Re: [f2fs-dev] [PATCH v4] f2fs:Add write priority option based on zone UFS

[Chao Yu <chao@kernel.org>]

On 2024/7/10 11:06, Liao Yuanhong wrote:
> Currently, we are using a mix of traditional UFS and zone UFS to support
> some functionalities that cannot be achieved on zone UFS alone. However,
> there are some issues with this approach. There exists a significant
> performance difference between traditional UFS and zone UFS. Under normal
> usage, we prioritize writes to zone UFS. However, in critical conditions
> (such as when the entire UFS is almost full), we cannot determine whether
> data will be written to traditional UFS or zone UFS. This can lead to
> significant performance fluctuations, which is not conducive to
> development and testing. To address this, we have added an option
> zlu_io_enable under sys with the following three modes:
> 1) zlu_io_enable == 0:Normal mode, prioritize writing to zone UFS;
> 2) zlu_io_enable == 1:Zone UFS only mode, only allow writing to zone UFS;
> 3) zlu_io_enable == 2:Traditional UFS priority mode, prioritize writing to
> traditional UFS.
> 
> Signed-off-by: Liao Yuanhong <liaoyuanhong@vivo.com>
> Signed-off-by: Wu Bo <bo.wu@vivo.com>
> ---
> v4:
> 	-Change some constant's name.
> ---
> v3:
> 	-Delete excess comments,
> 	-Use enum instead of define,
> 	-Modify some judgment criteria to make them more reasonable.
> ---
> v2:
> 	-Change name to blkzone_alloc_policy,
> 	-Update manual of f2fs sysfs entry,
> 	-Use macro instead of magic number,
> 	-Initialize it w/ default policy in f2fs_scan_devices,
> 	-Add validation check,
> 	-Merged the ifdef PROFIG-BLK-DEV_ZONED area.
> ---
>   Documentation/ABI/testing/sysfs-fs-f2fs | 14 ++++++++++++++
>   fs/f2fs/f2fs.h                          |  8 ++++++++
>   fs/f2fs/segment.c                       | 25 ++++++++++++++++++++++++-
>   fs/f2fs/super.c                         |  1 +
>   fs/f2fs/sysfs.c                         | 11 +++++++++++
>   5 files changed, 58 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
> index cad6c3dc1f9c..3500920ab7ce 100644
> --- a/Documentation/ABI/testing/sysfs-fs-f2fs
> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
> @@ -763,3 +763,17 @@ Date:		November 2023
>   Contact:	"Chao Yu" <chao@kernel.org>
>   Description:	It controls to enable/disable IO aware feature for background discard.
>   		By default, the value is 1 which indicates IO aware is on.
> +
> +What:		/sys/fs/f2fs/<disk>/blkzone_alloc_policy
> +Date:		July 2024
> +Contact:	"Yuanhong Liao" <liaoyuanhong@vivo.com>
> +Description:	The zone UFS we are currently using consists of two parts:
> +		conventional zones and sequential zones. It can be used to control which part
> +		to prioritize for writes, with a default value of 0.
> +
> +		========================  =========================================
> +		value					  description
> +		blkzone_alloc_policy = 0  Prioritize writing to sequential zones
> +		blkzone_alloc_policy = 1  Only allow writing to sequential zones
> +		blkzone_alloc_policy = 2  Prioritize writing to conventional zones
> +		========================  =========================================
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index f7ee6c5e371e..adefd19810ff 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -134,6 +134,12 @@ typedef u32 nid_t;
>   
>   #define COMPRESS_EXT_NUM		16
>   
> +enum blkzone_allocation_policy {
> +	BLKZONE_ALLOC_PRIOR_SEQ;	/* Prioritize writing to sequential zones */
> +	BLKZONE_ALLOC_ONLY_SEQ;		/* Only allow writing to sequential zones */
> +	BLKZONE_ALLOC_PRIOR_CONV;	/* Prioritize writing to conventional zones */

	BLKZONE_ALLOC_PRIOR_SEQ,	/* Prioritize writing to sequential zones */
	BLKZONE_ALLOC_ONLY_SEQ,		/* Only allow writing to sequential zones */
	BLKZONE_ALLOC_PRIOR_CONV	/* Prioritize writing to conventional zones */

