From: Yu Zhao <yuzhao@google.com>
To: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>, Michal Hocko <mhocko@suse.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH next] mm/swap.c: reduce lock contention in lru_cache_add
Date: Thu, 26 Nov 2020 00:24:02 -0700 [thread overview]
Message-ID: <20201126072402.GA1047005@google.com> (raw)
In-Reply-To: <ed19e3f7-33cb-20ae-537e-a7ada2036895@linux.alibaba.com>
On Thu, Nov 26, 2020 at 02:39:03PM +0800, Alex Shi wrote:
>
>
> 在 2020/11/26 下午12:52, Yu Zhao 写道:
> >> */
> >> void __pagevec_lru_add(struct pagevec *pvec)
> >> {
> >> - int i;
> >> - struct lruvec *lruvec = NULL;
> >> + int i, nr_lruvec;
> >> unsigned long flags = 0;
> >> + struct page *page;
> >> + struct lruvecs lruvecs;
> >>
> >> - for (i = 0; i < pagevec_count(pvec); i++) {
> >> - struct page *page = pvec->pages[i];
> >> + nr_lruvec = sort_page_lruvec(&lruvecs, pvec);
> > Simply looping pvec multiple times (15 at most) for different lruvecs
> > would be better because 1) it requires no extra data structures and
> > therefore has better cache locality (theoretically faster) 2) it only
> > loops once when !CONFIG_MEMCG and !CONFIG_NUMA and therefore has no
> > impact on Android and Chrome OS.
> >
>
> With multiple memcgs, it do help a lot, I had gotten 30% grain on readtwice
> case. but yes, w/o MEMCG and NUMA, it's good to keep old behavior. So
> would you like has a proposal for this?
Oh, no, I'm not against your idea. I was saying it doesn't seem
necessary to sort -- a nested loop would just do the job given
pagevec is small.
diff --git a/mm/swap.c b/mm/swap.c
index cb3794e13b48..1d238edc2907 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -996,15 +996,26 @@ static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec)
*/
void __pagevec_lru_add(struct pagevec *pvec)
{
- int i;
+ int i, j;
struct lruvec *lruvec = NULL;
unsigned long flags = 0;
for (i = 0; i < pagevec_count(pvec); i++) {
struct page *page = pvec->pages[i];
+ if (!page)
+ continue;
+
lruvec = relock_page_lruvec_irqsave(page, lruvec, &flags);
- __pagevec_lru_add_fn(page, lruvec);
+
+ for (j = i; j < pagevec_count(pvec); j++) {
+ if (page_to_nid(pvec->pages[j]) != page_to_nid(page) ||
+ page_memcg(pvec->pages[j]) != page_memcg(page))
+ continue;
+
+ __pagevec_lru_add_fn(pvec->pages[j], lruvec);
+ pvec->pages[j] = NULL;
+ }
}
if (lruvec)
unlock_page_lruvec_irqrestore(lruvec, flags);
next prev parent reply other threads:[~2020-11-26 7:24 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-20 8:27 [PATCH next] mm/swap.c: reduce lock contention in lru_cache_add Alex Shi
2020-11-20 23:19 ` Andrew Morton
2020-11-23 4:46 ` Alex Shi
2020-11-25 15:38 ` Vlastimil Babka
2020-11-26 3:12 ` Alex Shi
2020-11-26 11:05 ` Vlastimil Babka
2020-11-26 4:52 ` Yu Zhao
2020-11-26 6:39 ` Alex Shi
2020-11-26 7:24 ` Yu Zhao [this message]
2020-11-26 8:09 ` Alex Shi
2020-11-26 11:22 ` Vlastimil Babka
2020-11-26 15:44 ` Vlastimil Babka
2020-11-26 15:55 ` Matthew Wilcox
2020-11-27 3:14 ` Alex Shi
2020-12-01 8:02 ` [PATCH 1/3] mm/swap.c: pre-sort pages in pagevec for pagevec_lru_move_fn Alex Shi
2020-12-01 8:02 ` [PATCH 2/3] mm/swap.c: bail out early for no memcg and no numa Alex Shi
2020-12-01 8:02 ` [PATCH 3/3] mm/swap.c: extend the usage to pagevec_lru_add Alex Shi
2020-12-01 8:10 ` [PATCH 1/3] mm/swap.c: pre-sort pages in pagevec for pagevec_lru_move_fn Michal Hocko
2020-12-01 8:20 ` Alex Shi
2020-12-25 9:59 ` [RFC PATCH 0/4] pre sort pages on lruvec in pagevec Alex Shi
2020-12-25 9:59 ` [RFC PATCH 1/4] mm/swap.c: pre-sort pages in pagevec for pagevec_lru_move_fn Alex Shi
2020-12-25 9:59 ` [RFC PATCH 2/4] mm/swap.c: bail out early for no memcg and no numa Alex Shi
2020-12-25 9:59 ` [RFC PATCH 3/4] mm/swap.c: extend the usage to pagevec_lru_add Alex Shi
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