linux-kernel - Re: [PATCH] mm/madvise: pageout under plugging

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Date:   Fri, 10 Dec 2021 10:02:24 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     Minchan Kim <minchan@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
CC:     Jens Axboe <axboe@...nel.dk>, linux-mm <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Suren Baghdasaryan <surenb@...gle.com>,
        John Dias <joaodias@...gle.com>
Subject: Re: [PATCH] mm/madvise: pageout under plugging

Hi:
On 2021/12/10 8:30, Minchan Kim wrote:
> Likewise shrink_lruvec[1], madvise_pageout could get the benefit
> from per-task block plug.
> 
> [1] 3da367c3e5fc, vmscan: add block plug for page reclaim

It seems there is a block plug in the caller do_madvise already. This one
might not be necessary for madvise.

Many thanks.

> Signed-off-by: Minchan Kim <minchan@...nel.org>
> ---
>  mm/vmscan.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index fb9584641ac7..cf11113f6adb 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2556,6 +2556,7 @@ unsigned long reclaim_pages(struct list_head *page_list)
>  	struct reclaim_stat dummy_stat;
>  	struct page *page;
>  	unsigned int noreclaim_flag;
> +	struct blk_plug plug;
>  	struct scan_control sc = {
>  		.gfp_mask = GFP_KERNEL,
>  		.may_writepage = 1,
> @@ -2564,6 +2565,7 @@ unsigned long reclaim_pages(struct list_head *page_list)
>  		.no_demotion = 1,
>  	};
>  
> +	blk_start_plug(&plug);
>  	noreclaim_flag = memalloc_noreclaim_save();
>  
>  	while (!list_empty(page_list)) {
> @@ -2603,6 +2605,8 @@ unsigned long reclaim_pages(struct list_head *page_list)
>  	}
>  
>  	memalloc_noreclaim_restore(noreclaim_flag);
> +	blk_finish_plug(&plug);
> +
>  
>  	return nr_reclaimed;
>  }
>