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Date: Fri, 10 Feb 2017 09:30:09 -0800
From: Shaohua Li <shli@...com>
To: Minchan Kim <minchan@...nel.org>
CC: <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
<Kernel-team@...com>, <danielmicay@...il.com>, <mhocko@...e.com>,
<hughd@...gle.com>, <hannes@...xchg.org>, <riel@...hat.com>,
<mgorman@...hsingularity.net>, <akpm@...ux-foundation.org>
Subject: Re: [PATCH V2 2/7] mm: move MADV_FREE pages into LRU_INACTIVE_FILE
list
On Fri, Feb 10, 2017 at 03:50:22PM +0900, Minchan Kim wrote:
> Hi Shaohua,
Thanks for your time!
> On Fri, Feb 03, 2017 at 03:33:18PM -0800, Shaohua Li wrote:
> > Userspace indicates MADV_FREE pages could be freed without pageout, so
> > it pretty much likes used once file pages. For such pages, we'd like to
> > reclaim them once there is memory pressure. Also it might be unfair
> > reclaiming MADV_FREE pages always before used once file pages and we
> > definitively want to reclaim the pages before other anonymous and file
> > pages.
> >
> > To speed up MADV_FREE pages reclaim, we put the pages into
> > LRU_INACTIVE_FILE list. The rationale is LRU_INACTIVE_FILE list is tiny
> > nowadays and should be full of used once file pages. Reclaiming
> > MADV_FREE pages will not have much interfere of anonymous and active
> > file pages. And the inactive file pages and MADV_FREE pages will be
> > reclaimed according to their age, so we don't reclaim too many MADV_FREE
> > pages too. Putting the MADV_FREE pages into LRU_INACTIVE_FILE_LIST also
> > means we can reclaim the pages without swap support. This idea is
> > suggested by Johannes.
> >
> > We also clear the pages SwapBacked flag to indicate they are MADV_FREE
> > pages.
>
> I think this patch should be merged with 3/7. Otherwise, MADV_FREE will
> be broken during the bisect.
Maybe I should move the patch 3 ahead, then we won't break bisect and still
make the patches clear.
> > Cc: Michal Hocko <mhocko@...e.com>
> > Cc: Minchan Kim <minchan@...nel.org>
> > Cc: Hugh Dickins <hughd@...gle.com>
> > Cc: Johannes Weiner <hannes@...xchg.org>
> > Cc: Rik van Riel <riel@...hat.com>
> > Cc: Mel Gorman <mgorman@...hsingularity.net>
> > Cc: Andrew Morton <akpm@...ux-foundation.org>
> > Signed-off-by: Shaohua Li <shli@...com>
> > ---
> > include/linux/mm_inline.h | 5 +++++
> > include/linux/swap.h | 2 +-
> > include/linux/vm_event_item.h | 2 +-
> > mm/huge_memory.c | 5 ++---
> > mm/madvise.c | 3 +--
> > mm/swap.c | 50 ++++++++++++++++++++++++-------------------
> > mm/vmstat.c | 1 +
> > 7 files changed, 39 insertions(+), 29 deletions(-)
> >
> > diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
> > index e030a68..fdded06 100644
> > --- a/include/linux/mm_inline.h
> > +++ b/include/linux/mm_inline.h
> > @@ -22,6 +22,11 @@ static inline int page_is_file_cache(struct page *page)
> > return !PageSwapBacked(page);
> > }
> >
> > +static inline bool page_is_lazyfree(struct page *page)
> > +{
> > + return PageAnon(page) && !PageSwapBacked(page);
> > +}
> > +
>
> trivial:
>
> How about using PageLazyFree for consistency with other PageXXX?
> As well, use SetPageLazyFree/ClearPageLazyFree rather than using
> raw {Set,Clear}PageSwapBacked.
So SetPageLazyFree == ClearPageSwapBacked, that would be weird. I personally
prefer directly using {Set, Clear}PageSwapBacked, because reader can
immediately know what's happening. If using the PageLazyFree, people always
need to refer the code and check the relationship between PageLazyFree and
PageSwapBacked.
