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.
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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