linux-kernel - Re: [PATCH] f2fs: init discard policy after thread wakeup

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Date:   Wed, 23 Nov 2022 23:36:39 +0800
From:   Chao Yu <chao@...nel.org>
To:     Yangtao Li <frank.li@...o.com>, jaegeuk@...nel.org
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] f2fs: init discard policy after thread wakeup

On 2022/11/18 11:46, Yangtao Li wrote:
> Under the current logic, after the discard thread wakes up, it will not
> run according to the expected policy, but will use the expected policy
> before sleep. Move the strategy selection to after the thread wakes up,
> so that the running state of the thread meets expectations.
> 
> Signed-off-by: Yangtao Li <frank.li@...o.com>
> ---
>   fs/f2fs/segment.c | 20 +++++++++-----------
>   1 file changed, 9 insertions(+), 11 deletions(-)
> 
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 8b0b76550578..609e90aa80c2 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -1685,6 +1685,11 @@ static int issue_discard_thread(void *data)
>   	set_freezable();
>   
>   	do {

		if (!atomic_read(&dcc->discard_cmd_cnt))
		       wait_ms = dpolicy.max_interval;

Thanks,

> +		wait_event_interruptible_timeout(*q,
> +				kthread_should_stop() || freezing(current) ||
> +				dcc->discard_wake,
> +				msecs_to_jiffies(wait_ms));
> +
>   		if (sbi->gc_mode == GC_URGENT_HIGH ||
>   			!f2fs_available_free_memory(sbi, DISCARD_CACHE))
>   			__init_discard_policy(sbi, &dpolicy, DPOLICY_FORCE, 1);
> @@ -1692,14 +1697,6 @@ static int issue_discard_thread(void *data)
>   			__init_discard_policy(sbi, &dpolicy, DPOLICY_BG,
>   						dcc->discard_granularity);
>   
> -		if (!atomic_read(&dcc->discard_cmd_cnt))
> -		       wait_ms = dpolicy.max_interval;
> -
> -		wait_event_interruptible_timeout(*q,
> -				kthread_should_stop() || freezing(current) ||
> -				dcc->discard_wake,
> -				msecs_to_jiffies(wait_ms));
> -
>   		if (dcc->discard_wake)
>   			dcc->discard_wake = 0;
>   
> @@ -1713,12 +1710,11 @@ static int issue_discard_thread(void *data)
>   			continue;
>   		if (kthread_should_stop())
>   			return 0;
> -		if (is_sbi_flag_set(sbi, SBI_NEED_FSCK)) {
> +		if (is_sbi_flag_set(sbi, SBI_NEED_FSCK) ||
> +			!atomic_read(&dcc->discard_cmd_cnt)) {
>   			wait_ms = dpolicy.max_interval;
>   			continue;
>   		}
> -		if (!atomic_read(&dcc->discard_cmd_cnt))
> -			continue;
>   
>   		sb_start_intwrite(sbi->sb);
>   
> @@ -1733,6 +1729,8 @@ static int issue_discard_thread(void *data)
>   		} else {
>   			wait_ms = dpolicy.max_interval;
>   		}
> +		if (!atomic_read(&dcc->discard_cmd_cnt))
> +			wait_ms = dpolicy.max_interval;
>   
>   		sb_end_intwrite(sbi->sb);
>