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Date: Thu, 23 Feb 2017 10:21:09 +0800
From: Chao Yu <yuchao0@...wei.com>
To: Jaegeuk Kim <jaegeuk@...nel.org>
CC: <chao@...nel.org>, <linux-kernel@...r.kernel.org>,
<linux-f2fs-devel@...ts.sourceforge.net>
Subject: Re: [f2fs-dev] [PATCH] f2fs: introduce free nid bitmap
Hi Jaegeuk,
Thanks for all your comments, let me fix these and send v2 patch. :)
Thanks,
On 2017/2/23 7:26, Jaegeuk Kim wrote:
> Hi Chao,
>
> On 02/21, Chao Yu wrote:
>> In scenario of intensively node allocation, free nids will be ran out
>> soon, then it needs to stop to load free nids by traversing NAT blocks,
>> in worse case, if NAT blocks does not be cached in memory, it generates
>> IOs which slows down our foreground operations.
>>
>> In order to speed up node allocation, in this patch we introduce a new
>> free_nid_bitmap array, so there is an bitmap table for each NAT block,
>> Once the NAT block is loaded, related bitmap cache will be switched on,
>> and bitmap will be set during traversing nat entries in NAT block, later
>> we can query and update nid usage status in memory completely.
>>
>> With such implementation, I expect performance of node allocation can be
>> improved in the long-term after filesystem image is mounted.
>>
>> Signed-off-by: Chao Yu <yuchao0@...wei.com>
>> ---
>> fs/f2fs/f2fs.h | 2 +
>> fs/f2fs/node.c | 113 ++++++++++++++++++++++++++++++++++++++++++++++--
>> include/linux/f2fs_fs.h | 1 +
>> 3 files changed, 112 insertions(+), 4 deletions(-)
>>
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index 1c9f0cc8f027..659b63489c55 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -556,6 +556,8 @@ struct f2fs_nm_info {
>> unsigned int nid_cnt[MAX_NID_LIST]; /* the number of free node id */
>> spinlock_t nid_list_lock; /* protect nid lists ops */
>> struct mutex build_lock; /* lock for build free nids */
>> + char (*free_nid_bitmap)[NAT_ENTRY_BITMAP_SIZE];
>> + char *nat_block_bitmap;
>
> unsigned char *?
>
>>
>> /* for checkpoint */
>> char *nat_bitmap; /* NAT bitmap pointer */
>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
>> index b63bdb85ad66..8cef083b509d 100644
>> --- a/fs/f2fs/node.c
>> +++ b/fs/f2fs/node.c
>> @@ -1821,14 +1821,32 @@ static void remove_free_nid(struct f2fs_sb_info *sbi, nid_t nid)
>> kmem_cache_free(free_nid_slab, i);
>> }
>>
>> +void update_free_nid_bitmap(struct f2fs_sb_info *sbi, nid_t nid, bool set)
>> +{
>> + struct f2fs_nm_info *nm_i = NM_I(sbi);
>> + unsigned int nat_ofs = NAT_BLOCK_OFFSET(nid);
>> + unsigned int nid_ofs = nid - START_NID(nid);
>> +
>> + if (!test_bit_le(nat_ofs, nm_i->nat_block_bitmap))
>> + return;
>> +
>> + if (set)
>> + set_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]);
>> + else
>> + clear_bit_le(nid_ofs, nm_i->free_nid_bitmap[nat_ofs]);
>> +}
>> +
>> static void scan_nat_page(struct f2fs_sb_info *sbi,
