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SubjectRe: [PATCH] show per-process swap usage via procfs
From
Hi, Kame.

On Wed, Nov 4, 2009 at 3:24 PM, KAMEZAWA Hiroyuki
<kamezawa.hiroyu@jp.fujitsu.com> wrote:
>
> Passed several tests and one bug was fixed since RFC version.
> This patch is against mmotm.
> =
> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
>
> Now, anon_rss and file_rss is counted as RSS and exported via /proc.
> RSS usage is important information but one more information which
> is often asked by users is "usage of swap".(user support team said.)
>
> This patch counts swap entry usage per process and show it via
> /proc/<pid>/status. I think status file is robust against new entry.
> Then, it is the first candidate..
>
>  After this, /proc/<pid>/status includes following line
>  <snip>
>  VmPeak:   315360 kB
>  VmSize:   315360 kB
>  VmLck:         0 kB
>  VmHWM:    180452 kB
>  VmRSS:    180452 kB
>  VmData:   311624 kB
>  VmStk:        84 kB
>  VmExe:         4 kB
>  VmLib:      1568 kB
>  VmPTE:       640 kB
>  VmSwap:   131240 kB <=== new information
>
> Note:
>  Because this patch catches swap_pte on page table, this will
>  not catch shmem's swapout. It's already accounted in per-shmem
>  inode and we don't need to do more.
>
> Changelog: 2009/11/03
>  - clean up.
>  - fixed initialization bug at fork (init_mm())
>
> Acked-by: Acked-by; David Rientjes <rientjes@google.com>
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> ---
>  fs/proc/task_mmu.c       |    9 ++++++---
>  include/linux/mm_types.h |    1 +
>  kernel/fork.c            |    1 +
>  mm/memory.c              |   30 +++++++++++++++++++++---------
>  mm/rmap.c                |    1 +
>  mm/swapfile.c            |    1 +
>  6 files changed, 31 insertions(+), 12 deletions(-)
>
> Index: mmotm-2.6.32-Nov2/include/linux/mm_types.h
> ===================================================================
> --- mmotm-2.6.32-Nov2.orig/include/linux/mm_types.h
> +++ mmotm-2.6.32-Nov2/include/linux/mm_types.h
> @@ -228,6 +228,7 @@ struct mm_struct {
>         */
>        mm_counter_t _file_rss;
>        mm_counter_t _anon_rss;
> +       mm_counter_t _swap_usage;
>
>        unsigned long hiwater_rss;      /* High-watermark of RSS usage */
>        unsigned long hiwater_vm;       /* High-water virtual memory usage */
> Index: mmotm-2.6.32-Nov2/mm/memory.c
> ===================================================================
> --- mmotm-2.6.32-Nov2.orig/mm/memory.c
> +++ mmotm-2.6.32-Nov2/mm/memory.c
> @@ -376,12 +376,15 @@ int __pte_alloc_kernel(pmd_t *pmd, unsig
>        return 0;
>  }
>
> -static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss)
> +static inline void
> +add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss, int swap_usage)
>  {
>        if (file_rss)
>                add_mm_counter(mm, file_rss, file_rss);
>        if (anon_rss)
>                add_mm_counter(mm, anon_rss, anon_rss);
> +       if (swap_usage)
> +               add_mm_counter(mm, swap_usage, swap_usage);
>  }
>
>  /*
> @@ -597,7 +600,9 @@ copy_one_pte(struct mm_struct *dst_mm, s
>                                                 &src_mm->mmlist);
>                                spin_unlock(&mmlist_lock);
>                        }
> -                       if (is_write_migration_entry(entry) &&
> +                       if (!is_migration_entry(entry))
> +                               rss[2]++;

First thought I come to is that we believe !is_migration_entry(entry) equal
swap entry?
We began supporting HWPOISON.
HWPOISON would be rare event so some less exact swap accouting may
be allowed, I think. Is this enough to jusitfy that?

> +                       else if (is_write_migration_entry(entry) &&
>                                        is_cow_mapping(vm_flags)) {
>                                /*
>                                 * COW mappings require pages in both parent
> @@ -648,11 +653,11 @@ static int copy_pte_range(struct mm_stru
>        pte_t *src_pte, *dst_pte;
>        spinlock_t *src_ptl, *dst_ptl;
>        int progress = 0;
> -       int rss[2];
> +       int rss[3];
>        swp_entry_t entry = (swp_entry_t){0};
>
>  again:
> -       rss[1] = rss[0] = 0;
> +       rss[2] = rss[1] = rss[0] = 0;
>        dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
>        if (!dst_pte)
>                return -ENOMEM;
> @@ -688,7 +693,7 @@ again:
>        arch_leave_lazy_mmu_mode();
>        spin_unlock(src_ptl);
>        pte_unmap_nested(orig_src_pte);
> -       add_mm_rss(dst_mm, rss[0], rss[1]);
> +       add_mm_rss(dst_mm, rss[0], rss[1], rss[2]);
>        pte_unmap_unlock(orig_dst_pte, dst_ptl);
>        cond_resched();
>
> @@ -818,6 +823,7 @@ static unsigned long zap_pte_range(struc
>        spinlock_t *ptl;
>        int file_rss = 0;
>        int anon_rss = 0;
> +       int swap_usage = 0;
>
>        pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
>        arch_enter_lazy_mmu_mode();
> @@ -887,13 +893,18 @@ static unsigned long zap_pte_range(struc
>                if (pte_file(ptent)) {
>                        if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
>                                print_bad_pte(vma, addr, ptent, NULL);
> -               } else if
> -                 (unlikely(!free_swap_and_cache(pte_to_swp_entry(ptent))))
> -                       print_bad_pte(vma, addr, ptent, NULL);
> +               } else {
> +                       swp_entry_t ent = pte_to_swp_entry(ptent);
> +
> +                       if (!is_migration_entry(ent))
> +                               swap_usage--;

