>-----Original Message-----
>From: Yuchao (T)
>Sent: Friday, March 16, 2018 5:47 PM
>To: heyunlei; [email protected]; [email protected]
>Cc: Wangbintian; Zhangdianfang (Euler)
>Subject: Re: [f2fs-dev][PATCH v3] f2fs: introduce a method to make nat journal
>more fresh
>
>On 2018/3/16 17:14, heyunlei wrote:
>>
>>
>>> -----Original Message-----
>>> From: Yuchao (T)
>>> Sent: Friday, March 16, 2018 4:49 PM
>>> To: heyunlei; [email protected]; [email protected]
>>> Cc: Wangbintian; Zhangdianfang (Euler)
>>> Subject: Re: [f2fs-dev][PATCH v3] f2fs: introduce a method to make nat
>>> journal more fresh
>>>
>>>
>>>
>>> On 2018/3/14 14:33, Yunlei He wrote:
>>>> This patch introduce a method to make nat journal more fresh:
>>>> i. sort set list using dirty entry number and cp version
>>>> average value.
>>>> ii. if meet with cache hit, update average version valus with
>>>> current cp version.
>>>>
>>>> With this patch, newly modified nat set will flush to journal,
>>>> and flush old nat set with same dirty entry number to nat area.
>>>>
>>>> Signed-off-by: Yunlei He <[email protected]>
>>>> ---
>>>> fs/f2fs/node.c | 45 ++++++++++++++++++++++++++-------------------
>>>> fs/f2fs/node.h | 4 +++-
>>>> 2 files changed, 29 insertions(+), 20 deletions(-)
>>>>
>>>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
>>>> index 177c438..74f6079 100644
>>>> --- a/fs/f2fs/node.c
>>>> +++ b/fs/f2fs/node.c
>>>> @@ -193,8 +193,8 @@ static void __del_from_nat_cache(struct f2fs_nm_info
>>>> *nm_i, struct nat_entry *e)
>>>> __free_nat_entry(e);
>>>> }
>>>>
>>>> -static void __set_nat_cache_dirty(struct f2fs_nm_info *nm_i,
>>>> - struct nat_entry *ne)
>>>> +static void __set_nat_cache_dirty(struct f2fs_sb_info *sbi, bool
>>>> remove_journal,
>>>> + struct f2fs_nm_info *nm_i, struct nat_entry *ne)
>>>> {
>>>> nid_t set = NAT_BLOCK_OFFSET(ne->ni.nid);
>>>> struct nat_entry_set *head;
>>>> @@ -207,9 +207,15 @@ static void __set_nat_cache_dirty(struct f2fs_nm_info
>>>> *nm_i,
>>>> INIT_LIST_HEAD(&head->set_list);
>>>> head->set = set;
>>>> head->entry_cnt = 0;
>>>> + head->cp_ver = 0;
>>>> f2fs_radix_tree_insert(&nm_i->nat_set_root, set, head);
>>>> }
>>>>
>>>> + /* journal hit case, try to locate set in journal */
>>>> + if (!remove_journal && head->entry_cnt <= NAT_JOURNAL_ENTRIES)
>>>> + head->cp_ver += div_u64(cur_cp_version(F2FS_CKPT(sbi)),
>>>> + NAT_JOURNAL_ENTRIES);
>>>> +
>>>> if (get_nat_flag(ne, IS_DIRTY))
>>>> goto refresh_list;
>>>
>>> else {
>>> update head version here?
>>> }
>>
>> Okay, if one nat entry update more than once, here will be overflow.
>>
>>>
>>>>
>>>> @@ -217,10 +223,7 @@ static void __set_nat_cache_dirty(struct f2fs_nm_info
>>>> *nm_i,
>>>> head->entry_cnt++;
>>>> set_nat_flag(ne, IS_DIRTY, true);
>>>> refresh_list:
>>>> - if (nat_get_blkaddr(ne) == NEW_ADDR)
>>>> - list_del_init(&ne->list);
>>>> - else
>>>> - list_move_tail(&ne->list, &head->entry_list);
>>>> + list_move_tail(&ne->list, &head->entry_list);
>>>
>>> For NEW_ADDR case, why we need to track this nat entry in entry_list?
