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Date:   Tue, 9 Jul 2019 10:23:47 -0700
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <chao@...nel.org>
Cc:     Chao Yu <yuchao0@...wei.com>,
        linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, Chen Gong <gongchen4@...wei.com>
Subject: Re: [PATCH] f2fs: allocate memory in batch in build_sit_info()

On 07/09, Chao Yu wrote:
> On 2019-7-9 7:46, Jaegeuk Kim wrote:
> > On 07/04, Chao Yu wrote:
> >> build_sit_info() allocate all bitmaps for each segment one by one,
> >> it's quite low efficiency, this pach changes to allocate large
> >> continuous memory at a time, and divide it and assign for each bitmaps
> > 
> > It may give more failure rate?
> 
> For android, I think there should be no problem, since while startup, memory
> should be sufficient for f2fs mount.
> For server or desktop, if there is any failure on memory allocation,
> f2fs_kzalloc will fallback to vmalloc, so that would not be worse than before,
> right?
> 
> Or if you worry about this really, could we add a fast path:

How much time can we really get with this big alloc?

> 
> build_sit_info()
>  - try allocate sit_i->bitmap
>   - success: divide memory
>  - fail: fallback to old method
> 
> Thanks,
> 
> > 
> >> of segment. For large size image, it can expect improving its mount
> >> speed.
> >>
> >> Signed-off-by: Chen Gong <gongchen4@...wei.com>
> >> Signed-off-by: Chao Yu <yuchao0@...wei.com>
> >> ---
> >>  fs/f2fs/segment.c | 51 +++++++++++++++++++++--------------------------
> >>  fs/f2fs/segment.h |  1 +
> >>  2 files changed, 24 insertions(+), 28 deletions(-)
> >>
> >> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> >> index 402fbbbb2d7c..73c803af1f31 100644
> >> --- a/fs/f2fs/segment.c
> >> +++ b/fs/f2fs/segment.c
> >> @@ -3929,7 +3929,7 @@ static int build_sit_info(struct f2fs_sb_info *sbi)
> >>  	struct f2fs_super_block *raw_super = F2FS_RAW_SUPER(sbi);
> >>  	struct sit_info *sit_i;
> >>  	unsigned int sit_segs, start;
> >> -	char *src_bitmap;
> >> +	char *src_bitmap, *bitmap;
> >>  	unsigned int bitmap_size;
> >>  
> >>  	/* allocate memory for SIT information */
> >> @@ -3950,27 +3950,31 @@ static int build_sit_info(struct f2fs_sb_info *sbi)
> >>  	if (!sit_i->dirty_sentries_bitmap)
> >>  		return -ENOMEM;
> >>  
> >> +#ifdef CONFIG_F2FS_CHECK_FS
> >> +	bitmap_size = MAIN_SEGS(sbi) * SIT_VBLOCK_MAP_SIZE * 4;
> >> +#else
> >> +	bitmap_size = MAIN_SEGS(sbi) * SIT_VBLOCK_MAP_SIZE * 3;
> >> +#endif
> >> +	sit_i->bitmap = f2fs_kzalloc(sbi, bitmap_size, GFP_KERNEL);
> >> +	if (!sit_i->bitmap)
> >> +		return -ENOMEM;
> >> +
> >> +	bitmap = sit_i->bitmap;
> >> +
> >>  	for (start = 0; start < MAIN_SEGS(sbi); start++) {
> >> -		sit_i->sentries[start].cur_valid_map
> >> -			= f2fs_kzalloc(sbi, SIT_VBLOCK_MAP_SIZE, GFP_KERNEL);
> >> -		sit_i->sentries[start].ckpt_valid_map
> >> -			= f2fs_kzalloc(sbi, SIT_VBLOCK_MAP_SIZE, GFP_KERNEL);
> >> -		if (!sit_i->sentries[start].cur_valid_map ||
> >> -				!sit_i->sentries[start].ckpt_valid_map)
> >> -			return -ENOMEM;
> >> +		sit_i->sentries[start].cur_valid_map = bitmap;
> >> +		bitmap += SIT_VBLOCK_MAP_SIZE;
> >> +
> >> +		sit_i->sentries[start].ckpt_valid_map = bitmap;
> >> +		bitmap += SIT_VBLOCK_MAP_SIZE;
> >>  
> >>  #ifdef CONFIG_F2FS_CHECK_FS
> >> -		sit_i->sentries[start].cur_valid_map_mir
> >> -			= f2fs_kzalloc(sbi, SIT_VBLOCK_MAP_SIZE, GFP_KERNEL);
> >> -		if (!sit_i->sentries[start].cur_valid_map_mir)
> >> -			return -ENOMEM;
> >> +		sit_i->sentries[start].cur_valid_map_mir = bitmap;
> >> +		bitmap += SIT_VBLOCK_MAP_SIZE;
> >>  #endif
> >>  
> >> -		sit_i->sentries[start].discard_map
> >> -			= f2fs_kzalloc(sbi, SIT_VBLOCK_MAP_SIZE,
> >> -							GFP_KERNEL);
> >> -		if (!sit_i->sentries[start].discard_map)
> >> -			return -ENOMEM;
> >> +		sit_i->sentries[start].discard_map = bitmap;
> >> +		bitmap += SIT_VBLOCK_MAP_SIZE;
> >>  	}
> >>  
> >>  	sit_i->tmp_map = f2fs_kzalloc(sbi, SIT_VBLOCK_MAP_SIZE, GFP_KERNEL);
> >> @@ -4440,21 +4444,12 @@ static void destroy_free_segmap(struct f2fs_sb_info *sbi)
> >>  static void destroy_sit_info(struct f2fs_sb_info *sbi)
> >>  {
> >>  	struct sit_info *sit_i = SIT_I(sbi);
> >> -	unsigned int start;
> >>  
> >>  	if (!sit_i)
> >>  		return;
> >>  
> >> -	if (sit_i->sentries) {
> >> -		for (start = 0; start < MAIN_SEGS(sbi); start++) {
> >> -			kvfree(sit_i->sentries[start].cur_valid_map);
> >> -#ifdef CONFIG_F2FS_CHECK_FS
> >> -			kvfree(sit_i->sentries[start].cur_valid_map_mir);
> >> -#endif
> >> -			kvfree(sit_i->sentries[start].ckpt_valid_map);
> >> -			kvfree(sit_i->sentries[start].discard_map);
> >> -		}
> >> -	}
> >> +	if (sit_i->sentries)
> >> +		kvfree(sit_i->bitmap);
> >>  	kvfree(sit_i->tmp_map);
> >>  
> >>  	kvfree(sit_i->sentries);
> >> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> >> index 2fd53462fa27..4d171b489130 100644
> >> --- a/fs/f2fs/segment.h
> >> +++ b/fs/f2fs/segment.h
> >> @@ -226,6 +226,7 @@ struct sit_info {
> >>  	block_t sit_base_addr;		/* start block address of SIT area */
> >>  	block_t sit_blocks;		/* # of blocks used by SIT area */
> >>  	block_t written_valid_blocks;	/* # of valid blocks in main area */
> >> +	char *bitmap;			/* all bitmaps pointer */
> >>  	char *sit_bitmap;		/* SIT bitmap pointer */
> >>  #ifdef CONFIG_F2FS_CHECK_FS
> >>  	char *sit_bitmap_mir;		/* SIT bitmap mirror */
> >> -- 
> >> 2.18.0.rc1

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