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Date: Thu, 30 May 2024 23:39:24 +0000
From: Jaegeuk Kim <jaegeuk@kernel.org>
To: Chao Yu <chao@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH v2 1/2] f2fs: use per-log target_bitmap to
 improve lookup performace of ssr allocation
Message-ID: <ZlkOLN0BugwQ2p5p@google.com>
References: <20240411082354.1691820-1-chao@kernel.org>
 <11d5d736-bae5-4a71-b400-087b8722893c@kernel.org>
 <03647897-8b1f-4c82-b2b6-0aa0704bed05@kernel.org>
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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@kernel.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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