On 11/22/2016 09:55 PM, Zi Yan wrote:
> From: Zi Yan <zi.yan@xxxxxxxxxxxxxx>
>
> From: Zi Yan <ziy@xxxxxxxxxx>
>
> An option is added to move_pages() syscall to use multi-threaded
> page migration.
>
> Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
> Signed-off-by: Zi Yan <zi.yan@xxxxxxxxxxxxxx>
> ---
> 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,
MIGRATE_MTHREAD should be better.
> };
>
> #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 */
> +
s/MPOL_MF_MOVE_MT/MPOL_MF_MOVE_MTHREAD/
> #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);
> + }
> }
So this is the case where MIGRATE_MT is mentioned or when it fails.
A small documentation above the code block should be good.
>
> /*
> @@ -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;
Wondering if do_move_pages_to_node_array() is the only place which
needs to be changed to accommodate this.
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