Re: [f2fs-dev] [PATCH v3 3/3] f2fs: support compressed file write/read amplifiction

[fengnan chang <fengnanchang@gmail.com>]

> 2022年7月24日 17:58，Chao Yu <chao@kernel.org> 写道：
> 
> On 2022/7/17 13:32, Fengnan Chang wrote:
>> From: Fengnan Chang <changfengnan@vivo.com>
>> Try to support compressed file write and amplifiction accounting.
>> Signed-off-by: Fengnan Chang <changfengnan@vivo.com>
>> ---
>>  fs/f2fs/data.c  | 26 +++++++++++++++++++++-----
>>  fs/f2fs/debug.c |  7 +++++--
>>  fs/f2fs/f2fs.h  | 34 ++++++++++++++++++++++++++++++++++
>>  3 files changed, 60 insertions(+), 7 deletions(-)
>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
>> index d2d2cfd54210..d0532958835b 100644
>> --- a/fs/f2fs/data.c
>> +++ b/fs/f2fs/data.c
>> @@ -2132,7 +2132,7 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret,
>>  	struct extent_info ei = {0, };
>>  	bool from_dnode = true;
>>  	int i;
>> -	int ret = 0;
>> +	int ret = 0, nr_cache_hit = 0;
>>    	f2fs_bug_on(sbi, f2fs_cluster_is_empty(cc));
>>  @@ -2223,6 +2223,7 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret,
>>  		if (f2fs_load_compressed_page(sbi, page, blkaddr)) {
>>  			if (atomic_dec_and_test(&dic->remaining_pages))
>>  				f2fs_decompress_cluster(dic);
>> +			nr_cache_hit++;
>>  			continue;
>>  		}
>>  @@ -2261,6 +2262,15 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret,
>>  		*last_block_in_bio = blkaddr;
>>  	}
>>  +	if (cc->nr_cpages - nr_cache_hit > cc->nr_rpages)
>> +		f2fs_i_compr_ra_blocks_update(inode,
>> +				cc->nr_cpages - nr_cache_hit - cc->nr_rpages,
> 
> I guess nr_rpages is not accurate here, due to it always equals to cluster_size,
> however user may just want to read one page data.
> 
> Hmm...I found iostat framework has already accounted FS_CDATA_READ_IO IO, how
> about adjusting it to support accounting compressed inode's read/write IOs?
> 

Of course we can support accounting compressed inode's read/write IOs.
But my initial thought was to provide a way to account write/read amplification for
compressed file. If adjust this to iostat,  it’s seems still can’t obtain read amplification.
Maybe I need add a argument for f2fs_read_multi_pages to get how many
page need to read in cluster, and calculate read amplification in f2fs_mpage_readpages?

Thanks.

