From: Alex Shi <alex.shi@linux.alibaba.com>
To: Alexander Duyck <alexander.duyck@gmail.com>
Cc: yang.shi@linux.alibaba.com, lkp@intel.com, rong.a.chen@intel.com,
khlebnikov@yandex-team.ru, kirill@shutemov.name,
hughd@google.com, linux-kernel@vger.kernel.org,
daniel.m.jordan@oracle.com, linux-mm@kvack.org,
shakeelb@google.com, willy@infradead.org, hannes@cmpxchg.org,
tj@kernel.org, cgroups@vger.kernel.org,
akpm@linux-foundation.org, richard.weiyang@gmail.com,
mgorman@techsingularity.net, iamjoonsoo.kim@lge.com
Subject: Re: [RFC PATCH 2/3] mm: Drop use of test_and_set_skip in favor of just setting skip
Date: Tue, 18 Aug 2020 14:50:25 +0800 [thread overview]
Message-ID: <176fae1b-b95b-51c3-d8cc-4380f0972666@linux.alibaba.com> (raw)
In-Reply-To: <20200813040232.13054.82417.stgit@localhost.localdomain>
在 2020/8/13 下午12:02, Alexander Duyck 写道:
> From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
>
> The only user of test_and_set_skip was isolate_migratepages_block and it
> was using it after a call that was testing and clearing the LRU flag. As
> such it really didn't need to be behind the LRU lock anymore as it wasn't
> really fulfilling its purpose.
>
> With that being the case we can simply drop the bit and instead directly
> just call the set_pageblock_skip function if the page we are working on is
> the valid_page at the start of the pageblock. It shouldn't be possible for
> us to encounter the bit being set since we obtained the LRU flag for the
> first page in the pageblock which means we would have exclusive access to
> setting the skip bit. As such we don't need to worry about the abort case
> since no other thread will be able to call what used to be
> test_and_set_skip.
>
> Since we have dropped the late abort case we can drop the code that was
> clearing the LRU flag and calling page_put since the abort case will now
> not be holding a reference to a page.
>
> Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
After my false sharing remove on pageblock_flags, this patch looks fine with
a minor change
> ---
> mm/compaction.c | 50 +++++++-------------------------------------------
> 1 file changed, 7 insertions(+), 43 deletions(-)
>
> diff --git a/mm/compaction.c b/mm/compaction.c
> index 5021a18ef722..c1e9918f9dd4 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -399,29 +399,6 @@ void reset_isolation_suitable(pg_data_t *pgdat)
> }
> }
>
> -/*
> - * Sets the pageblock skip bit if it was clear. Note that this is a hint as
> - * locks are not required for read/writers. Returns true if it was already set.
> - */
> -static bool test_and_set_skip(struct compact_control *cc, struct page *page,
> - unsigned long pfn)
> -{
> - bool skip;
> -
> - /* Do no update if skip hint is being ignored */
> - if (cc->ignore_skip_hint)
> - return false;
> -
> - if (!IS_ALIGNED(pfn, pageblock_nr_pages))
> - return false;
> -
> - skip = get_pageblock_skip(page);
> - if (!skip && !cc->no_set_skip_hint)
> - skip = !set_pageblock_skip(page);
> -
> - return skip;
> -}
> -
> static void update_cached_migrate(struct compact_control *cc, unsigned long pfn)
> {
> struct zone *zone = cc->zone;
> @@ -480,12 +457,6 @@ static inline void update_pageblock_skip(struct compact_control *cc,
> static void update_cached_migrate(struct compact_control *cc, unsigned long pfn)
> {
> }
> -
> -static bool test_and_set_skip(struct compact_control *cc, struct page *page,
> - unsigned long pfn)
> -{
> - return false;
> -}
> #endif /* CONFIG_COMPACTION */
>
> /*
> @@ -895,7 +866,6 @@ static bool too_many_isolated(pg_data_t *pgdat)
> if (!valid_page && IS_ALIGNED(low_pfn, pageblock_nr_pages)) {
> if (!cc->ignore_skip_hint && get_pageblock_skip(page)) {
> low_pfn = end_pfn;
> - page = NULL;
> goto isolate_abort;
> }
> valid_page = page;
> @@ -991,6 +961,13 @@ static bool too_many_isolated(pg_data_t *pgdat)
> if (!TestClearPageLRU(page))
> goto isolate_fail_put;
>
> + /* Indicate that we want exclusive access to this pageblock */
> + if (page == valid_page) {
> + skip_updated = true;
> + if (!cc->ignore_skip_hint)
if (!cc->ignore_skip_hint && !cc->no_set_skip_hint)
no_set_skip_hint needs to add here.
