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    SubjectRE: [f2fs-dev] [PATCH 1/2] f2fs: use atomic variable for total_extent_tree
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    Hi Jaegeuk,

    > -----Original Message-----
    > From: Jaegeuk Kim [mailto:jaegeuk@kernel.org]
    > Sent: Tuesday, December 22, 2015 11:39 AM
    > To: linux-kernel@vger.kernel.org; linux-fsdevel@vger.kernel.org;
    > linux-f2fs-devel@lists.sourceforge.net
    > Cc: Jaegeuk Kim
    > Subject: [f2fs-dev] [PATCH 1/2] f2fs: use atomic variable for total_extent_tree
    >
    > It would be better to use atomic variable for total_extent_tree.

    total_extent_tree was protected by extent_tree_lock semaphore, so intention here
    is to make related calculation in available_free_memory or update_general_status
    more accurate, right?

    Thanks,

    >
    > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
    > ---
    > fs/f2fs/debug.c | 5 +++--
    > fs/f2fs/extent_cache.c | 8 ++++----
    > fs/f2fs/f2fs.h | 2 +-
    > fs/f2fs/node.c | 3 ++-
    > fs/f2fs/shrinker.c | 3 ++-
    > 5 files changed, 12 insertions(+), 9 deletions(-)
    >
    > diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c
    > index bb307e6..ed5dfcc 100644
    > --- a/fs/f2fs/debug.c
    > +++ b/fs/f2fs/debug.c
    > @@ -38,7 +38,7 @@ static void update_general_status(struct f2fs_sb_info *sbi)
    > si->hit_rbtree = atomic64_read(&sbi->read_hit_rbtree);
    > si->hit_total = si->hit_largest + si->hit_cached + si->hit_rbtree;
    > si->total_ext = atomic64_read(&sbi->total_hit_ext);
    > - si->ext_tree = sbi->total_ext_tree;
    > + si->ext_tree = atomic_read(&sbi->total_ext_tree);
    > si->ext_node = atomic_read(&sbi->total_ext_node);
    > si->ndirty_node = get_pages(sbi, F2FS_DIRTY_NODES);
    > si->ndirty_dent = get_pages(sbi, F2FS_DIRTY_DENTS);
    > @@ -193,7 +193,8 @@ get_cache:
    > si->cache_mem += si->inmem_pages * sizeof(struct inmem_pages);
    > for (i = 0; i <= UPDATE_INO; i++)
    > si->cache_mem += sbi->im[i].ino_num * sizeof(struct ino_entry);
    > - si->cache_mem += sbi->total_ext_tree * sizeof(struct extent_tree);
    > + si->cache_mem += atomic_read(&sbi->total_ext_tree) *
    > + sizeof(struct extent_tree);
    > si->cache_mem += atomic_read(&sbi->total_ext_node) *
    > sizeof(struct extent_node);
    >
    > diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
    > index e86e9f1e..0e97d6af 100644
    > --- a/fs/f2fs/extent_cache.c
    > +++ b/fs/f2fs/extent_cache.c
    > @@ -70,7 +70,7 @@ static struct extent_tree *__grab_extent_tree(struct inode *inode)
    > rwlock_init(&et->lock);
    > atomic_set(&et->refcount, 0);
    > et->count = 0;
    > - sbi->total_ext_tree++;
    > + atomic_inc(&sbi->total_ext_tree);
    > }
    > atomic_inc(&et->refcount);
    > up_write(&sbi->extent_tree_lock);
    > @@ -570,7 +570,7 @@ unsigned int f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int
    > nr_shrink)
    >
    > radix_tree_delete(root, et->ino);
    > kmem_cache_free(extent_tree_slab, et);
    > - sbi->total_ext_tree--;
    > + atomic_dec(&sbi->total_ext_tree);
    > tree_cnt++;
    >
    > if (node_cnt + tree_cnt >= nr_shrink)
    > @@ -663,7 +663,7 @@ void f2fs_destroy_extent_tree(struct inode *inode)
    > f2fs_bug_on(sbi, atomic_read(&et->refcount) || et->count);
    > radix_tree_delete(&sbi->extent_tree_root, inode->i_ino);
    > kmem_cache_free(extent_tree_slab, et);
    > - sbi->total_ext_tree--;
    > + atomic_dec(&sbi->total_ext_tree);
    > up_write(&sbi->extent_tree_lock);
    >
    > F2FS_I(inode)->extent_tree = NULL;
    > @@ -715,7 +715,7 @@ void init_extent_cache_info(struct f2fs_sb_info *sbi)
    > init_rwsem(&sbi->extent_tree_lock);
    > INIT_LIST_HEAD(&sbi->extent_list);
    > spin_lock_init(&sbi->extent_lock);
    > - sbi->total_ext_tree = 0;
    > + atomic_set(&sbi->total_ext_tree, 0);
    > atomic_set(&sbi->total_ext_node, 0);
    > }
    >
    > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
    > index 19beabe..a7f6191 100644
    > --- a/fs/f2fs/f2fs.h
    > +++ b/fs/f2fs/f2fs.h
    > @@ -762,7 +762,7 @@ struct f2fs_sb_info {
    > struct rw_semaphore extent_tree_lock; /* locking extent radix tree */
    > struct list_head extent_list; /* lru list for shrinker */
    > spinlock_t extent_lock; /* locking extent lru list */
    > - int total_ext_tree; /* extent tree count */
    > + atomic_t total_ext_tree; /* extent tree count */
    > atomic_t total_ext_node; /* extent info count */
    >
    > /* basic filesystem units */
    > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
    > index d842b19..6cc8ac7 100644
    > --- a/fs/f2fs/node.c
    > +++ b/fs/f2fs/node.c
    > @@ -65,7 +65,8 @@ bool available_free_memory(struct f2fs_sb_info *sbi, int type)
    > sizeof(struct ino_entry)) >> PAGE_CACHE_SHIFT;
    > res = mem_size < ((avail_ram * nm_i->ram_thresh / 100) >> 1);
    > } else if (type == EXTENT_CACHE) {
    > - mem_size = (sbi->total_ext_tree * sizeof(struct extent_tree) +
    > + mem_size = (atomic_read(&sbi->total_ext_tree) *
    > + sizeof(struct extent_tree) +
    > atomic_read(&sbi->total_ext_node) *
    > sizeof(struct extent_node)) >> PAGE_CACHE_SHIFT;
    > res = mem_size < ((avail_ram * nm_i->ram_thresh / 100) >> 1);
    > diff --git a/fs/f2fs/shrinker.c b/fs/f2fs/shrinker.c
    > index da0d8e0..a11e099 100644
    > --- a/fs/f2fs/shrinker.c
    > +++ b/fs/f2fs/shrinker.c
    > @@ -32,7 +32,8 @@ static unsigned long __count_free_nids(struct f2fs_sb_info *sbi)
    >
    > static unsigned long __count_extent_cache(struct f2fs_sb_info *sbi)
    > {
    > - return sbi->total_ext_tree + atomic_read(&sbi->total_ext_node);
    > + return atomic_read(&sbi->total_ext_tree) +
    > + atomic_read(&sbi->total_ext_node);
    > }
    >
    > unsigned long f2fs_shrink_count(struct shrinker *shrink,
    > --
    > 2.5.4 (Apple Git-61)
    >
    >
    > ------------------------------------------------------------------------------
    > _______________________________________________
    > Linux-f2fs-devel mailing list
    > Linux-f2fs-devel@lists.sourceforge.net
    > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel



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