 2 | A charge of a tmpfs page(or swap of it) mmap'ed by the target task. A
> + | typical use case of it is ipc shared memory. It must be mmap'ed by the
> + | target task, but unlike above 2 cases, the task may not be the only one.
> + | You must enable Swap Extension(see 2.4) to enable move of swap charges.
>
> Note: Those pages and swaps must be charged to the old cgroup.
> -Note: More type of pages(e.g. shmem) will be supported by other bits in future.
>
> 8.3 TODO
>
> -- Add support for other types of pages(e.g. file cache, shmem, etc.).
> - Implement madvise(2) to let users decide the vma to be moved or not to be
> moved.
> - All of moving charge operations are done under cgroup_mutex. It's not good
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index 1f59d93..94ec325 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -285,6 +285,11 @@ extern void kswapd_stop(int nid);
> extern int shmem_unuse(swp_entry_t entry, struct page *page);
> #endif /* CONFIG_MMU */
>
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR
> +extern void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff,
> + struct page **pagep, swp_entry_t *ent);
> +#endif
> +
> extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);
>
> #ifdef CONFIG_SWAP
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 66d2704..99a496c 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -251,6 +251,7 @@ struct mem_cgroup {
> enum move_type {
> MOVE_CHARGE_TYPE_ANON, /* private anonymous page and swap of it */
> MOVE_CHARGE_TYPE_FILE, /* private file caches */
> + MOVE_CHARGE_TYPE_SHMEM, /* shared memory and swap of it */
> NR_MOVE_TYPE,
> };
>
> @@ -4195,12 +4196,30 @@ static int is_target_pte_for_mc(struct vm_area_struct *vma,
> &mc.to->move_charge_at_immigrate);
> bool move_file = test_bit(MOVE_CHARGE_TYPE_FILE,
> &mc.to->move_charge_at_immigrate);
> + bool move_shmem = test_bit(MOVE_CHARGE_TYPE_SHMEM,
> + &mc.to->move_charge_at_immigrate);
> + bool is_shmem = false;
>
> if (!pte_present(ptent)) {
> - /* TODO: handle swap of shmes/tmpfs */
> - if (pte_none(ptent) || pte_file(ptent))
> - return 0;
> - else if (is_swap_pte(ptent)) {
> + if (pte_none(ptent) || pte_file(ptent)) {
> + struct inode *inode;
> + struct address_space *mapping;
> + pgoff_t pgoff = 0;
> +
> + if (!vma->vm_file)
> + return 0;
> + mapping = vma->vm_file->f_mapping;
> + if (!move_shmem || !mapping_cap_swap_backed(mapping))
> + return 0;
> +
> + if (pte_none(ptent))
> + pgoff = linear_page_index(vma, addr);
> + if (pte_file(ptent))
> + pgoff = pte_to_pgoff(ptent);
Hmm...then, a shmem page is moved even if the task doesn't do page-fault.
Could you clarify
"All pages in the range mapped by a task will be moved to the new group
even if the task doesn't do page fault, i.e. not tasks' RSS."
?
Thanks,
-Kame
> + inode = vma->vm_file->f_path.dentry->d_inode;
> + mem_cgroup_get_shmem_target(inode, pgoff, &page, &ent);
> + is_shmem = true;
> + } else if (is_swap_pte(ptent)) {
> ent = pte_to_swp_entry(ptent);
> if (!move_anon || non_swap_entry(ent))
> return 0;
> @@ -4210,26 +4229,22 @@ static int is_target_pte_for_mc(struct vm_area_struct *vma,
> page = vm_normal_page(vma, addr, ptent);
> if (!page || !page_mapped(page))
> return 0;
> - /*
> - * TODO: We don't move charges of shmem/tmpfs pages for now.