> Thanks,
> 
>> +				true);
>> +	else
>> +		f2fs_i_compr_ra_blocks_update(inode,
>> +				cc->nr_rpages - cc->nr_cpages + nr_cache_hit,
>> +				false);
>> +
>>  	if (from_dnode)
>>  		f2fs_put_dnode(&dn);
>>  @@ -2929,11 +2939,11 @@ static int f2fs_write_cache_pages(struct address_space *mapping,
>>  	int range_whole = 0;
>>  	xa_mark_t tag;
>>  	int nwritten = 0;
>> -	int submitted = 0;
>> +	int submitted = 0, raw_dirty_pages = 0;
>>  	int i;
>>  -	if (get_dirty_pages(mapping->host) <=
>> -				SM_I(F2FS_M_SB(mapping))->min_hot_blocks)
>> +	raw_dirty_pages = get_dirty_pages(mapping->host);
>> +	if (raw_dirty_pages <= SM_I(F2FS_M_SB(mapping))->min_hot_blocks)
>>  		set_inode_flag(mapping->host, FI_HOT_DATA);
>>  	else
>>  		clear_inode_flag(mapping->host, FI_HOT_DATA);
>> @@ -3067,7 +3077,6 @@ static int f2fs_write_cache_pages(struct address_space *mapping,
>>  #endif
>>  			nwritten += submitted;
>>  			wbc->nr_to_write -= submitted;
>> -
>>  			if (unlikely(ret)) {
>>  				/*
>>  				 * keep nr_to_write, since vfs uses this to
>> @@ -3133,6 +3142,12 @@ static int f2fs_write_cache_pages(struct address_space *mapping,
>>  	if (bio)
>>  		f2fs_submit_merged_ipu_write(sbi, &bio, NULL);
>>  +	if (f2fs_compressed_file(inode)) {
>> +		if (nwritten > raw_dirty_pages)
>> +			f2fs_i_compr_wa_blocks_update(inode, nwritten - raw_dirty_pages, true);
>> +		else
>> +			f2fs_i_compr_wa_blocks_update(inode, raw_dirty_pages - nwritten, false);
>> +	}
>>  	return ret;
>>  }
>>  @@ -3482,6 +3497,7 @@ static int f2fs_write_begin(struct file *file, struct address_space *mapping,
>>  			err = ret;
>>  			goto fail;
>>  		} else if (ret) {
>> +			f2fs_i_compr_wa_blocks_update(inode, ret - 1, true);
>>  			return 0;
>>  		}
>>  	}
>> diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c
>> index c92625ef16d0..2bbf7fa49097 100644
>> --- a/fs/f2fs/debug.c
>> +++ b/fs/f2fs/debug.c
>> @@ -136,6 +136,8 @@ static void update_general_status(struct f2fs_sb_info *sbi)
>>  	si->inline_dir = atomic_read(&sbi->inline_dir);
>>  	si->compr_inode = atomic_read(&sbi->compr_inode);
>>  	si->compr_blocks = atomic64_read(&sbi->compr_blocks);
>> +	si->compr_wa_blocks = atomic64_read(&sbi->compr_wa_blocks);
>> +	si->compr_ra_blocks = atomic64_read(&sbi->compr_ra_blocks);
>>  	si->append = sbi->im[APPEND_INO].ino_num;
>>  	si->update = sbi->im[UPDATE_INO].ino_num;
>>  	si->orphans = sbi->im[ORPHAN_INO].ino_num;
>> @@ -383,8 +385,9 @@ static int stat_show(struct seq_file *s, void *v)
>>  			   si->inline_inode);
>>  		seq_printf(s, "  - Inline_dentry Inode: %u\n",
>>  			   si->inline_dir);
>> -		seq_printf(s, "  - Compressed Inode: %u, Blocks: %llu\n",
>> -			   si->compr_inode, si->compr_blocks);
>> +		seq_printf(s, "  - Compressed Inode: %u, Blocks: %llu, WA Blocks: %lld, RA Blocks %lld\n",
>> +			   si->compr_inode, si->compr_blocks,
>> +			   si->compr_wa_blocks, si->compr_ra_blocks);
>>  		seq_printf(s, "  - Orphan/Append/Update Inode: %u, %u, %u\n",
>>  			   si->orphans, si->append, si->update);
>>  		seq_printf(s, "\nMain area: %d segs, %d secs %d zones\n",
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index 06d0370fd760..9d0429e91718 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -1749,6 +1749,8 @@ struct f2fs_sb_info {
>>  	atomic_t inline_dir;			/* # of inline_dentry inodes */
