Sometimes I suffered the nat_tree_lock contention between f2fs_write_checkpoint
and f2fs_get_node_info. Commit a9419b6("f2fs: do not bother checkpoint by
f2fs_get_node_info") also mentioned that situation.My idea is, when flush nat entries, we can use some structures to record nat pages we may read, and readahead them before hold nat_tree_lock. Before impletement code, I did some survey and found a submittion in community. Subject: f2fs: use bucket sort to avoid tree lookup and list sort when nat flushing Link: https://lore.kernel.org/linux-f2fs-devel/20170520122435.17574-2-houpengy...@huawei.com/ This patch aims to improve nat entry set sort by using bucket. I steal that structure and readahead nat pages contain nat entry set which cannot be moved to journal according to dirty nat entry set bucket. By doing this, I think there are two benefits to reducing nat_tree_lock hold time when when flush nat entries. 1. avoid nat set tree lookup and sort 2. readahead nat pages before holding nat_tree_lock Signed-off-by: wangzijie <wangzij...@honor.com> --- fs/f2fs/f2fs.h | 1 + fs/f2fs/node.c | 70 ++++++++++++++++++++++++-------------------------- fs/f2fs/node.h | 2 +- 3 files changed, 35 insertions(+), 38 deletions(-) diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 46be75605..b27cc059f 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -975,6 +975,7 @@ struct f2fs_nm_info { struct radix_tree_root nat_set_root;/* root of the nat set cache */ struct f2fs_rwsem nat_tree_lock; /* protect nat entry tree */ struct list_head nat_entries; /* cached nat entry list (clean) */ + struct list_head nat_dirty_set[NAT_ENTRY_PER_BLOCK + 1]; /* store dirty nat set */ spinlock_t nat_list_lock; /* protect clean nat entry list */ unsigned int nat_cnt[MAX_NAT_STATE]; /* the # of cached nat entries */ unsigned int nat_blocks; /* # of nat blocks */ diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c index 27743b93e..87c975ee8 100644 --- a/fs/f2fs/node.c +++ b/fs/f2fs/node.c @@ -244,6 +244,12 @@ static void __del_from_nat_cache(struct f2fs_nm_info *nm_i, struct nat_entry *e) __free_nat_entry(e); } +static void __relocate_nat_entry_set(struct f2fs_nm_info *nm_i, + struct nat_entry_set *set) +{ + list_move_tail(&set->set_list, &nm_i->nat_dirty_set[set->entry_cnt]); +} + static struct nat_entry_set *__grab_nat_entry_set(struct f2fs_nm_info *nm_i, struct nat_entry *ne) { @@ -260,6 +266,7 @@ static struct nat_entry_set *__grab_nat_entry_set(struct f2fs_nm_info *nm_i, head->set = set; head->entry_cnt = 0; f2fs_radix_tree_insert(&nm_i->nat_set_root, set, head); + __relocate_nat_entry_set(nm_i, head); } return head; } @@ -279,8 +286,10 @@ static void __set_nat_cache_dirty(struct f2fs_nm_info *nm_i, * 2. update old block address to new one; */ if (!new_ne && (get_nat_flag(ne, IS_PREALLOC) || - !get_nat_flag(ne, IS_DIRTY))) + !get_nat_flag(ne, IS_DIRTY))) { head->entry_cnt++; + __relocate_nat_entry_set(nm_i, head); + } set_nat_flag(ne, IS_PREALLOC, new_ne); @@ -309,6 +318,7 @@ static void __clear_nat_cache_dirty(struct f2fs_nm_info *nm_i, set_nat_flag(ne, IS_DIRTY, false); set->entry_cnt--; + __relocate_nat_entry_set(nm_i, set); nm_i->nat_cnt[DIRTY_NAT]--; nm_i->nat_cnt[RECLAIMABLE_NAT]++; } @@ -2976,24 +2986,6 @@ static void remove_nats_in_journal(struct f2fs_sb_info *sbi) up_write(&curseg->journal_rwsem); } -static void __adjust_nat_entry_set(struct nat_entry_set *nes, - struct list_head *head, int max) -{ - struct nat_entry_set *cur; - - if (nes->entry_cnt >= max) - goto