Re: [f2fs-dev][PATCH 3/4] f2fs: readahead contiguous current summary blocks in checkpoint

[Jaegeuk Kim]

Hi Chao,

On Mon, Dec 08, 2014 at 03:01:16PM +0800, Chao Yu wrote:
> Let's add readahead code for reading contiguous compact/normal summary blocks
> in checkpoint, then we will gain better performance in mount procedure.
> 
> Signed-off-by: Chao Yu <chao2.yu@xxxxxxxxxxx>
> ---
>  fs/f2fs/checkpoint.c |  2 +-
>  fs/f2fs/f2fs.h       |  2 +-
>  fs/f2fs/segment.c    | 21 ++++++++++++++++++---
>  3 files changed, 20 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index e0ff75e..aa2a21c 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -915,7 +915,7 @@ static void do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>  	ckpt->next_free_nid = cpu_to_le32(last_nid);
>  
>  	/* 2 cp  + n data seg summary + orphan inode blocks */
> -	data_sum_blocks = npages_for_summary_flush(sbi);
> +	data_sum_blocks = npages_for_summary_flush(sbi, false);
>  	if (data_sum_blocks < NR_CURSEG_DATA_TYPE)
>  		set_ckpt_flags(ckpt, CP_COMPACT_SUM_FLAG);
>  	else
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index d042813..fc88e8a 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -1393,7 +1393,7 @@ void refresh_sit_entry(struct f2fs_sb_info *, block_t, block_t);
>  void clear_prefree_segments(struct f2fs_sb_info *);
>  void release_discard_addrs(struct f2fs_sb_info *);
>  void discard_next_dnode(struct f2fs_sb_info *, block_t);
> -int npages_for_summary_flush(struct f2fs_sb_info *);
> +int npages_for_summary_flush(struct f2fs_sb_info *, bool);
>  void allocate_new_segments(struct f2fs_sb_info *);
>  int f2fs_trim_fs(struct f2fs_sb_info *, struct fstrim_range *);
>  struct page *get_sum_page(struct f2fs_sb_info *, unsigned int);
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 9a33e34..e3bec6e 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -731,7 +731,7 @@ static void __add_sum_entry(struct f2fs_sb_info *sbi, int type,
>  /*
>   * Calculate the number of current summary pages for writing
>   */
> -int npages_for_summary_flush(struct f2fs_sb_info *sbi)
> +int npages_for_summary_flush(struct f2fs_sb_info *sbi, bool for_ra)
>  {
>  	int valid_sum_count = 0;
>  	int i, sum_in_page;
> @@ -739,8 +739,13 @@ int npages_for_summary_flush(struct f2fs_sb_info *sbi)
>  	for (i = CURSEG_HOT_DATA; i <= CURSEG_COLD_DATA; i++) {
>  		if (sbi->ckpt->alloc_type[i] == SSR)
>  			valid_sum_count += sbi->blocks_per_seg;
> -		else
> -			valid_sum_count += curseg_blkoff(sbi, i);
> +		else {
> +			if (unlikely(for_ra))

IMO, unlikely is not appropriate for here.

Thanks,

> +				valid_sum_count += le16_to_cpu(
> +					F2FS_CKPT(sbi)->cur_data_blkoff[i]);
> +			else
> +				valid_sum_count += curseg_blkoff(sbi, i);
> +		}
>  	}
>  
>  	sum_in_page = (PAGE_CACHE_SIZE - 2 * SUM_JOURNAL_SIZE -
> @@ -1446,12 +1451,22 @@ static int restore_curseg_summaries(struct f2fs_sb_info *sbi)
>  	int err;
>  
>  	if (is_set_ckpt_flags(F2FS_CKPT(sbi), CP_COMPACT_SUM_FLAG)) {
> +		int npages = npages_for_summary_flush(sbi, true);
> +
> +		if (npages >= 2)
> +			ra_meta_pages(sbi, start_sum_block(sbi), npages,
> +								META_CP);
> +
>  		/* restore for compacted data summary */
>  		if (read_compacted_summaries(sbi))
>  			return -EINVAL;
>  		type = CURSEG_HOT_NODE;
>  	}
>  
> +	if (is_set_ckpt_flags(F2FS_CKPT(sbi), CP_UMOUNT_FLAG))
> +		ra_meta_pages(sbi, sum_blk_addr(sbi, NR_CURSEG_TYPE, type),
> +					NR_CURSEG_TYPE - type, META_CP);
> +
>  	for (; type <= CURSEG_COLD_NODE; type++) {
>  		err = read_normal_summaries(sbi, type);
>  		if (err)
> -- 
> 2.1.2
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