>>  	atomic_t compr_inode;			/* # of compressed inodes */
>>  	atomic64_t compr_blocks;		/* # of compressed blocks */
>> +	atomic64_t compr_wa_blocks;		/* # of compressed WA blocks */
>> +	atomic64_t compr_ra_blocks;		/* # of compressed RA blocks */
>>  	atomic_t max_aw_cnt;			/* max # of atomic writes */
>>  	unsigned int io_skip_bggc;		/* skip background gc for in-flight IO */
>>  	unsigned int other_skip_bggc;		/* skip background gc for other reasons */
>> @@ -3829,6 +3831,8 @@ struct f2fs_stat_info {
>>  	int inline_xattr, inline_inode, inline_dir, append, update, orphans;
>>  	int compr_inode;
>>  	unsigned long long compr_blocks;
>> +	long long compr_wa_blocks;
>> +	long long compr_ra_blocks;
>>  	int aw_cnt, max_aw_cnt;
>>  	unsigned int valid_count, valid_node_count, valid_inode_count, discard_blks;
>>  	unsigned int bimodal, avg_vblocks;
>> @@ -3916,6 +3920,14 @@ static inline struct f2fs_stat_info *F2FS_STAT(struct f2fs_sb_info *sbi)
>>  		(atomic64_add(blocks, &F2FS_I_SB(inode)->compr_blocks))
>>  #define stat_sub_compr_blocks(inode, blocks)				\
>>  		(atomic64_sub(blocks, &F2FS_I_SB(inode)->compr_blocks))
>> +#define stat_add_compr_wa_blocks(inode, blocks)				\
>> +	(atomic64_add(blocks, &F2FS_I_SB(inode)->compr_wa_blocks))
>> +#define stat_sub_compr_wa_blocks(inode, blocks)				\
>> +	(atomic64_sub(blocks, &F2FS_I_SB(inode)->compr_wa_blocks))
>> +#define stat_add_compr_ra_blocks(inode, blocks)				\
>> +	(atomic64_add(blocks, &F2FS_I_SB(inode)->compr_ra_blocks))
>> +#define stat_sub_compr_ra_blocks(inode, blocks)				\
>> +	(atomic64_sub(blocks, &F2FS_I_SB(inode)->compr_ra_blocks))
>>  #define stat_inc_meta_count(sbi, blkaddr)				\
>>  	do {								\
>>  		if (blkaddr < SIT_I(sbi)->sit_base_addr)		\
>> @@ -4000,6 +4012,10 @@ void f2fs_update_sit_info(struct f2fs_sb_info *sbi);
>>  #define stat_dec_compr_inode(inode)			do { } while (0)
>>  #define stat_add_compr_blocks(inode, blocks)		do { } while (0)
>>  #define stat_sub_compr_blocks(inode, blocks)		do { } while (0)
>> +#define stat_add_compr_wa_blocks(inode, blocks)		do { } while (0)
>> +#define stat_sub_compr_wa_blocks(inode, blocks)		do { } while (0)
>> +#define stat_add_compr_ra_blocks(inode, blocks)		do { } while (0)
>> +#define stat_sub_compr_ra_blocks(inode, blocks)		do { } while (0)
>>  #define stat_update_max_atomic_write(inode)		do { } while (0)
>>  #define stat_inc_meta_count(sbi, blkaddr)		do { } while (0)
>>  #define stat_inc_seg_type(sbi, curseg)			do { } while (0)
>> @@ -4428,6 +4444,24 @@ static inline void f2fs_i_compr_blocks_update(struct inode *inode,
>>  	f2fs_mark_inode_dirty_sync(inode, true);
>>  }
>>  +static inline void f2fs_i_compr_wa_blocks_update(struct inode *inode,
>> +						u64 blocks, bool add)
>> +{
>> +	if (add)
>> +		stat_add_compr_wa_blocks(inode, blocks);
>> +	else
>> +		stat_sub_compr_wa_blocks(inode, blocks);
>> +}
>> +
>> +static inline void f2fs_i_compr_ra_blocks_update(struct inode *inode,
>> +						u64 blocks, bool add)
>> +{
>> +	if (add)
>> +		stat_add_compr_ra_blocks(inode, blocks);
>> +	else
>> +		stat_sub_compr_ra_blocks(inode, blocks);
>> +}
>> +
>>  static inline int block_unaligned_IO(struct inode *inode,
>>  				struct kiocb *iocb, struct iov_iter *iter)
>>  {



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