linux-kernel - Re: [PATCH] f2fs: allocate memory in batch in build_sit

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Date:   Wed, 10 Jul 2019 09:25:26 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>, Chao Yu <chao@...nel.org>
CC:     <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 2019/7/10 1:23, Jaegeuk Kim wrote:
> 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?

Total build_sit_info()'s elapsed time reduces from 20ms to 10ms on 128gb device.

Thanks,

> 
>>
>> 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
> .
>