On Sat, Jun 11, 2016 at 10:15:59PM +0300, Ebru Akagunduz wrote:
> This patch takes back allocstall comparing when deciding
> whether swapin worthwhile because it does not work,
> if vmevent disabled.
>
> Related commit:
> http://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=2548306628308aa6a326640d345a737bc898941d
>
> Signed-off-by: Ebru Akagunduz <ebru.akagun...@gmail.com>
Suggested-by: Minchan Kim <minc...@kernel.org>
> ---
Cc'ed Minchan Kim.
> mm/khugepaged.c | 31 ++++++++-----------------------
> 1 file changed, 8 insertions(+), 23 deletions(-)
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 0ac63f7..e3d8da7 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -68,7 +68,6 @@ static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
> */
> static unsigned int khugepaged_max_ptes_none __read_mostly;
> static unsigned int khugepaged_max_ptes_swap __read_mostly;
> -static unsigned long allocstall;
>
> static int khugepaged(void *none);
>
> @@ -926,7 +925,6 @@ static void collapse_huge_page(struct mm_struct *mm,
> struct page *new_page;
> spinlock_t *pmd_ptl, *pte_ptl;
> int isolated = 0, result = 0;
> - unsigned long swap, curr_allocstall;
> struct mem_cgroup *memcg;
> unsigned long mmun_start; /* For mmu_notifiers */
> unsigned long mmun_end; /* For mmu_notifiers */
> @@ -955,8 +953,6 @@ static void collapse_huge_page(struct mm_struct *mm,
> goto out_nolock;
> }
>
> - swap = get_mm_counter(mm, MM_SWAPENTS);
> - curr_allocstall = sum_vm_event(ALLOCSTALL);
> down_read(&mm->mmap_sem);
> result = hugepage_vma_revalidate(mm, address);
> if (result) {
> @@ -972,22 +968,15 @@ static void collapse_huge_page(struct mm_struct *mm,
> up_read(&mm->mmap_sem);
> goto out_nolock;
> }
> -
> /*
> - * Don't perform swapin readahead when the system is under pressure,
> - * to avoid unnecessary resource consumption.
> + * __collapse_huge_page_swapin always returns with mmap_sem
> + * locked. If it fails, release mmap_sem and jump directly
> + * out. Continuing to collapse causes inconsistency.
> */
> - if (allocstall == curr_allocstall && swap != 0) {
> - /*
> - * __collapse_huge_page_swapin always returns with mmap_sem
> - * locked. If it fails, release mmap_sem and jump directly
> - * out. Continuing to collapse causes inconsistency.
> - */
> - if (!__collapse_huge_page_swapin(mm, vma, address, pmd)) {
> - mem_cgroup_cancel_charge(new_page, memcg, true);
> - up_read(&mm->mmap_sem);
> - goto out_nolock;
> - }
> + if (!__collapse_huge_page_swapin(mm, vma, address, pmd)) {
> + mem_cgroup_cancel_charge(new_page, memcg, true);
> + up_read(&mm->mmap_sem);
> + goto out_nolock;
> }
>
> up_read(&mm->mmap_sem);
> @@ -1822,7 +1811,6 @@ static void khugepaged_wait_work(void)
> if (!scan_sleep_jiffies)
> return;
>
> - allocstall = sum_vm_event(ALLOCSTALL);
> khugepaged_sleep_expire = jiffies + scan_sleep_jiffies;
> wait_event_freezable_timeout(khugepaged_wait,
> khugepaged_should_wakeup(),
> @@ -1830,10 +1818,8 @@ static void khugepaged_wait_work(void)
> return;
> }
>
> - if (khugepaged_enabled()) {
> - allocstall = sum_vm_event(ALLOCSTALL);
> + if (khugepaged_enabled())
> wait_event_freezable(khugepaged_wait, khugepaged_wait_event());
> - }
> }
>
> static int khugepaged(void *none)
> @@ -1842,7 +1828,6 @@ static int khugepaged(void *none)
>
> set_freezable();
> set_user_nice(current, MAX_NICE);
> - allocstall = sum_vm_event(ALLOCSTALL);
>
> while (!kthread_should_stop()) {
> khugepaged_do_scan();
> --
> 1.9.1
>