>> struct page *nat_page, nid_t start_nid)
>> {
>> struct f2fs_nm_info *nm_i = NM_I(sbi);
>> struct f2fs_nat_block *nat_blk = page_address(nat_page);
>> block_t blk_addr;
>> + unsigned int nat_ofs = NAT_BLOCK_OFFSET(start_nid);
>> int i;
>>
>> + set_bit_le(nat_ofs, nm_i->nat_block_bitmap);
>> +
>> i = start_nid % NAT_ENTRY_PER_BLOCK;
>>
>> for (; i < NAT_ENTRY_PER_BLOCK; i++, start_nid++) {
>> @@ -1838,9 +1856,56 @@ static void scan_nat_page(struct f2fs_sb_info *sbi,
>>
>> blk_addr = le32_to_cpu(nat_blk->entries[i].block_addr);
>> f2fs_bug_on(sbi, blk_addr == NEW_ADDR);
>> - if (blk_addr == NULL_ADDR)
>> + if (blk_addr == NULL_ADDR) {
>> + update_free_nid_bitmap(sbi, start_nid, true);
>> add_free_nid(sbi, start_nid, true);
>> + } else {
>> + update_free_nid_bitmap(sbi, start_nid, false);
>> + }
>
> update_free_nid_bitmap(sbi, start_nid, blk_addr == NULL_ADDR);
>
>> + }
>> +}
>> +
>> +static void scan_free_nid_bits(struct f2fs_sb_info *sbi)
>> +{
>> + 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;
>> + unsigned int i, idx;
>> + unsigned int target = FREE_NID_PAGES * NAT_ENTRY_PER_BLOCK;
>> +
>> + down_read(&nm_i->nat_tree_lock);
>> +
>> + for (i = 0; i < nm_i->nat_blocks; i++) {
>> + if (!test_bit_le(i, nm_i->nat_block_bitmap))
>> + continue;
>> + for (idx = 0; idx < NAT_ENTRY_PER_BLOCK; idx++) {
>> + nid_t nid;
>> +
>> + if (!test_bit_le(idx, nm_i->free_nid_bitmap[i]))
>> + continue;
>> +
>> + nid = i * NAT_ENTRY_PER_BLOCK + idx;
>> + add_free_nid(sbi, nid, true);
>> +
>> + if (nm_i->nid_cnt[FREE_NID_LIST] >= target)
>> + goto out;
>> + }
>> + }
>> +out:
>> + down_read(&curseg->journal_rwsem);
>> + for (i = 0; i < nats_in_cursum(journal); i++) {
>> + block_t addr;
>> + nid_t nid;
>> +
>> + addr = le32_to_cpu(nat_in_journal(journal, i).block_addr);
>> + nid = le32_to_cpu(nid_in_journal(journal, i));
>> + if (addr == NULL_ADDR)
>> + add_free_nid(sbi, nid, true);
>> + else
>> + remove_free_nid(sbi, nid);
>> }
>> + up_read(&curseg->journal_rwsem);
>> + up_read(&nm_i->nat_tree_lock);
>> }
>>
>> static int scan_nat_bits(struct f2fs_sb_info *sbi)
>> @@ -1910,9 +1975,17 @@ static void __build_free_nids(struct f2fs_sb_info *sbi, bool sync, bool mount)
>> if (!sync && !available_free_memory(sbi, FREE_NIDS))
>> return;
>>
>> - /* try to find free nids with nat_bits */
>> - if (!mount && !scan_nat_bits(sbi) && nm_i->nid_cnt[FREE_NID_LIST])
>> - return;
>> + if (!mount) {
>> + /* try to find free nids in free_nid_bitmap */
>> + scan_free_nid_bits(sbi);
>> +
>> + if (nm_i->nid_cnt[FREE_NID_LIST])
>> + return;
>> +
>> + /* try to find free nids with nat_bits */
>> + if (!scan_nat_bits(sbi) && nm_i->nid_cnt[FREE_NID_LIST])
>> + return;
>> + }
>>
>> /* find next valid candidate */
>> if (is_set_ckpt_flags(sbi, CP_NAT_BITS_FLAG)) {
>> @@ -2005,6 +2078,9 @@ bool alloc_nid(struct f2fs_sb_info *sbi, nid_t *nid)
