Messages in this thread Patch in this message | | | From | Yunlong Song <> | Subject | [PATCH 4/5] f2fs: let BG_GC check every dirty segments and gc over a threshold | Date | Mon, 23 Jul 2018 22:10:21 +0800 |
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BG_GC is triggered in idle time, so it is better check every dirty segment and finds the best victim to gc. Otherwise, BG_GC will be limited to only 8G areas, and probably select a victim which has nearly full of valid blocks, resulting a big WAI. Besides, we also add a bggc_threshold (which is the old "fggc_threshold", so revert commit "299254") to stop BG_GC when there is no good choice. This is especially good for large section case to reduce WAI.
Signed-off-by: Yunlong Song <yunlong.song@huawei.com> --- fs/f2fs/f2fs.h | 2 ++ fs/f2fs/gc.c | 23 ++++++++++++++++++++--- fs/f2fs/segment.h | 9 +++++++++ 3 files changed, 31 insertions(+), 3 deletions(-)
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index f8a7b42..24a9d7f 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -1220,6 +1220,8 @@ struct f2fs_sb_info { unsigned int cur_fg_victim_sec; /* current FG_GC victim section num */ unsigned int cur_bg_victim_sec; /* current BG_GC victim section num */ unsigned int gc_mode; /* current GC state */ + /* threshold for selecting bg victims */ + u64 bggc_threshold; /* for skip statistic */ unsigned long long skipped_atomic_files[2]; /* FG_GC and BG_GC */ diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c index 0e7a265..21e8d59 100644 --- a/fs/f2fs/gc.c +++ b/fs/f2fs/gc.c @@ -189,9 +189,8 @@ static void select_policy(struct f2fs_sb_info *sbi, int gc_type, p->ofs_unit = sbi->segs_per_sec; } - /* we need to check every dirty segments in the FG_GC case */ - if (gc_type != FG_GC && - (sbi->gc_mode != GC_URGENT) && + /* we need to check every dirty segments in the GC case */ + if (p->alloc_mode == SSR && p->max_search > sbi->max_victim_search) p->max_search = sbi->max_victim_search; @@ -230,6 +229,10 @@ static unsigned int check_bg_victims(struct f2fs_sb_info *sbi) for_each_set_bit(secno, dirty_i->victim_secmap, MAIN_SECS(sbi)) { if (sec_usage_check(sbi, secno)) continue; + + if (no_bggc_candidate(sbi, secno)) + continue; + clear_bit(secno, dirty_i->victim_secmap); return GET_SEG_FROM_SEC(sbi, secno); } @@ -368,6 +371,10 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi, if (sec_usage_check(sbi, secno)) goto next; + if (gc_type == BG_GC && p.alloc_mode == LFS && + no_bggc_candidate(sbi, secno)) + goto next; + cost = get_gc_cost(sbi, segno, &p); if (p.min_cost > cost) { @@ -1140,8 +1147,18 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync, void f2fs_build_gc_manager(struct f2fs_sb_info *sbi) { + u64 main_count, resv_count, ovp_count; + DIRTY_I(sbi)->v_ops = &default_v_ops; + /* threshold of # of valid blocks in a section for victims of BG_GC */ + main_count = SM_I(sbi)->main_segments << sbi->log_blocks_per_seg; + resv_count = SM_I(sbi)->reserved_segments << sbi->log_blocks_per_seg; + ovp_count = SM_I(sbi)->ovp_segments << sbi->log_blocks_per_seg; + + sbi->bggc_threshold = div64_u64((main_count - ovp_count) * + BLKS_PER_SEC(sbi), (main_count - resv_count)); + sbi->gc_pin_file_threshold = DEF_GC_FAILED_PINNED_FILES; /* give warm/cold data area from slower device */ diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h index b21bb96..932e59b 100644 --- a/fs/f2fs/segment.h +++ b/fs/f2fs/segment.h @@ -785,6 +785,15 @@ static inline block_t sum_blk_addr(struct f2fs_sb_info *sbi, int base, int type) - (base + 1) + type; } +static inline bool no_bggc_candidate(struct f2fs_sb_info *sbi, + unsigned int secno) +{ + if (get_valid_blocks(sbi, GET_SEG_FROM_SEC(sbi, secno), true) > + sbi->bggc_threshold) + return true; + return false; +} + static inline bool sec_usage_check(struct f2fs_sb_info *sbi, unsigned int secno) { if (IS_CURSEC(sbi, secno) || (sbi->cur_fg_victim_sec == secno) || -- 1.8.5.2
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