Thanks
Alex
> + set_pageblock_skip(page);
> + }
> +
> /* If we already hold the lock, we can skip some rechecking */
> if (!lruvec || !lruvec_holds_page_lru_lock(page, lruvec)) {
> if (lruvec)
> @@ -1002,13 +979,6 @@ static bool too_many_isolated(pg_data_t *pgdat)
>
> lruvec_memcg_debug(lruvec, page);
>
> - /* Try get exclusive access under lock */
> - if (!skip_updated) {
> - skip_updated = true;
> - if (test_and_set_skip(cc, page, low_pfn))
> - goto isolate_abort;
> - }
> -
> /*
> * Page become compound since the non-locked check,
> * and it's on LRU. It can only be a THP so the order
> @@ -1094,15 +1064,9 @@ static bool too_many_isolated(pg_data_t *pgdat)
> if (unlikely(low_pfn > end_pfn))
> low_pfn = end_pfn;
>
> - page = NULL;
> -
> isolate_abort:
> if (lruvec)
> unlock_page_lruvec_irqrestore(lruvec, flags);
> - if (page) {
> - SetPageLRU(page);
> - put_page(page);
> - }
>
> /*
> * Updated the cached scanner pfn once the pageblock has been scanned
>
next prev parent reply other threads:[~2020-08-18 6:51 UTC|newest]
Thread overview: 102+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-25 12:59 [PATCH v17 00/21] per memcg lru lock Alex Shi
2020-07-25 12:59 ` [PATCH v17 01/21] mm/vmscan: remove unnecessary lruvec adding Alex Shi
2020-08-06 3:47 ` Alex Shi
2020-07-25 12:59 ` [PATCH v17 02/21] mm/page_idle: no unlikely double check for idle page counting Alex Shi
2020-07-25 12:59 ` [PATCH v17 03/21] mm/compaction: correct the comments of compact_defer_shift Alex Shi
2020-07-27 17:29 ` Alexander Duyck
2020-07-28 11:59 ` Alex Shi
2020-07-28 14:17 ` Alexander Duyck
2020-07-25 12:59 ` [PATCH v17 04/21] mm/compaction: rename compact_deferred as compact_should_defer Alex Shi
2020-07-25 12:59 ` [PATCH v17 05/21] mm/thp: move lru_add_page_tail func to huge_memory.c Alex Shi
2020-07-25 12:59 ` [PATCH v17 06/21] mm/thp: clean up lru_add_page_tail Alex Shi
2020-07-25 12:59 ` [PATCH v17 07/21] mm/thp: remove code path which never got into Alex Shi
2020-07-25 12:59 ` [PATCH v17 08/21] mm/thp: narrow lru locking Alex Shi
2020-07-25 12:59 ` [PATCH v17 09/21] mm/memcg: add debug checking in lock_page_memcg Alex Shi
2020-07-25 12:59 ` [PATCH v17 10/21] mm/swap: fold vm event PGROTATED into pagevec_move_tail_fn Alex Shi
2020-07-25 12:59 ` [PATCH v17 11/21] mm/lru: move lru_lock holding in func lru_note_cost_page Alex Shi
2020-08-05 21:18 ` Alexander Duyck
2020-07-25 12:59 ` [PATCH v17 12/21] mm/lru: move lock into lru_note_cost Alex Shi
2020-07-25 12:59 ` [PATCH v17 13/21] mm/lru: introduce TestClearPageLRU Alex Shi
2020-07-29 3:53 ` Alex Shi
2020-08-05 22:43 ` Alexander Duyck
2020-08-06 1:54 ` Alex Shi
2020-08-06 14:41 ` Alexander Duyck
2020-07-25 12:59 ` [PATCH v17 14/21] mm/compaction: do page isolation first in compaction Alex Shi
2020-08-04 21:35 ` Alexander Duyck
2020-08-06 18:38 ` Alexander Duyck
2020-08-07 3:24 ` Alex Shi
2020-08-07 14:51 ` Alexander Duyck
2020-08-10 13:10 ` Alex Shi
2020-08-10 14:41 ` Alexander Duyck
2020-08-11 8:22 ` Alex Shi
2020-08-11 14:47 ` Alexander Duyck
2020-08-12 11:43 ` Alex Shi
