Re: [f2fs-dev] [PATCH] f2fs: add gc_boost_gc_multiple sysfs node

[Chao Yu <chao@kernel.org>]

On 2025/6/7 3:20, Daeho Jeong wrote:
> From: Daeho Jeong <daehojeong@google.com>
> 
> Add a sysfs knob to set a multiplier for the background GC migration
> window when F2FS Garbage Collection is boosted.
> 
> Signed-off-by: Daeho Jeong <daehojeong@google.com>
> ---
>   Documentation/ABI/testing/sysfs-fs-f2fs | 8 ++++++++
>   fs/f2fs/gc.c                            | 3 ++-
>   fs/f2fs/gc.h                            | 1 +
>   fs/f2fs/sysfs.c                         | 2 ++
>   4 files changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
> index bf03263b9f46..931c1f63aa2e 100644
> --- a/Documentation/ABI/testing/sysfs-fs-f2fs
> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
> @@ -861,3 +861,11 @@ Description:	This is a read-only entry to show the value of sb.s_encoding_flags,
>   		SB_ENC_STRICT_MODE_FL            0x00000001
>   		SB_ENC_NO_COMPAT_FALLBACK_FL     0x00000002
>   		============================     ==========
> +
> +What:		/sys/fs/f2fs/<disk>/gc_boost_gc_multiple
> +Date:		June 2025
> +Contact:	"Daeho Jeong" <daehojeong@google.com>
> +Description:	Set a multiplier for the background GC migration window when F2FS GC is
> +		boosted.
> +		Default: 5

Do we need to add lower/upper boundary during setting the value via sysfs entry?

Thanks,

> +
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index 3cb5242f4ddf..de7e59bc0906 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -197,6 +197,7 @@ int f2fs_start_gc_thread(struct f2fs_sb_info *sbi)
>   
>   	gc_th->urgent_sleep_time = DEF_GC_THREAD_URGENT_SLEEP_TIME;
>   	gc_th->valid_thresh_ratio = DEF_GC_THREAD_VALID_THRESH_RATIO;
> +	gc_th->boost_gc_multiple = BOOST_GC_MULTIPLE;
>   
>   	if (f2fs_sb_has_blkzoned(sbi)) {
>   		gc_th->min_sleep_time = DEF_GC_THREAD_MIN_SLEEP_TIME_ZONED;
> @@ -1749,7 +1750,7 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>   					!has_enough_free_blocks(sbi,
>   					sbi->gc_thread->boost_zoned_gc_percent))
>   				window_granularity *=
> -					BOOST_GC_MULTIPLE;
> +					sbi->gc_thread->boost_gc_multiple;
>   
>   			end_segno = start_segno + window_granularity;
>   		}
> diff --git a/fs/f2fs/gc.h b/fs/f2fs/gc.h
> index 5c1eaf55e127..efa1968810a0 100644
> --- a/fs/f2fs/gc.h
> +++ b/fs/f2fs/gc.h
> @@ -68,6 +68,7 @@ struct f2fs_gc_kthread {
>   	unsigned int no_zoned_gc_percent;
>   	unsigned int boost_zoned_gc_percent;
>   	unsigned int valid_thresh_ratio;
> +	unsigned int boost_gc_multiple;
>   };
>   
>   struct gc_inode_list {
> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> index 75134d69a0bd..b0270b1c939c 100644
> --- a/fs/f2fs/sysfs.c
> +++ b/fs/f2fs/sysfs.c
> @@ -1050,6 +1050,7 @@ GC_THREAD_RW_ATTR(gc_no_gc_sleep_time, no_gc_sleep_time);
>   GC_THREAD_RW_ATTR(gc_no_zoned_gc_percent, no_zoned_gc_percent);
>   GC_THREAD_RW_ATTR(gc_boost_zoned_gc_percent, boost_zoned_gc_percent);
>   GC_THREAD_RW_ATTR(gc_valid_thresh_ratio, valid_thresh_ratio);
> +GC_THREAD_RW_ATTR(gc_boost_gc_multiple, boost_gc_multiple);
>   
>   /* SM_INFO ATTR */
>   SM_INFO_RW_ATTR(reclaim_segments, rec_prefree_segments);
> @@ -1220,6 +1221,7 @@ static struct attribute *f2fs_attrs[] = {
>   	ATTR_LIST(gc_no_zoned_gc_percent),
>   	ATTR_LIST(gc_boost_zoned_gc_percent),
>   	ATTR_LIST(gc_valid_thresh_ratio),
> +	ATTR_LIST(gc_boost_gc_multiple),
>   	ATTR_LIST(gc_idle),
>   	ATTR_LIST(gc_urgent),
>   	ATTR_LIST(reclaim_segments),