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

[Jaegeuk Kim]

On 05/29, Chao Yu wrote:
> Ping,

Chao, sorry, I might need some time to take a look at the change cautiously.

> 
> 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@xxxxxxxxxx>
> > > ---
> > > 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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