ditto

> +                       if (unlikely(!free_swap_and_cache(ent)))
> +                               print_bad_pte(vma, addr, ptent, NULL);
> +               }
>                pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
>        } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
>
> -       add_mm_rss(mm, file_rss, anon_rss);
> +       add_mm_rss(mm, file_rss, anon_rss, swap_usage);
>        arch_leave_lazy_mmu_mode();
>        pte_unmap_unlock(pte - 1, ptl);
>
> @@ -2595,6 +2606,7 @@ static int do_swap_page(struct mm_struct
>         */
>
>        inc_mm_counter(mm, anon_rss);
> +       dec_mm_counter(mm, swap_usage);
>        pte = mk_pte(page, vma->vm_page_prot);
>        if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
>                pte = maybe_mkwrite(pte_mkdirty(pte), vma);
> Index: mmotm-2.6.32-Nov2/mm/swapfile.c
> ===================================================================
> --- mmotm-2.6.32-Nov2.orig/mm/swapfile.c
> +++ mmotm-2.6.32-Nov2/mm/swapfile.c
> @@ -837,6 +837,7 @@ static int unuse_pte(struct vm_area_stru
>        }
>
>        inc_mm_counter(vma->vm_mm, anon_rss);
> +       dec_mm_counter(vma->vm_mm, swap_usage);
>        get_page(page);
>        set_pte_at(vma->vm_mm, addr, pte,
>                   pte_mkold(mk_pte(page, vma->vm_page_prot)));
> Index: mmotm-2.6.32-Nov2/fs/proc/task_mmu.c
> ===================================================================
> --- mmotm-2.6.32-Nov2.orig/fs/proc/task_mmu.c
> +++ mmotm-2.6.32-Nov2/fs/proc/task_mmu.c
> @@ -17,7 +17,7 @@
>  void task_mem(struct seq_file *m, struct mm_struct *mm)
>  {
>        unsigned long data, text, lib;
> -       unsigned long hiwater_vm, total_vm, hiwater_rss, total_rss;
> +       unsigned long hiwater_vm, total_vm, hiwater_rss, total_rss, swap;
>
>        /*
>         * Note: to minimize their overhead, mm maintains hiwater_vm and
> @@ -36,6 +36,7 @@ void task_mem(struct seq_file *m, struct
>        data = mm->total_vm - mm->shared_vm - mm->stack_vm;
>        text = (PAGE_ALIGN(mm->end_code) - (mm->start_code & PAGE_MASK)) >> 10;
>        lib = (mm->exec_vm << (PAGE_SHIFT-10)) - text;
> +       swap = get_mm_counter(mm, swap_usage);
>        seq_printf(m,
>                "VmPeak:\t%8lu kB\n"
>                "VmSize:\t%8lu kB\n"
> @@ -46,7 +47,8 @@ void task_mem(struct seq_file *m, struct
>                "VmStk:\t%8lu kB\n"
>                "VmExe:\t%8lu kB\n"
>                "VmLib:\t%8lu kB\n"
> -               "VmPTE:\t%8lu kB\n",
> +               "VmPTE:\t%8lu kB\n"
> +               "VmSwap:\t%8lu kB\n",
>                hiwater_vm << (PAGE_SHIFT-10),
>                (total_vm - mm->reserved_vm) << (PAGE_SHIFT-10),
>                mm->locked_vm << (PAGE_SHIFT-10),
> @@ -54,7 +56,8 @@ void task_mem(struct seq_file *m, struct
>                total_rss << (PAGE_SHIFT-10),
>                data << (PAGE_SHIFT-10),
>                mm->stack_vm << (PAGE_SHIFT-10), text, lib,
> -               (PTRS_PER_PTE*sizeof(pte_t)*mm->nr_ptes) >> 10);
> +               (PTRS_PER_PTE*sizeof(pte_t)*mm->nr_ptes) >> 10,
> +               swap << (PAGE_SHIFT - 10));
>  }
>
>  unsigned long task_vsize(struct mm_struct *mm)
> Index: mmotm-2.6.32-Nov2/mm/rmap.c
> ===================================================================
> --- mmotm-2.6.32-Nov2.orig/mm/rmap.c
> +++ mmotm-2.6.32-Nov2/mm/rmap.c
> @@ -834,6 +834,7 @@ static int try_to_unmap_one(struct page
>                                spin_unlock(&mmlist_lock);
>                        }
>                        dec_mm_counter(mm, anon_rss);
> +                       inc_mm_counter(mm, swap_usage);
>                } else if (PAGE_MIGRATION) {
>                        /*
>                         * Store the pfn of the page in a special migration
> Index: mmotm-2.6.32-Nov2/kernel/fork.c
> ===================================================================
> --- mmotm-2.6.32-Nov2.orig/kernel/fork.c
> +++ mmotm-2.6.32-Nov2/kernel/fork.c
> @@ -454,6 +454,7 @@ static struct mm_struct * mm_init(struct
>        mm->nr_ptes = 0;
>        set_mm_counter(mm, file_rss, 0);
>        set_mm_counter(mm, anon_rss, 0);
> +       set_mm_counter(mm, swap_usage, 0);
>        spin_lock_init(&mm->page_table_lock);
>        mm->free_area_cache = TASK_UNMAPPED_BASE;
>        mm->cached_hole_size = ~0UL;
>
> --
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> the body to majordomo@kvack.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
>

That's good.
From now on, we can chagne scanning of pte to find swap pte
in smaps_pte_rangem, too. :)

--
Kind regards,
Minchan Kim
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