linux-kernel - Re: [PATCH v2 5/5] f2fs: support age threshold based garbage collection

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Message-ID: <20200831180143.GB3665231@google.com>
Date:   Mon, 31 Aug 2020 11:01:43 -0700
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <yuchao0@...wei.com>
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, chao@...nel.org
Subject: Re: [PATCH v2 5/5] f2fs: support age threshold based garbage
 collection

Hi Chao,

Applied. Thanks.

On 08/31, Chao Yu wrote:
> Hi Jaegeuk,
> 
> I've changed code a bit to fix some bugs, including:
> - gc_idle = 3 (GC_IDLE_AT) description
> - disallow set gc_idle to 3 if atgc is off
> - keep compatibility with checkpoint disabling
> 
> Could you please check and merge below diff?
> 
> From: Chao Yu <yuchao0@...wei.com>
> 
> Signed-off-by: Chao Yu <yuchao0@...wei.com>
> ---
>  Documentation/ABI/testing/sysfs-fs-f2fs |  3 ++-
>  fs/f2fs/gc.c                            | 12 +++++++++++-
>  fs/f2fs/sysfs.c                         | 11 ++++++++---
>  3 files changed, 21 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
> index 7f730c4c8df2..834d0becae6d 100644
> --- a/Documentation/ABI/testing/sysfs-fs-f2fs
> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
> @@ -22,7 +22,8 @@ Contact:	"Namjae Jeon" <namjae.jeon@...sung.com>
>  Description:	Controls the victim selection policy for garbage collection.
>  		Setting gc_idle = 0(default) will disable this option. Setting
>  		gc_idle = 1 will select the Cost Benefit approach & setting
> -		gc_idle = 2 will select the greedy approach.
> +		gc_idle = 2 will select the greedy approach & setting
> +		gc_idle = 3 will select the age-threshold based approach.
> 
>  What:		/sys/fs/f2fs/<disk>/reclaim_segments
>  Date:		October 2013
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index 6413886e52d4..3c0edb8b4cc5 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -388,6 +388,16 @@ static void add_victim_entry(struct f2fs_sb_info *sbi,
>  	unsigned long long mtime = 0;
>  	unsigned int i;
> 
> +	if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED)) {
> +		if (p->gc_mode == GC_AT &&
> +			get_valid_blocks(sbi, segno, true) == 0)
> +			return;
> +
> +		if (p->alloc_mode == AT_SSR &&
> +			get_seg_entry(sbi, segno)->ckpt_valid_blocks == 0)
> +			return;
> +	}
> +
>  	for (i = 0; i < sbi->segs_per_sec; i++)
>  		mtime += get_seg_entry(sbi, start + i)->mtime;
>  	mtime = div_u64(mtime, sbi->segs_per_sec);
> @@ -721,7 +731,7 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>  		/* Don't touch checkpointed data */
>  		if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED) &&
>  					get_ckpt_valid_blocks(sbi, segno) &&
> -					p.alloc_mode != SSR))
> +					p.alloc_mode == LFS))
>  			goto next;
>  		if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
>  			goto next;
> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> index 88ed9969cc86..bacfa9c35e6b 100644
> --- a/fs/f2fs/sysfs.c
> +++ b/fs/f2fs/sysfs.c
> @@ -375,12 +375,17 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
>  		return count;
>  	}
>  	if (!strcmp(a->attr.name, "gc_idle")) {
> -		if (t == GC_IDLE_CB)
> +		if (t == GC_IDLE_CB) {
>  			sbi->gc_mode = GC_IDLE_CB;
> -		else if (t == GC_IDLE_GREEDY)
> +		} else if (t == GC_IDLE_GREEDY) {
>  			sbi->gc_mode = GC_IDLE_GREEDY;
> -		else
> +		} else if (t == GC_IDLE_AT) {
> +			if (!sbi->am.atgc_enabled)
> +				return -EINVAL;
> +			sbi->gc_mode = GC_AT;
> +		} else {
>  			sbi->gc_mode = GC_NORMAL;
> +		}
>  		return count;
>  	}
> 
> -- 
> 2.26.2
>