RE: [f2fs-dev] [PATCH 2/2] f2fs: speed up shrinking extent tree entries

From: Chao Yu
Date: Tue Dec 22 2015 - 00:21:15 EST


Hi Jaegeuk,

We should update &total_zombie_tree whenever removing unreferenced
extent tree during shrinking:
- f2fs_shrink_extent_tree
if (!atomic_read(&et->refcount)) {
...
atomic_dec(&sbi->total_ext_tree);
atomic_dec(&sbi->total_zombie_tree);
...
}

Other parts look good to me. :)

Reviewed-by: Chao Yu <chao2.yu@xxxxxxxxxxx>

Thanks,

> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaegeuk@xxxxxxxxxx]
> Sent: Tuesday, December 22, 2015 11:39 AM
> To: linux-kernel@xxxxxxxxxxxxxxx; linux-fsdevel@xxxxxxxxxxxxxxx;
> linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx
> Cc: Jaegeuk Kim
> Subject: [f2fs-dev] [PATCH 2/2] f2fs: speed up shrinking extent tree entries
>
> If there is no candidates for shrinking slab entries, we don't need to traverse
> any trees at all.
>
> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> ---
> fs/f2fs/extent_cache.c | 12 ++++++++++++
> fs/f2fs/f2fs.h | 1 +
> fs/f2fs/shrinker.c | 2 +-
> 3 files changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
> index 0e97d6af..32693af 100644
> --- a/fs/f2fs/extent_cache.c
> +++ b/fs/f2fs/extent_cache.c
> @@ -71,6 +71,8 @@ static struct extent_tree *__grab_extent_tree(struct inode *inode)
> atomic_set(&et->refcount, 0);
> et->count = 0;
> atomic_inc(&sbi->total_ext_tree);
> + } else {
> + atomic_dec(&sbi->total_zombie_tree);
> }
> atomic_inc(&et->refcount);
> up_write(&sbi->extent_tree_lock);
> @@ -547,10 +549,14 @@ unsigned int f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int
> nr_shrink)
> unsigned int found;
> unsigned int node_cnt = 0, tree_cnt = 0;
> int remained;
> + bool do_free = false;
>
> if (!test_opt(sbi, EXTENT_CACHE))
> return 0;
>
> + if (!atomic_read(&sbi->total_zombie_tree))
> + goto free_node;
> +
> if (!down_write_trylock(&sbi->extent_tree_lock))
> goto out;
>
> @@ -580,6 +586,7 @@ unsigned int f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int
> nr_shrink)
> }
> up_write(&sbi->extent_tree_lock);
>
> +free_node:
> /* 2. remove LRU extent entries */
> if (!down_write_trylock(&sbi->extent_tree_lock))
> goto out;
> @@ -591,9 +598,13 @@ unsigned int f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int
> nr_shrink)
> if (!remained--)
> break;
> list_del_init(&en->list);
> + do_free = true;
> }
> spin_unlock(&sbi->extent_lock);
>
> + if (do_free == false)
> + goto unlock_out;
> +
> /*
> * reset ino for searching victims from beginning of global extent tree.
> */
> @@ -651,6 +662,7 @@ void f2fs_destroy_extent_tree(struct inode *inode)
>
> if (inode->i_nlink && !is_bad_inode(inode) && et->count) {
> atomic_dec(&et->refcount);
> + atomic_dec(&sbi->total_zombie_tree);
> return;
> }
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index a7f6191..90fb970 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -763,6 +763,7 @@ struct f2fs_sb_info {
> struct list_head extent_list; /* lru list for shrinker */
> spinlock_t extent_lock; /* locking extent lru list */
> atomic_t total_ext_tree; /* extent tree count */
> + atomic_t total_zombie_tree; /* extent zombie tree count */
> atomic_t total_ext_node; /* extent info count */
>
> /* basic filesystem units */
> diff --git a/fs/f2fs/shrinker.c b/fs/f2fs/shrinker.c
> index a11e099..93606f2 100644
> --- a/fs/f2fs/shrinker.c
> +++ b/fs/f2fs/shrinker.c
> @@ -32,7 +32,7 @@ static unsigned long __count_free_nids(struct f2fs_sb_info *sbi)
>
> static unsigned long __count_extent_cache(struct f2fs_sb_info *sbi)
> {
> - return atomic_read(&sbi->total_ext_tree) +
> + return atomic_read(&sbi->total_zombie_tree) +
> atomic_read(&sbi->total_ext_node);
> }
>
> --
> 2.5.4 (Apple Git-61)
>
>
> ------------------------------------------------------------------------------
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