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

[He YunLei <heyunlei@huawei.com>]

On 2015/12/22 13:20, Chao Yu wrote:
> 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@samsung.com>
>
> Thanks,
>
>> -----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 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@kernel.org>
>> ---
>>   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;
>>   	}
Hi,all
	here, sbi->total_ext_tree-- also should change to
	atomic_dec(&sbi->total_ext_tree);
Thanks,

>>
>> 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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