>> i->state = NID_ALLOC;
>> __insert_nid_to_list(sbi, i, ALLOC_NID_LIST, false);
>> nm_i->available_nids--;
>> +
>> + update_free_nid_bitmap(sbi, *nid, false);
>> +
>> spin_unlock(&nm_i->nid_list_lock);
>> return true;
>> }
>> @@ -2059,6 +2135,8 @@ void alloc_nid_failed(struct f2fs_sb_info *sbi, nid_t nid)
>>
>> nm_i->available_nids++;
>>
>> + update_free_nid_bitmap(sbi, nid, true);
>> +
>> spin_unlock(&nm_i->nid_list_lock);
>>
>> if (need_free)
>> @@ -2387,6 +2465,11 @@ static void __flush_nat_entry_set(struct f2fs_sb_info *sbi,
>> add_free_nid(sbi, nid, false);
>> spin_lock(&NM_I(sbi)->nid_list_lock);
>> NM_I(sbi)->available_nids++;
>> + update_free_nid_bitmap(sbi, nid, true);
>> + spin_unlock(&NM_I(sbi)->nid_list_lock);
>> + } else {
>> + spin_lock(&NM_I(sbi)->nid_list_lock);
>> + update_free_nid_bitmap(sbi, nid, false);
>> spin_unlock(&NM_I(sbi)->nid_list_lock);
>> }
>> }
>> @@ -2556,6 +2639,21 @@ static int init_node_manager(struct f2fs_sb_info *sbi)
>> return 0;
>> }
>>
>> +int init_free_nid_cache(struct f2fs_sb_info *sbi)
>> +{
>> + struct f2fs_nm_info *nm_i = NM_I(sbi);
>> +
>> + nm_i->free_nid_bitmap = f2fs_kvzalloc(nm_i->nat_blocks *
>> + NAT_ENTRY_BITMAP_SIZE, GFP_KERNEL);
>> + if (!nm_i->free_nid_bitmap)
>> + return -ENOMEM;
>> +
>> + nm_i->nat_block_bitmap = f2fs_kvzalloc(nm_i->nat_blocks, GFP_KERNEL);
>> + if (!nm_i->nat_block_bitmap)
>> + return -ENOMEM;
>
> This leads to update memory footprint in debug.c.
>
> Thanks,
>
>> + return 0;
>> +}
>> +
>> int build_node_manager(struct f2fs_sb_info *sbi)
>> {
>> int err;
>> @@ -2568,6 +2666,10 @@ int build_node_manager(struct f2fs_sb_info *sbi)
>> if (err)
>> return err;
>>
>> + err = init_free_nid_cache(sbi);
>> + if (err)
>> + return err;
>> +
>> build_free_nids(sbi, true, true);
>> return 0;
>> }
>> @@ -2626,6 +2728,9 @@ void destroy_node_manager(struct f2fs_sb_info *sbi)
>> }
>> up_write(&nm_i->nat_tree_lock);
>>
>> + kvfree(nm_i->nat_block_bitmap);
>> + kvfree(nm_i->free_nid_bitmap);
>> +
>> kfree(nm_i->nat_bitmap);
>> kfree(nm_i->nat_bits);
>> #ifdef CONFIG_F2FS_CHECK_FS
>> diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
>> index 1c92ace2e8f8..e2d239ed4c60 100644
>> --- a/include/linux/f2fs_fs.h
>> +++ b/include/linux/f2fs_fs.h
>> @@ -279,6 +279,7 @@ struct f2fs_node {
>> * For NAT entries
>> */
>> #define NAT_ENTRY_PER_BLOCK (PAGE_SIZE / sizeof(struct f2fs_nat_entry))
>> +#define NAT_ENTRY_BITMAP_SIZE ((NAT_ENTRY_PER_BLOCK + 7) / 8)
>>
>> struct f2fs_nat_entry {
>> __u8 version; /* latest version of cached nat entry */
>> --
>> 2.8.2.295.g3f1c1d0
>>
>>
>> ------------------------------------------------------------------------------
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>> _______________________________________________
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>
> .
>
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