>>
>> If new_blkaddr == NEW_ADDR, we don't need to call __set_nat_cache_dirty:
>
>But such entry is still in clean list, shrinker can easily remove it in
>out-of-memory condition.
Yes, you are right, my test doesn't cover low memory case. I 'll send a new
version.
Thanks.
>
>Thanks,
>
>> i nat entry with NEW_ADDR will increase dirty nat entry count in nat
>> set，which will cause
>> a nat set has large nat entry count（most is NEW_ADDR）， but fewer of
>> nat entries should
>> be written back in this checkpoint
>> ii nat entry with NEW_ADDR will call __set_nat_cache_dirty again, when
>> we write back its node
>> page, in this time, new_blkaddr != NEW_ADDR
>> So, I think we'd better bypass _set_nat_cache_dirty if blkaddr == NEW_ADDR
>>
>> Thanks.
>>
>>>
>>>> }
>>>>
>>>> static void __clear_nat_cache_dirty(struct f2fs_nm_info *nm_i,
>>>> @@ -357,7 +360,8 @@ static void set_node_addr(struct f2fs_sb_info *sbi,
>>>> struct node_info *ni,
>>>> nat_set_blkaddr(e, new_blkaddr);
>>>> if (new_blkaddr == NEW_ADDR || new_blkaddr == NULL_ADDR)
>>>> set_nat_flag(e, IS_CHECKPOINTED, false);
>>>> - __set_nat_cache_dirty(nm_i, e);
>>>> + if (new_blkaddr != NEW_ADDR)
>>>> + __set_nat_cache_dirty(sbi, false, nm_i, e);
>>>>
>>>> /* update fsync_mark if its inode nat entry is still alive */
>>>> if (ni->nid != ni->ino)
>>>> @@ -2395,14 +2399,14 @@ static void remove_nats_in_journal(struct
>>>> f2fs_sb_info *sbi)
>>>> spin_unlock(&nm_i->nid_list_lock);
>>>> }
>>>>
>>>> - __set_nat_cache_dirty(nm_i, ne);
>>>> + __set_nat_cache_dirty(sbi, true, nm_i, ne);
>>>> }
>>>> update_nats_in_cursum(journal, -i);
>>>> up_write(&curseg->journal_rwsem);
>>>> }
>>>>
>>>> -static void __adjust_nat_entry_set(struct nat_entry_set *nes,
>>>> - struct list_head *head, int max)
>>>> +static void __adjust_nat_entry_set(struct f2fs_sb_info *sbi,
>>>> + struct nat_entry_set *nes, struct list_head *head, int max)
>>>> {
>>>> struct nat_entry_set *cur;
>>>>
>>>> @@ -2410,7 +2414,9 @@ static void __adjust_nat_entry_set(struct
>>>> nat_entry_set *nes,
>>>> goto add_out;
>>>>
>>>> list_for_each_entry(cur, head, set_list) {
>>>> - if (cur->entry_cnt >= nes->entry_cnt) {
>>>> + if (cur->entry_cnt > nes->entry_cnt ||
>>>> + (cur->entry_cnt == nes->entry_cnt &&
>>>> + cur->cp_ver < nes->cp_ver)) {
>>>> list_add(&nes->set_list, cur->set_list.prev);
>>>> return;
>>>> }
>>>> @@ -2458,7 +2464,6 @@ static void __flush_nat_entry_set(struct
>>>> f2fs_sb_info *sbi,
>>>> struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA);
>>>> struct f2fs_journal *journal = curseg->journal;
>>>> nid_t start_nid = set->set * NAT_ENTRY_PER_BLOCK;
>>>> - bool to_journal = true;
>>>> struct f2fs_nat_block *nat_blk;
>>>> struct nat_entry *ne, *cur;
>>>> struct page *page = NULL;
>>>> @@ -2468,11 +2473,14 @@ static void __flush_nat_entry_set(struct
>>>> f2fs_sb_info *sbi,
>>>> * #1, flush nat entries to journal in current hot data summary block.