2020-08-12 12:16 ` Alex Shi
2020-08-12 16:51 ` Alexander Duyck
2020-08-13 1:46 ` Alex Shi
2020-08-13 2:17 ` Alexander Duyck
2020-08-13 3:52 ` Alex Shi
2020-08-13 4:02 ` [RFC PATCH 0/3] " Alexander Duyck
2020-08-13 4:02 ` [RFC PATCH 1/3] mm: Drop locked from isolate_migratepages_block Alexander Duyck
2020-08-13 6:56 ` Alex Shi
2020-08-13 14:32 ` Alexander Duyck
2020-08-14 7:25 ` Alex Shi
2020-08-13 7:44 ` Alex Shi
2020-08-13 14:26 ` Alexander Duyck
2020-08-13 4:02 ` [RFC PATCH 2/3] mm: Drop use of test_and_set_skip in favor of just setting skip Alexander Duyck
2020-08-14 7:19 ` Alex Shi
2020-08-14 14:24 ` Alexander Duyck
2020-08-14 21:15 ` Alexander Duyck
2020-08-15 9:49 ` Alex Shi
2020-08-17 15:38 ` Alexander Duyck
2020-08-18 6:50 ` Alex Shi [this message]
2020-08-13 4:02 ` [RFC PATCH 3/3] mm: Identify compound pages sooner in isolate_migratepages_block Alexander Duyck
2020-08-14 7:20 ` Alex Shi
2020-08-17 22:58 ` [PATCH v17 14/21] mm/compaction: do page isolation first in compaction Alexander Duyck
2020-07-25 12:59 ` [PATCH v17 15/21] mm/thp: add tail pages into lru anyway in split_huge_page() Alex Shi
2020-07-25 12:59 ` [PATCH v17 16/21] mm/swap: serialize memcg changes in pagevec_lru_move_fn Alex Shi
2020-07-25 12:59 ` [PATCH v17 17/21] mm/lru: replace pgdat lru_lock with lruvec lock Alex Shi
2020-07-27 23:34 ` Alexander Duyck
2020-07-28 7:15 ` Alex Shi
2020-07-28 11:19 ` Alex Shi
2020-07-28 14:54 ` Alexander Duyck
2020-07-29 1:00 ` Alex Shi
2020-07-29 1:27 ` Alexander Duyck
2020-07-29 2:27 ` Alex Shi
2020-07-28 15:39 ` Alex Shi
2020-07-28 15:55 ` Alexander Duyck
2020-07-29 0:48 ` Alex Shi
2020-07-29 3:54 ` Alex Shi
2020-08-06 7:41 ` Alex Shi
2020-07-25 12:59 ` [PATCH v17 18/21] mm/lru: introduce the relock_page_lruvec function Alex Shi
2020-07-29 17:52 ` Alexander Duyck
2020-07-30 6:08 ` Alex Shi
2020-07-31 14:20 ` Alexander Duyck
2020-07-31 21:14 ` [PATCH RFC] mm: Add function for testing if the current lruvec lock is valid alexander.h.duyck
2020-07-31 23:54 ` Alex Shi
2020-08-02 18:20 ` Alexander Duyck
2020-08-04 6:13 ` Alex Shi
2020-07-25 12:59 ` [PATCH v17 19/21] mm/vmscan: use relock for move_pages_to_lru Alex Shi
2020-08-03 22:49 ` Alexander Duyck
2020-08-04 6:23 ` Alex Shi
2020-07-25 12:59 ` [PATCH v17 20/21] mm/pgdat: remove pgdat lru_lock Alex Shi
2020-08-03 22:42 ` Alexander Duyck
2020-08-03 22:45 ` Alexander Duyck
2020-08-04 6:22 ` Alex Shi
2020-07-25 12:59 ` [PATCH v17 21/21] mm/lru: revise the comments of lru_lock Alex Shi
2020-08-03 22:37 ` Alexander Duyck
2020-08-04 10:04 ` Alex Shi
2020-08-04 14:29 ` Alexander Duyck
2020-08-06 1:39 ` Alex Shi
2020-08-06 16:27 ` Alexander Duyck
2020-07-27 5:40 ` [PATCH v17 00/21] per memcg lru lock Alex Shi
2020-07-29 14:49 ` Alex Shi
2020-07-29 18:06 ` Hugh Dickins
2020-07-30 2:16 ` Alex Shi
2020-08-03 15:07 ` Michal Hocko
2020-08-04 6:14 ` Alex Shi
2020-07-31 21:31 ` Alexander Duyck
2020-08-04 8:36 ` Alex Shi
2020-08-04 8:36 ` Alex Shi
2020-08-04 8:37 ` Alex Shi
2020-08-04 8:37 ` Alex Shi
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