From: Joonsoo Kim <js1304@gmail.com>
To: Hillf Danton <hdanton@sina.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Linux Memory Management List <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>, Hugh Dickins <hughd@google.com>,
Minchan Kim <minchan@kernel.org>,
Vlastimil Babka <vbabka@suse.cz>,
Mel Gorman <mgorman@techsingularity.net>,
kernel-team@lge.com, Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: Re: [PATCH 9/9] mm/swap: count a new anonymous page as a reclaim_state's rotate
Date: Wed, 12 Feb 2020 20:00:13 +0900 [thread overview]
Message-ID: <CAAmzW4MdNndLXe9ExjVuxrQ1GG+GY6M_Tt4wXWS72Q_v3Q8aVA@mail.gmail.com> (raw)
In-Reply-To: <20200212033534.3744-1-hdanton@sina.com>
Hello,
2020년 2월 12일 (수) 오후 12:35, Hillf Danton <hdanton@sina.com>님이 작성:
>
>
> On Mon, 10 Feb 2020 22:20:37 -0800 (PST)
> > From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> >
> > reclaim_stat's rotate is used for controlling the ratio of scanning page
> > between file and anonymous LRU. All new anonymous pages are counted
> > for rotate before the patch, protecting anonymous pages on active LRU, and,
> > it makes that reclaim on anonymous LRU is less happened than file LRU.
> >
> > Now, situation is changed. all new anonymous pages are not added
> > to the active LRU so rotate would be far less than before. It will cause
> > that reclaim on anonymous LRU happens more and it would result in bad
> > effect on some system that is optimized for previous setting.
> >
> > Therefore, this patch counts a new anonymous page as a reclaim_state's
> > rotate. Although it is non-logical to add this count to
> > the reclaim_state's rotate in current algorithm, reducing the regression
> > would be more important.
> >
> > I found this regression on kernel-build test and it is roughly 2~5%
> > performance degradation. With this workaround, performance is completely
> > restored.
> >
> > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> > ---
> > mm/swap.c | 27 ++++++++++++++++++++++++++-
> > 1 file changed, 26 insertions(+), 1 deletion(-)
> >
> > diff --git a/mm/swap.c b/mm/swap.c
> > index 18b2735..c3584af 100644
> > --- a/mm/swap.c
> > +++ b/mm/swap.c
> > @@ -187,6 +187,9 @@ int get_kernel_page(unsigned long start, int write, struct page **pages)
> > }
> > EXPORT_SYMBOL_GPL(get_kernel_page);
> >
> > +static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
> > + void *arg);
> > +
> > static void pagevec_lru_move_fn(struct pagevec *pvec,
> > void (*move_fn)(struct page *page, struct lruvec *lruvec, void *arg),
> > void *arg)
> > @@ -207,6 +210,19 @@ static void pagevec_lru_move_fn(struct pagevec *pvec,
> > spin_lock_irqsave(&pgdat->lru_lock, flags);
> > }
> >
> > + if (move_fn == __pagevec_lru_add_fn) {
> > + struct list_head *entry = &page->lru;
> > + unsigned long next = (unsigned long)entry->next;
> > + unsigned long rotate = next & 2;
> > +
> > + if (rotate) {
> > + VM_BUG_ON(arg);
> > +
> > + next = next & ~2;
> > + entry->next = (struct list_head *)next;
> > + arg = (void *)rotate;
> > + }
> > + }
> > lruvec = mem_cgroup_page_lruvec(page, pgdat);
> > (*move_fn)(page, lruvec, arg);
> > }
> > @@ -475,6 +491,14 @@ void lru_cache_add_inactive_or_unevictable(struct page *page,
> > hpage_nr_pages(page));
> > count_vm_event(UNEVICTABLE_PGMLOCKED);
> > }
> > +
> > + if (PageSwapBacked(page) && evictable) {
> > + struct list_head *entry = &page->lru;
> > + unsigned long next = (unsigned long)entry->next;
> > +
> > + next = next | 2;
> > + entry->next = (struct list_head *)next;
> > + }
> > lru_cache_add(page);
> > }
> >
> > @@ -927,6 +951,7 @@ static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
> > {
> > enum lru_list lru;
> > int was_unevictable = TestClearPageUnevictable(page);
> > + unsigned long rotate = (unsigned long)arg;
> >
> > VM_BUG_ON_PAGE(PageLRU(page), page);
> >
> > @@ -962,7 +987,7 @@ static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
> > if (page_evictable(page)) {
> > lru = page_lru(page);
> > update_page_reclaim_stat(lruvec, page_is_file_cache(page),
> > - PageActive(page));
> > + PageActive(page) | rotate);
>
>
> Is it likely to rotate a page if we know it's not active?
>
> update_page_reclaim_stat(lruvec, page_is_file_cache(page),
> - PageActive(page));
> + PageActive(page) ||
> + !page_is_file_cache(page));
>
My intention is that only newly created anonymous pages contributes
the rotate count.
With your code suggestion, other case for anonymous pages could also contributes
the rotate count since __pagevec_lru_add_fn() is used else where.
Thanks.
next prev parent reply other threads:[~2020-02-12 11:00 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-11 6:19 [PATCH 0/9] workingset protection/detection on the anonymous LRU list js1304
2020-02-11 6:19 ` [PATCH 1/9] mm/vmscan: make active/inactive ratio as 1:1 for anon lru js1304
2020-02-27 2:29 ` [mm/vmscan] dcf33bfdfb: vm-scalability.median 402.4% improvement kernel test robot
2020-02-11 6:19 ` [PATCH 2/9] mm/vmscan: protect the workingset on anonymous LRU js1304
2020-02-11 6:19 ` [PATCH 3/9] mm/workingset: extend the workingset detection for anon LRU js1304
2020-02-14 4:07 ` Joonsoo Kim
2020-02-28 7:42 ` [mm/workingset] 323c95f095: fio.read_bw_MBps 19.5% improvement kernel test robot
2020-02-28 10:03 ` Joonsoo Kim
2020-02-11 6:19 ` [PATCH 4/9] mm/swapcache: support to handle the value in swapcache js1304
2020-02-11 6:19 ` [PATCH 5/9] mm/workingset: use the node counter if memcg is the root memcg js1304
2020-02-11 6:19 ` [PATCH 6/9] mm/workingset: handle the page without memcg js1304
2020-02-11 6:19 ` [PATCH 7/9] mm/swap: implement workingset detection for anonymous LRU js1304
2020-02-11 6:19 ` [PATCH 8/9] mm/vmscan: restore active/inactive ratio " js1304
2020-02-11 6:19 ` [PATCH 9/9] mm/swap: count a new anonymous page as a reclaim_state's rotate js1304
2020-02-12 3:35 ` Hillf Danton
2020-02-12 11:00 ` Joonsoo Kim [this message]
2020-02-14 4:12 ` [PATCH 0/9] workingset protection/detection on the anonymous LRU list Joonsoo Kim
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