> - */
> if (PageAnon(page)) {
> if (!move_anon)
> return 0;
> } else if (page_is_file_cache(page)) {
> if (!move_file)
> return 0;
> - } else
> - return 0;
> + } else {
> + if (!move_shmem)
> + return 0;
> + is_shmem = true;
> + }
> if (!get_page_unless_zero(page))
> return 0;
> usage_count = page_mapcount(page);
> }
> - if (usage_count > 1) {
> - /*
> - * TODO: We don't move charges of shared(used by multiple
> - * processes) pages for now.
> - */
> + if (usage_count > 1 && !is_shmem) {
> if (page)
> put_page(page);
> return 0;
> @@ -4284,6 +4299,8 @@ static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
>
> down_read(&mm->mmap_sem);
> for (vma = mm->mmap; vma; vma = vma->vm_next) {
> + bool move_shmem = test_bit(MOVE_CHARGE_TYPE_SHMEM,
> + &mc.to->move_charge_at_immigrate);
> struct mm_walk mem_cgroup_count_precharge_walk = {
> .pmd_entry = mem_cgroup_count_precharge_pte_range,
> .mm = mm,
> @@ -4292,7 +4309,7 @@ static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
> if (is_vm_hugetlb_page(vma))
> continue;
> /* TODO: We don't move charges of shmem/tmpfs pages for now. */
> - if (vma->vm_flags & VM_SHARED)
> + if ((vma->vm_flags & VM_SHARED) && !move_shmem)
> continue;
> walk_page_range(vma->vm_start, vma->vm_end,
> &mem_cgroup_count_precharge_walk);
> @@ -4483,6 +4500,8 @@ static void mem_cgroup_move_charge(struct mm_struct *mm)
> down_read(&mm->mmap_sem);
> for (vma = mm->mmap; vma; vma = vma->vm_next) {
> int ret;
> + bool move_shmem = test_bit(MOVE_CHARGE_TYPE_SHMEM,
> + &mc.to->move_charge_at_immigrate);
> struct mm_walk mem_cgroup_move_charge_walk = {
> .pmd_entry = mem_cgroup_move_charge_pte_range,
> .mm = mm,
> @@ -4490,8 +4509,7 @@ static void mem_cgroup_move_charge(struct mm_struct *mm)
> };
> if (is_vm_hugetlb_page(vma))
> continue;
> - /* TODO: We don't move charges of shmem/tmpfs pages for now. */
> - if (vma->vm_flags & VM_SHARED)
> + if ((vma->vm_flags & VM_SHARED) && !move_shmem)
> continue;
> ret = walk_page_range(vma->vm_start, vma->vm_end,
> &mem_cgroup_move_charge_walk);
> diff --git a/mm/shmem.c b/mm/shmem.c
> index dde4363..cb87365 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -2701,3 +2701,40 @@ int shmem_zero_setup(struct vm_area_struct *vma)
> vma->vm_ops = &shmem_vm_ops;
> return 0;
> }
> +
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR
> +/**
> + * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file
> + * @inode: the inode to be searched
> + * @pgoff: the offset to be searched
> + * @pagep: the pointer for the found page to be stored
> + * @ent: the pointer for the found swap entry to be stored
> + *
> + * If a page is found, refcount of it is incremented. Callers should handle
> + * these refcount.
> + */
> +void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff,
> + struct page **pagep, swp_entry_t *ent)
> +{
> + swp_entry_t entry = { .val = 0 }, *ptr;
> + struct page *page = NULL;
> + struct shmem_inode_info *info = SHMEM_I(inode);
> +
> + if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
> + goto out;
> +
> + spin_lock(&info->lock);
> + ptr = shmem_swp_entry(info, pgoff, NULL);
> + if (ptr && ptr->val) {
> + entry.val = ptr->val;
> + page = find_get_page(&swapper_space, entry.val);
> + } else
> + page = find_get_page(inode->i_mapping, pgoff);
> + if (ptr)
> + shmem_swp_unmap(ptr);
> + spin_unlock(&info->lock);
> +out:
> + *pagep = page;
> + *ent = entry;
> +}
> +#endif
> --
> 1.6.4
>
>
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