add_out; - - list_for_each_entry(cur, head, set_list) { - if (cur->entry_cnt >= nes->entry_cnt) { - list_add(&nes->set_list, cur->set_list.prev); - return; - } - } -add_out: - list_add_tail(&nes->set_list, head); -} - static void __update_nat_bits(struct f2fs_sb_info *sbi, nid_t start_nid, const struct f2fs_nat_block *nat_blk) { @@ -3095,6 +3087,7 @@ static int __flush_nat_entry_set(struct f2fs_sb_info *sbi, /* Allow dirty nats by node block allocation in write_begin */ if (!set->entry_cnt) { + list_del(&set->set_list); radix_tree_delete(&NM_I(sbi)->nat_set_root, set->set); kmem_cache_free(nat_entry_set_slab, set); } @@ -3109,11 +3102,8 @@ int f2fs_flush_nat_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc) struct f2fs_nm_info *nm_i = NM_I(sbi); struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA); struct f2fs_journal *journal = curseg->journal; - struct nat_entry_set *setvec[NAT_VEC_SIZE]; struct nat_entry_set *set, *tmp; - unsigned int found; - nid_t set_idx = 0; - LIST_HEAD(sets); + int i; int err = 0; /* @@ -3129,6 +3119,16 @@ int f2fs_flush_nat_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc) if (!nm_i->nat_cnt[DIRTY_NAT]) return 0; + /* readahead sets which cannot be moved to journal */ + if (!__has_cursum_space(journal, nm_i->nat_cnt[DIRTY_NAT], NAT_JOURNAL)) { + for (i = MAX_NAT_JENTRIES(journal); i <= NAT_ENTRY_PER_BLOCK; i++) { + list_for_each_entry_safe(set, tmp, &nm_i->nat_dirty_set[i], set_list) { + f2fs_ra_meta_pages(sbi, set->set, 1, + META_NAT, true); + } + } + } + f2fs_down_write(&nm_i->nat_tree_lock); /* @@ -3141,21 +3141,13 @@ int f2fs_flush_nat_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc) nm_i->nat_cnt[DIRTY_NAT], NAT_JOURNAL)) remove_nats_in_journal(sbi); - while ((found = __gang_lookup_nat_set(nm_i, - set_idx, NAT_VEC_SIZE, setvec))) { - unsigned idx; - - set_idx = setvec[found - 1]->set + 1; - for (idx = 0; idx < found; idx++) - __adjust_nat_entry_set(setvec[idx], &sets, - MAX_NAT_JENTRIES(journal)); - } - /* flush dirty nats in nat entry set */ - list_for_each_entry_safe(set, tmp, &sets, set_list) { - err = __flush_nat_entry_set(sbi, set, cpc); - if (err) - break; + for (i = 0; i <= NAT_ENTRY_PER_BLOCK; i++) { + list_for_each_entry_safe(set, tmp, &nm_i->nat_dirty_set[i], set_list) { + err = __flush_nat_entry_set(sbi, set, cpc); + if (err) + break; + } } f2fs_up_write(&nm_i->nat_tree_lock); @@ -3249,6 +3241,7 @@ static int init_node_manager(struct f2fs_sb_info *sbi) struct f2fs_nm_info *nm_i = NM_I(sbi); unsigned char *version_bitmap; unsigned int nat_segs; + int i; int err; nm_i->nat_blkaddr = le32_to_cpu(sb_raw->nat_blkaddr); @@ -3275,6 +3268,9 @@ static int init_node_manager(struct f2fs_sb_info *sbi) INIT_LIST_HEAD(&nm_i->nat_entries); spin_lock_init(&nm_i->nat_list_lock); + for (i = 0; i <= NAT_ENTRY_PER_BLOCK; i++) + INIT_LIST_HEAD(&nm_i->nat_dirty_set[i]); + mutex_init(&nm_i->build_lock); spin_lock_init(&nm_i->nid_list_lock); init_f2fs_rwsem(&nm_i->nat_tree_lock); diff --git a/fs/f2fs/node.h b/fs/f2fs/node.h index 030390543..d805d4ce7 100644 --- a/fs/f2fs/node.h +++ b/fs/f2fs/node.h @@ -158,7 +158,7 @@ enum mem_type { }; struct nat_entry_set { - struct list_head set_list; /* link with other nat sets */ + struct list_head set_list; /* link with nat sets which have same entry_cnt */ struct list_head entry_list; /* link with dirty nat entries */ nid_t set; /* set number*/ unsigned int entry_cnt; /* the # of nat entries in set */ -- 2.25.1 _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
