linux-kernel - Re: [f2fs-dev] [PATCH v2 1/2] f2fs: use per-log target_bitmap to improve lookup performace of ssr allocation

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Date: Wed, 29 May 2024 19:13:31 +0800
From: Chao Yu <chao@...nel.org>
To: jaegeuk@...nel.org
Cc: linux-kernel@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH v2 1/2] f2fs: use per-log target_bitmap to
 improve lookup performace of ssr allocation

Ping,

On 2024/4/23 10:07, Chao Yu wrote:
> Jaegeuk, any comments for this serials?
> 
> On 2024/4/11 16:23, Chao Yu wrote:
>> After commit 899fee36fac0 ("f2fs: fix to avoid data corruption by
>> forbidding SSR overwrite"), valid block bitmap of current openned
>> segment is fixed, let's introduce a per-log bitmap instead of temp
>> bitmap to avoid unnecessary calculation overhead whenever allocating
>> free slot w/ SSR allocator.
>>
>> Signed-off-by: Chao Yu <chao@...nel.org>
>> ---
>> v2:
>> - rebase to last dev-test branch.
>>   fs/f2fs/segment.c | 30 ++++++++++++++++++++++--------
>>   fs/f2fs/segment.h |  1 +
>>   2 files changed, 23 insertions(+), 8 deletions(-)
>>
>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>> index 6474b7338e81..af716925db19 100644
>> --- a/fs/f2fs/segment.c
>> +++ b/fs/f2fs/segment.c
>> @@ -2840,31 +2840,39 @@ static int new_curseg(struct f2fs_sb_info *sbi, int type, bool new_sec)
>>       return 0;
>>   }
>> -static int __next_free_blkoff(struct f2fs_sb_info *sbi,
>> -                    int segno, block_t start)
>> +static void __get_segment_bitmap(struct f2fs_sb_info *sbi,
>> +                    unsigned long *target_map,
>> +                    int segno)
>>   {
>>       struct seg_entry *se = get_seg_entry(sbi, segno);
>>       int entries = SIT_VBLOCK_MAP_SIZE / sizeof(unsigned long);
>> -    unsigned long *target_map = SIT_I(sbi)->tmp_map;
>>       unsigned long *ckpt_map = (unsigned long *)se->ckpt_valid_map;
>>       unsigned long *cur_map = (unsigned long *)se->cur_valid_map;
>>       int i;
>>       for (i = 0; i < entries; i++)
>>           target_map[i] = ckpt_map[i] | cur_map[i];
>> +}
>> +
>> +static int __next_free_blkoff(struct f2fs_sb_info *sbi, unsigned long *bitmap,
>> +                    int segno, block_t start)
>> +{
>> +    __get_segment_bitmap(sbi, bitmap, segno);
>> -    return __find_rev_next_zero_bit(target_map, BLKS_PER_SEG(sbi), start);
>> +    return __find_rev_next_zero_bit(bitmap, BLKS_PER_SEG(sbi), start);
>>   }
>>   static int f2fs_find_next_ssr_block(struct f2fs_sb_info *sbi,
>> -        struct curseg_info *seg)
>> +                    struct curseg_info *seg)
>>   {
>> -    return __next_free_blkoff(sbi, seg->segno, seg->next_blkoff + 1);
>> +    return __find_rev_next_zero_bit(seg->target_map,
>> +                BLKS_PER_SEG(sbi), seg->next_blkoff + 1);
>>   }
>>   bool f2fs_segment_has_free_slot(struct f2fs_sb_info *sbi, int segno)
>>   {
>> -    return __next_free_blkoff(sbi, segno, 0) < BLKS_PER_SEG(sbi);
>> +    return __next_free_blkoff(sbi, SIT_I(sbi)->tmp_map, segno, 0) <
>> +                            BLKS_PER_SEG(sbi);
>>   }
>>   /*
>> @@ -2890,7 +2898,8 @@ static int change_curseg(struct f2fs_sb_info *sbi, int type)
>>       reset_curseg(sbi, type, 1);
>>       curseg->alloc_type = SSR;
>> -    curseg->next_blkoff = __next_free_blkoff(sbi, curseg->segno, 0);
>> +    curseg->next_blkoff = __next_free_blkoff(sbi, curseg->target_map,
>> +                            curseg->segno, 0);
>>       sum_page = f2fs_get_sum_page(sbi, new_segno);
>>       if (IS_ERR(sum_page)) {
>> @@ -4635,6 +4644,10 @@ static int build_curseg(struct f2fs_sb_info *sbi)
>>                   sizeof(struct f2fs_journal), GFP_KERNEL);
>>           if (!array[i].journal)
>>               return -ENOMEM;
>> +        array[i].target_map = f2fs_kzalloc(sbi, SIT_VBLOCK_MAP_SIZE,
>> +                                GFP_KERNEL);
>> +        if (!array[i].target_map)
>> +            return -ENOMEM;
>>           if (i < NR_PERSISTENT_LOG)
>>               array[i].seg_type = CURSEG_HOT_DATA + i;
>>           else if (i == CURSEG_COLD_DATA_PINNED)
>> @@ -5453,6 +5466,7 @@ static void destroy_curseg(struct f2fs_sb_info *sbi)
>>       for (i = 0; i < NR_CURSEG_TYPE; i++) {
>>           kfree(array[i].sum_blk);
>>           kfree(array[i].journal);
>> +        kfree(array[i].target_map);
>>       }
>>       kfree(array);
>>   }
>> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
>> index e1c0f418aa11..10f3e44f036f 100644
>> --- a/fs/f2fs/segment.h
>> +++ b/fs/f2fs/segment.h
>> @@ -292,6 +292,7 @@ struct curseg_info {
>>       struct f2fs_summary_block *sum_blk;    /* cached summary block */
>>       struct rw_semaphore journal_rwsem;    /* protect journal area */
>>       struct f2fs_journal *journal;        /* cached journal info */
>> +    unsigned long *target_map;        /* bitmap for SSR allocator */
>>       unsigned char alloc_type;        /* current allocation type */
>>       unsigned short seg_type;        /* segment type like CURSEG_XXX_TYPE */
>>       unsigned int segno;            /* current segment number */
> 
> 
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