On Jun 22, 2020, at 8:16 AM, Wang Shilong <wangshilong1991@xxxxxxxxx> wrote:
>
> From: Wang Shilong <wshilong@xxxxxxx>
>
> Now WAS_TRIMMED flag will be cleared if there are any blocks
> freed in this block group, this might be not good idea if there
> are only few blocks freed, since most of freed blocks have been
> issued discard before.
>
> So this patch tries to introduce another counter which record
> how many blocks freed since last time trimmed, WAS_TRIMMED flag
> will be only cleared if there are enough free blocks(default 128).
>
> Also expose a new sys interface min_freed_blocks_to_trim to tune
> default behavior.
>
> Cc: Shuichi Ihara <sihara@xxxxxxx>
> Cc: Andreas Dilger <adilger@xxxxxxxxx>
> Cc: Wang Shilong <wangshilong1991@xxxxxxxxx>
> Signed-off-by: Wang Shilong <wshilong@xxxxxxx>
Reviewed-by: Andreas Dilger <adilger@xxxxxxxxx>
> ---
> changelog v1->v2:
> init bb_freed_last_trimmed to be zero during setup
> ---
> fs/ext4/ext4.h | 7 +++++++
> fs/ext4/mballoc.c | 18 ++++++++++++++++--
> fs/ext4/sysfs.c | 2 ++
> 3 files changed, 25 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 252754da2f1b..2da86d1ebe3f 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -1240,6 +1240,9 @@ extern void ext4_set_bits(void *bm, int cur, int len);
> /* Metadata checksum algorithm codes */
> #define EXT4_CRC32C_CHKSUM 1
>
> +/* Default min freed blocks which we could clear TRIMMED flags */
> +#define DEFAULT_MIN_FREED_BLOCKS_TO_TRIM 128
> +
> /*
> * Structure of the super block
> */
> @@ -1533,6 +1536,9 @@ struct ext4_sb_info {
> /* the size of zero-out chunk */
> unsigned int s_extent_max_zeroout_kb;
>
> + /* Min freed blocks per group that we could run trim on it*/
> + unsigned long s_min_freed_blocks_to_trim;
> +
> unsigned int s_log_groups_per_flex;
> struct flex_groups * __rcu *s_flex_groups;
> ext4_group_t s_flex_groups_allocated;
> @@ -3125,6 +3131,7 @@ struct ext4_group_info {
> struct rb_root bb_free_root;
> ext4_grpblk_t bb_first_free; /* first free block */
> ext4_grpblk_t bb_free; /* total free blocks */
> + ext4_grpblk_t bb_freed_last_trimmed; /* total free blocks since last trimmed*/
> ext4_grpblk_t bb_fragments; /* nr of freespace fragments */
> ext4_grpblk_t bb_largest_free_order;/* order of largest frag in BG */
> struct list_head bb_prealloc_list;
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index 235a316584d0..52ab9ac5be86 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -2558,6 +2558,7 @@ int ext4_mb_add_groupinfo(struct super_block *sb, ext4_group_t group,
> init_rwsem(&meta_group_info[i]->alloc_sem);
> meta_group_info[i]->bb_free_root = RB_ROOT;
> meta_group_info[i]->bb_largest_free_order = -1; /* uninit */
> + meta_group_info[i]->bb_freed_last_trimmed = 0;
>
> mb_group_bb_bitmap_alloc(sb, meta_group_info[i], group);
> return 0;
> @@ -2763,6 +2764,8 @@ int ext4_mb_init(struct super_block *sb)
> sbi->s_mb_group_prealloc, sbi->s_stripe);
> }
>
> + sbi->s_min_freed_blocks_to_trim = DEFAULT_MIN_FREED_BLOCKS_TO_TRIM;
> +
> sbi->s_locality_groups = alloc_percpu(struct ext4_locality_group);
> if (sbi->s_locality_groups == NULL) {
> ret = -ENOMEM;
> @@ -5091,8 +5094,18 @@ void ext4_free_blocks(handle_t *handle, struct inode *inode,
> * If the volume is mounted with -o discard, online discard
> * is supported and the free blocks will be trimmed online.
> */
> - if (!test_opt(sb, DISCARD))
> - EXT4_MB_GDP_CLEAR_TRIMMED(gdp);
> + if (!test_opt(sb, DISCARD)) {
> + e4b.bd_info->bb_freed_last_trimmed += count;
> + /*
> + * Only clear the WAS_TRIMMED flag if there are
> + * several blocks freed, or if the group becomes
> + * totally 'empty'(free < num_itable_blocks + 2).
> + */
> + if (e4b.bd_info->bb_freed_last_trimmed >=
> + sbi->s_min_freed_blocks_to_trim ||
> + e4b.bd_info->bb_free < (sbi->s_itb_per_group + 2))
> + EXT4_MB_GDP_CLEAR_TRIMMED(gdp);
> + }
> ext4_group_desc_csum_set(sb, block_group, gdp);
> ext4_unlock_group(sb, block_group);
>
> @@ -5425,6 +5438,7 @@ ext4_trim_all_free(struct super_block *sb, ext4_group_t group,
> }
> ext4_lock_group(sb, group);
> EXT4_MB_GDP_SET_TRIMMED(gdp);
> + e4b.bd_info->bb_freed_last_trimmed = 0;
> ext4_group_desc_csum_set(sb, group, gdp);
> ext4_unlock_group(sb, group);
> err = ext4_handle_dirty_metadata(handle, NULL, gdp_bh);
> diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
> index 6c9fc9e21c13..8ee4e7e3f125 100644
> --- a/fs/ext4/sysfs.c
> +++ b/fs/ext4/sysfs.c
> @@ -216,6 +216,7 @@ EXT4_RW_ATTR_SBI_UI(mb_order2_req, s_mb_order2_reqs);
> EXT4_RW_ATTR_SBI_UI(mb_stream_req, s_mb_stream_request);
> EXT4_RW_ATTR_SBI_UI(mb_group_prealloc, s_mb_group_prealloc);
> EXT4_RW_ATTR_SBI_UI(extent_max_zeroout_kb, s_extent_max_zeroout_kb);
> +EXT4_RW_ATTR_SBI_UI(min_freed_blocks_to_trim, s_min_freed_blocks_to_trim);
> EXT4_ATTR(trigger_fs_error, 0200, trigger_test_error);
> EXT4_RW_ATTR_SBI_UI(err_ratelimit_interval_ms, s_err_ratelimit_state.interval);
> EXT4_RW_ATTR_SBI_UI(err_ratelimit_burst, s_err_ratelimit_state.burst);
> @@ -259,6 +260,7 @@ static struct attribute *ext4_attrs[] = {
> ATTR_LIST(mb_group_prealloc),
> ATTR_LIST(max_writeback_mb_bump),
> ATTR_LIST(extent_max_zeroout_kb),
> + ATTR_LIST(min_freed_blocks_to_trim),
> ATTR_LIST(trigger_fs_error),
> ATTR_LIST(err_ratelimit_interval_ms),
> ATTR_LIST(err_ratelimit_burst),
> --
> 2.25.4
>
Cheers, Andreas
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