Re: [PATCH] f2fs: introduce max_order_discard sysfs node

[Chao Yu]

On 2022/10/21 18:28, Yangtao Li wrote:
> The current max_order_discard is a fixed value,

max_ordered_discard?

> change it to be configurable through the sys node.
>
> Signed-off-by: Yangtao Li <frank.li@xxxxxxxx>
> ---
>   Documentation/ABI/testing/sysfs-fs-f2fs |  6 ++++++
>   fs/f2fs/f2fs.h                          |  3 +++
>   fs/f2fs/segment.c                       |  3 ++-
>   fs/f2fs/sysfs.c                         | 11 +++++++++++
>   4 files changed, 22 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
> index 11ce4a8bdacd..8faef2078a7a 100644
> --- a/Documentation/ABI/testing/sysfs-fs-f2fs
> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
> @@ -99,6 +99,12 @@ Description:	Controls the issue rate of discard commands that consist of small
>   		checkpoint is triggered, and issued during the checkpoint.
>   		By default, it is disabled with 0.
>   
> +What:		/sys/fs/f2fs/<disk>/max_order_discard
> +Date:		October 2022
> +Contact:	"Yangtao Li" <frank.li@xxxxxxxx>
> +Description:	Controls the maximum ordered discard, the unit size is one block(4KB).
> +		By default, it is disabled with 16.

By default, it is disabled with 16

Set it to 16 by default?

Thanks,

> +
>   What:		/sys/fs/f2fs/<disk>/max_discard_request
>   Date:		December 2021
>   Contact:	"Konstantin Vyshetsky" <vkon@xxxxxxxxxx>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index c444f3f86608..070dee37b915 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -330,6 +330,8 @@ struct discard_entry {
>   
>   /* default discard granularity of inner discard thread, unit: block count */
>   #define DEFAULT_DISCARD_GRANULARITY		16
> +/* default maximum discard granularity of ordered discard, unit: block count */
> +#define DEFAULT_MAX_ORDER_DISCARD_GRANULARITY	16
>   
>   /* max discard pend list number */
>   #define MAX_PLIST_NUM		512
> @@ -409,6 +411,7 @@ struct discard_cmd_control {
>   	unsigned int mid_discard_issue_time;	/* mid. interval between discard issue */
>   	unsigned int max_discard_issue_time;	/* max. interval between discard issue */
>   	unsigned int discard_granularity;	/* discard granularity */
> +	unsigned int max_order_discard; /* maximum discard granularity issued by lba order */
>   	unsigned int undiscard_blks;		/* # of undiscard blocks */
>   	unsigned int next_pos;			/* next discard position */
>   	atomic_t issued_discard;		/* # of issued discard */
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index acf3d3fa4363..921ec17a40ce 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -1448,7 +1448,7 @@ static int __issue_discard_cmd(struct f2fs_sb_info *sbi,
>   		if (i + 1 < dpolicy->granularity)
>   			break;
>   
> -		if (i < DEFAULT_DISCARD_GRANULARITY && dpolicy->ordered)
> +		if (i < dcc->max_order_discard && dpolicy->ordered)
>   			return __issue_discard_cmd_orderly(sbi, dpolicy);
>   
>   		pend_list = &dcc->pend_list[i];
> @@ -2046,6 +2046,7 @@ static int create_discard_cmd_control(struct f2fs_sb_info *sbi)
>   		return -ENOMEM;
>   
>   	dcc->discard_granularity = DEFAULT_DISCARD_GRANULARITY;
> +	dcc->max_order_discard = DEFAULT_MAX_ORDER_DISCARD_GRANULARITY;
>   	if (F2FS_OPTION(sbi).discard_unit == DISCARD_UNIT_SEGMENT)
>   		dcc->discard_granularity = sbi->blocks_per_seg;
>   	else if (F2FS_OPTION(sbi).discard_unit == DISCARD_UNIT_SECTION)
> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> index 555849d4c744..81f628aed2e5 100644
> --- a/fs/f2fs/sysfs.c
> +++ b/fs/f2fs/sysfs.c
> @@ -487,6 +487,15 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
>   		return count;
>   	}
>   
> +	if (!strcmp(a->attr.name, "max_order_discard")) {
> +		if (t == 0 || t > MAX_PLIST_NUM)
> +			return -EINVAL;
> +		if (!f2fs_block_unit_discard(sbi))
> +			return -EINVAL;
> +		*ui = t;
> +		return count;
> +	}
> +
>   	if (!strcmp(a->attr.name, "migration_granularity")) {
>   		if (t == 0 || t > sbi->segs_per_sec)
>   			return -EINVAL;
> @@ -801,6 +810,7 @@ F2FS_RW_ATTR(DCC_INFO, discard_cmd_control, min_discard_issue_time, min_discard_
>   F2FS_RW_ATTR(DCC_INFO, discard_cmd_control, mid_discard_issue_time, mid_discard_issue_time);
>   F2FS_RW_ATTR(DCC_INFO, discard_cmd_control, max_discard_issue_time, max_discard_issue_time);
>   F2FS_RW_ATTR(DCC_INFO, discard_cmd_control, discard_granularity, discard_granularity);
> +F2FS_RW_ATTR(DCC_INFO, discard_cmd_control, max_order_discard, max_order_discard);
>   F2FS_RW_ATTR(RESERVED_BLOCKS, f2fs_sb_info, reserved_blocks, reserved_blocks);
>   F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, batched_trim_sections, trim_sections);
>   F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, ipu_policy, ipu_policy);
> @@ -931,6 +941,7 @@ static struct attribute *f2fs_attrs[] = {
>   	ATTR_LIST(mid_discard_issue_time),
>   	ATTR_LIST(max_discard_issue_time),
>   	ATTR_LIST(discard_granularity),
> +	ATTR_LIST(max_order_discard),
>   	ATTR_LIST(pending_discard),
>   	ATTR_LIST(batched_trim_sections),
>   	ATTR_LIST(ipu_policy),