linux-kernel - Re: [PATCH v2 1/3] mm, lru_gen: batch update counters on againg

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Message-ID: <CAMgjq7CSDJHf=BWLThPbaRRW104swbGwwis1mJkTj+xbhAn5nw@mail.gmail.com>
Date: Fri, 12 Jan 2024 02:37:54 +0800
From: Kairui Song <ryncsn@...il.com>
To: linux-mm@...ck.org
Cc: Andrew Morton <akpm@...ux-foundation.org>, Yu Zhao <yuzhao@...gle.com>, 
	Chris Li <chrisl@...nel.org>, Matthew Wilcox <willy@...radead.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/3] mm, lru_gen: batch update counters on againg

Kairui Song <ryncsn@...il.com> 于2024年1月12日周五 02:33写道：
>
> From: Kairui Song <kasong@...cent.com>
>
> When lru_gen is aging, it will update mm counters page by page,
> which causes a higher overhead if age happens frequently or there
> are a lot of pages in one generation getting moved.
> Optimize this by doing the counter update in batch.
>
> Although most __mod_*_state has its own caches the overhead
> is still observable.
>
> Tested in a 4G memcg on a EPYC 7K62 with:
>
>   memcached -u nobody -m 16384 -s /tmp/memcached.socket \
>     -a 0766 -t 16 -B binary &
>
>   memtier_benchmark -S /tmp/memcached.socket \
>     -P memcache_binary -n allkeys \
>     --key-minimum=1 --key-maximum=16000000 -d 1024 \
>     --ratio=1:0 --key-pattern=P:P -c 2 -t 16 --pipeline 8 -x 6
>
> Average result of 18 test runs:
>
> Before: 44017.78 Ops/sec
> After:  44687.08 Ops/sec (+1.5%)
>
> Signed-off-by: Kairui Song <kasong@...cent.com>
> ---
>  mm/vmscan.c | 64 +++++++++++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 55 insertions(+), 9 deletions(-)
>

My apology for being careless again here... the title here should be:
mm, lru_gen: batch update counters on aging