> > static __always_inline void __update_lru_size(struct lruvec *lruvec,
> > enum lru_list lru, enum zone_type zid,
> > int nr_pages)
> > diff --git a/include/linux/swap.h b/include/linux/swap.h
> > index 45e91dd..486494e 100644
> > --- a/include/linux/swap.h
> > +++ b/include/linux/swap.h
> > @@ -279,7 +279,7 @@ extern void lru_add_drain_cpu(int cpu);
> > extern void lru_add_drain_all(void);
> > extern void rotate_reclaimable_page(struct page *page);
> > extern void deactivate_file_page(struct page *page);
> > -extern void deactivate_page(struct page *page);
> > +extern void mark_page_lazyfree(struct page *page);
>
> trivial:
>
> How about "deactivate_lazyfree_page"? IMO, it would show intention
> clear that move the lazy free page to inactive list.
>
> It's just matter of preference so I'm not strong against.
Yes, I thought about the name a little bit. Don't think we should use
deactivate, because it sounds that only works for active page, while the
function works for both active/inactive pages. I'm open to any suggestions.
> > extern void swap_setup(void);
> >
> > extern void add_page_to_unevictable_list(struct page *page);
> > diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
> > index 6aa1b6c..94e58da 100644
> > --- a/include/linux/vm_event_item.h
> > +++ b/include/linux/vm_event_item.h
> > @@ -25,7 +25,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
> > FOR_ALL_ZONES(PGALLOC),
> > FOR_ALL_ZONES(ALLOCSTALL),
> > FOR_ALL_ZONES(PGSCAN_SKIP),
> > - PGFREE, PGACTIVATE, PGDEACTIVATE,
> > + PGFREE, PGACTIVATE, PGDEACTIVATE, PGLAZYFREE,
> > PGFAULT, PGMAJFAULT,
> > PGLAZYFREED,
> > PGREFILL,
> > diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> > index ecf569d..ddb9a94 100644
> > --- a/mm/huge_memory.c
> > +++ b/mm/huge_memory.c
> > @@ -1391,9 +1391,6 @@ bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
> > ClearPageDirty(page);
> > unlock_page(page);
> >
> > - if (PageActive(page))
> > - deactivate_page(page);
> > -
> > if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
> > orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
> > tlb->fullmm);
> > @@ -1404,6 +1401,8 @@ bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
> > set_pmd_at(mm, addr, pmd, orig_pmd);
> > tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
> > }
> > +
> > + mark_page_lazyfree(page);
> > ret = true;
> > out:
> > spin_unlock(ptl);
> > diff --git a/mm/madvise.c b/mm/madvise.c
> > index c867d88..c24549e 100644
> > --- a/mm/madvise.c
> > +++ b/mm/madvise.c
> > @@ -378,10 +378,9 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
> > ptent = pte_mkclean(ptent);
> > ptent = pte_wrprotect(ptent);
> > set_pte_at(mm, addr, pte, ptent);
> > - if (PageActive(page))
> > - deactivate_page(page);
> > tlb_remove_tlb_entry(tlb, pte, addr);
> > }
> > + mark_page_lazyfree(page);
> > }
> > out:
> > if (nr_swap) {
> > diff --git a/mm/swap.c b/mm/swap.c
> > index c4910f1..69a7e9d 100644
> > --- a/mm/swap.c
> > +++ b/mm/swap.c
> > @@ -46,7 +46,7 @@ int page_cluster;
> > static DEFINE_PER_CPU(struct pagevec, lru_add_pvec);
> > static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
> > static DEFINE_PER_CPU(struct pagevec, lru_deactivate_file_pvecs);
> > -static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs);
> > +static DEFINE_PER_CPU(struct pagevec, lru_lazyfree_pvecs);
> > #ifdef CONFIG_SMP
> > static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
> > #endif
> > @@ -268,6 +268,11 @@ static void __activate_page(struct page *page, struct lruvec *lruvec,
> > int lru = page_lru_base_type(page);
> >
> > del_page_from_lru_list(page, lruvec, lru);
> > + if (page_is_lazyfree(page)) {
> > + SetPageSwapBacked(page);
> > + file = 0;
>
> I don't see why you set file with 0. Could you explain the rationale?
We are moving the page back to active anonymous list, so I'd like to charge the
recent_scanned and recent_rotated to anonymous.
Thanks,
Shaohua
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