> +};
> +
>   /*
>    * An implementation of an rwsem that is explicitly unfair to readers. This
>    * prevents priority inversion when a low-priority reader acquires the read lock
> @@ -1555,6 +1561,8 @@ struct f2fs_sb_info {
>   #ifdef CONFIG_BLK_DEV_ZONED
>   	unsigned int blocks_per_blkz;		/* F2FS blocks per zone */
>   	unsigned int max_open_zones;		/* max open zone resources of the zoned device */
> +	/* For adjust the priority writing position of data in zone UFS */
> +	unsigned int blkzone_alloc_policy;
>   #endif
>   
>   	/* for node-related operations */
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 4db1add43e36..026b61602113 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -2686,17 +2686,40 @@ static int get_new_segment(struct f2fs_sb_info *sbi,
>   			goto got_it;
>   	}
>   
> +#ifdef CONFIG_BLK_DEV_ZONED
>   	/*
>   	 * If we format f2fs on zoned storage, let's try to get pinned sections
>   	 * from beginning of the storage, which should be a conventional one.
>   	 */
>   	if (f2fs_sb_has_blkzoned(sbi)) {
> -		segno = pinning ? 0 : max(first_zoned_segno(sbi), *newseg);
> +		/* Prioritize writing to conventional zones */
> +		if (sbi->blkzone_alloc_policy == BLKZONE_ALLOC_PRIOR_CONV || pinning)
> +			segno = 0;
> +		else
> +			segno = max(first_zoned_segno(sbi), *newseg);
>   		hint = GET_SEC_FROM_SEG(sbi, segno);
>   	}
> +#endif
>   
>   find_other_zone:
>   	secno = find_next_zero_bit(free_i->free_secmap, MAIN_SECS(sbi), hint);
> +
> +#ifdef CONFIG_BLK_DEV_ZONED
> +	if (secno >= MAIN_SECS(sbi) && f2fs_sb_has_blkzoned(sbi)) {
> +		/* Write only to sequential zones */
> +		if (sbi->blkzone_alloc_policy == BLKZONE_ALLOC_ONLY_SEQ) {
> +			hint = GET_SEC_FROM_SEG(sbi, first_zoned_segno(sbi));
> +			secno = find_next_zero_bit(free_i->free_secmap, MAIN_SECS(sbi), hint);
> +		} else
> +			secno = find_first_zero_bit(free_i->free_secmap,
> +								MAIN_SECS(sbi));
> +		if (secno >= MAIN_SECS(sbi)) {
> +			ret = -ENOSPC;
> +			goto out_unlock;
> +		}
> +	}
> +#endif
> +
>   	if (secno >= MAIN_SECS(sbi)) {
>   		secno = find_first_zero_bit(free_i->free_secmap,
>   							MAIN_SECS(sbi));
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 4a1bc8f40f9a..95ae6de77939 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -4229,6 +4229,7 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
>   	sbi->aligned_blksize = true;
>   #ifdef CONFIG_BLK_DEV_ZONED
>   	sbi->max_open_zones = UINT_MAX;
> +	sbi->blkzone_alloc_policy = BLKZONE_ALLOC_PRIOR_SEQ;
>   #endif
>   
>   	for (i = 0; i < max_devices; i++) {
> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> index fee7ee45ceaa..63ff2d1647eb 100644
> --- a/fs/f2fs/sysfs.c
> +++ b/fs/f2fs/sysfs.c
> @@ -627,6 +627,15 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
>   	}
>   #endif
>   
> +#ifdef CONFIG_BLK_DEV_ZONED
> +	if (!strcmp(a->attr.name, "blkzone_alloc_policy")) {
> +		if (t < BLKZONE_ALLOC_PRIOR_SEQ || t > BLKZONE_ALLOC_PRIOR_CONV)
> +			return -EINVAL;
> +		sbi->blkzone_alloc_policy = t;
> +		return count;
> +	}
> +#endif
> +
>   #ifdef CONFIG_F2FS_FS_COMPRESSION
>   	if (!strcmp(a->attr.name, "compr_written_block") ||
>   		!strcmp(a->attr.name, "compr_saved_block")) {
> @@ -1033,6 +1042,7 @@ F2FS_SBI_GENERAL_RW_ATTR(warm_data_age_threshold);
>   F2FS_SBI_GENERAL_RW_ATTR(last_age_weight);
>   #ifdef CONFIG_BLK_DEV_ZONED
>   F2FS_SBI_GENERAL_RO_ATTR(unusable_blocks_per_sec);
> +F2FS_SBI_GENERAL_RW_ATTR(blkzone_alloc_policy);
>   #endif
>   
>   /* STAT_INFO ATTR */
> @@ -1187,6 +1197,7 @@ static struct attribute *f2fs_attrs[] = {
>   #endif
>   #ifdef CONFIG_BLK_DEV_ZONED
>   	ATTR_LIST(unusable_blocks_per_sec),
> +	ATTR_LIST(blkzone_alloc_policy),
>   #endif
>   #ifdef CONFIG_F2FS_FS_COMPRESSION
>   	ATTR_LIST(compr_written_block),


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