>>>> * #2, flush nat entries to nat page.
>>>> */
>>>> +
>>>> + set->to_journal = true;
>>>> +
>>>> if (enabled_nat_bits(sbi, cpc) ||
>>>> !__has_cursum_space(journal, set->entry_cnt, NAT_JOURNAL))
>>>> - to_journal = false;
>>>> + set->to_journal = false;
>>>>
>>>> - if (to_journal) {
>>>> + if (set->to_journal) {
>>>> down_write(&curseg->journal_rwsem);
>>>> } else {
>>>> page = get_next_nat_page(sbi, start_nid);
>>>> @@ -2488,7 +2496,7 @@ static void __flush_nat_entry_set(struct
>>>> f2fs_sb_info *sbi,
>>>>
>>>> f2fs_bug_on(sbi, nat_get_blkaddr(ne) == NEW_ADDR);
>>>>
>>>> - if (to_journal) {
>>>> + if (set->to_journal) {
>>>> offset = lookup_journal_in_cursum(journal,
>>>> NAT_JOURNAL, nid, 1);
>>>> f2fs_bug_on(sbi, offset < 0);
>>>> @@ -2509,7 +2517,7 @@ static void __flush_nat_entry_set(struct
>>>> f2fs_sb_info *sbi,
>>>> }
>>>> }
>>>>
>>>> - if (to_journal) {
>>>> + if (set->to_journal) {
>>>> up_write(&curseg->journal_rwsem);
>>>> } else {
>>>> __update_nat_bits(sbi, start_nid, page);
>>>> @@ -2517,7 +2525,7 @@ static void __flush_nat_entry_set(struct
>>>> f2fs_sb_info *sbi,
>>>> }
>>>>
>>>> /* Allow dirty nats by node block allocation in write_begin */
>>>> - if (!set->entry_cnt) {
>>>> + if (!set->to_journal) {
>>>
>>> if (!set->to_journal && !set->entry_cnt) ?
>>>
>>> Thanks,
>>>
>>>> radix_tree_delete(&NM_I(sbi)->nat_set_root, set->set);
>>>> kmem_cache_free(nat_entry_set_slab, set);
>>>> }
>>>> @@ -2556,7 +2564,7 @@ void flush_nat_entries(struct f2fs_sb_info *sbi,
>>>> struct cp_control *cpc)
>>>> unsigned idx;
>>>> set_idx = setvec[found - 1]->set + 1;
>>>> for (idx = 0; idx < found; idx++)
>>>> - __adjust_nat_entry_set(setvec[idx], &sets,
>>>> + __adjust_nat_entry_set(sbi, setvec[idx], &sets,
>>>> MAX_NAT_JENTRIES(journal));
>>>> }
>>>>
>>>> @@ -2565,7 +2573,6 @@ void flush_nat_entries(struct f2fs_sb_info *sbi,
>>>> struct cp_control *cpc)
>>>> __flush_nat_entry_set(sbi, set, cpc);
>>>>
>>>> up_write(&nm_i->nat_tree_lock);
>>>> - /* Allow dirty nats by node block allocation in write_begin */
>>>> }
>>>>
>>>> static int __get_nat_bitmaps(struct f2fs_sb_info *sbi)
>>>> diff --git a/fs/f2fs/node.h b/fs/f2fs/node.h
>>>> index 081ef0d..3cf9c8b6 100644
>>>> --- a/fs/f2fs/node.h
>>>> +++ b/fs/f2fs/node.h
>>>> @@ -148,7 +148,9 @@ struct nat_entry_set {
>>>> struct list_head set_list; /* link with other nat sets */
>>>> 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 */
>>>> + unsigned int entry_cnt:9; /* the # of nat entries in set */
>>>> + unsigned int to_journal:1; /* set flush to journal */
>>>> + __u64 cp_ver; /* cp version of this set modify */
>>>> };
>>>>
>>>> struct free_nid {
>>>>
>>
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