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    Subject[PATCH 4/5] mm: migrate: Add copy_page_mt into migrate_pages.
    Date
    From: Zi Yan <zi.yan@cs.rutgers.edu>

    From: Zi Yan <ziy@nvidia.com>

    An option is added to move_pages() syscall to use multi-threaded
    page migration.

    Signed-off-by: Zi Yan <ziy@nvidia.com>
    Signed-off-by: Zi Yan <zi.yan@cs.rutgers.edu>
    ---
    include/linux/migrate_mode.h | 1 +
    include/uapi/linux/mempolicy.h | 2 ++
    mm/migrate.c | 27 +++++++++++++++++++--------
    3 files changed, 22 insertions(+), 8 deletions(-)

    diff --git a/include/linux/migrate_mode.h b/include/linux/migrate_mode.h
    index 0e2deb8..c711e2a 100644
    --- a/include/linux/migrate_mode.h
    +++ b/include/linux/migrate_mode.h
    @@ -11,6 +11,7 @@ enum migrate_mode {
    MIGRATE_ASYNC = 1<<0,
    MIGRATE_SYNC_LIGHT = 1<<1,
    MIGRATE_SYNC = 1<<2,
    + MIGRATE_MT = 1<<3,
    };

    #endif /* MIGRATE_MODE_H_INCLUDED */
    diff --git a/include/uapi/linux/mempolicy.h b/include/uapi/linux/mempolicy.h
    index 9cd8b21..5d42dc6 100644
    --- a/include/uapi/linux/mempolicy.h
    +++ b/include/uapi/linux/mempolicy.h
    @@ -54,6 +54,8 @@ enum mpol_rebind_step {
    #define MPOL_MF_LAZY (1<<3) /* Modifies '_MOVE: lazy migrate on fault */
    #define MPOL_MF_INTERNAL (1<<4) /* Internal flags start here */

    +#define MPOL_MF_MOVE_MT (1<<6) /* Use multi-threaded page copy routine */
    +
    #define MPOL_MF_VALID (MPOL_MF_STRICT | \
    MPOL_MF_MOVE | \
    MPOL_MF_MOVE_ALL)
    diff --git a/mm/migrate.c b/mm/migrate.c
    index 4a4cf48..244ece6 100644
    --- a/mm/migrate.c
    +++ b/mm/migrate.c
    @@ -634,6 +634,7 @@ static void copy_huge_page(struct page *dst, struct page *src,
    {
    int i;
    int nr_pages;
    + int rc = -EFAULT;

    if (PageHuge(src)) {
    /* hugetlbfs page */
    @@ -650,10 +651,14 @@ static void copy_huge_page(struct page *dst, struct page *src,
    nr_pages = hpage_nr_pages(src);
    }

    - for (i = 0; i < nr_pages; i++) {
    - cond_resched();
    - copy_highpage(dst + i, src + i);
    - }
    + if (mode & MIGRATE_MT)
    + rc = copy_page_mt(dst, src, nr_pages);
    +
    + if (rc)
    + for (i = 0; i < nr_pages; i++) {
    + cond_resched();
    + copy_highpage(dst + i, src + i);
    + }
    }

    /*
    @@ -1461,11 +1466,16 @@ static struct page *new_page_node(struct page *p, unsigned long private,
    */
    static int do_move_page_to_node_array(struct mm_struct *mm,
    struct page_to_node *pm,
    - int migrate_all)
    + int migrate_all,
    + int migrate_use_mt)
    {
    int err;
    struct page_to_node *pp;
    LIST_HEAD(pagelist);
    + enum migrate_mode mode = MIGRATE_SYNC;
    +
    + if (migrate_use_mt)
    + mode |= MIGRATE_MT;

    down_read(&mm->mmap_sem);

    @@ -1542,7 +1552,7 @@ static int do_move_page_to_node_array(struct mm_struct *mm,
    err = 0;
    if (!list_empty(&pagelist)) {
    err = migrate_pages(&pagelist, new_page_node, NULL,
    - (unsigned long)pm, MIGRATE_SYNC, MR_SYSCALL);
    + (unsigned long)pm, mode, MR_SYSCALL);
    if (err)
    putback_movable_pages(&pagelist);
    }
    @@ -1619,7 +1629,8 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,

    /* Migrate this chunk */
    err = do_move_page_to_node_array(mm, pm,
    - flags & MPOL_MF_MOVE_ALL);
    + flags & MPOL_MF_MOVE_ALL,
    + flags & MPOL_MF_MOVE_MT);
    if (err < 0)
    goto out_pm;

    @@ -1726,7 +1737,7 @@ SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages,
    nodemask_t task_nodes;

    /* Check flags */
    - if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL))
    + if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL|MPOL_MF_MOVE_MT))
    return -EINVAL;

    if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
    --
    2.10.2
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