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Date: Tue, 24 Jun 2014 06:40:53 +0900
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <chao2.yu@...sung.com>
Cc: Changman Lee <cm224.lee@...sung.com>,
linux-f2fs-devel@...ts.sourceforge.net,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [f2fs-dev] [PATCH v2 RESEND] f2fs: refactor flush_nat_entries
codes for reducing NAT writes
Hi Chao,
Thank you for the patch. :)
Just one minor suggestion.
[snip]
> /*
> @@ -1792,80 +1864,87 @@ void flush_nat_entries(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_summary_block *sum = curseg->sum_blk;
> - struct nat_entry *ne, *cur;
> - struct page *page = NULL;
> - struct f2fs_nat_block *nat_blk = NULL;
> - nid_t start_nid = 0, end_nid = 0;
> - bool flushed;
> -
> - flushed = flush_nats_in_journal(sbi);
> -
> - if (!flushed)
> - mutex_lock(&curseg->curseg_mutex);
> -
> - /* 1) flush dirty nat caches */
> - list_for_each_entry_safe(ne, cur, &nm_i->dirty_nat_entries, list) {
> - nid_t nid;
> - struct f2fs_nat_entry raw_ne;
> - int offset = -1;
> -
> - if (nat_get_blkaddr(ne) == NEW_ADDR)
> - continue;
> + struct nat_entry_set *nes, *tmp;
> + struct list_head *head = &nm_i->nat_entry_set;
> + bool to_journal = true;
>
> - nid = nat_get_nid(ne);
> + /* merge nat entries of dirty list to nat entry set temporarily */
> + merge_nats_in_set(sbi);
>
> - if (flushed)
> - goto to_nat_page;
> + if (!__has_cursum_space(sum, nm_i->dirty_nat_cnt)) {
> + /*
> + * if there are no enough space in journal to store dirty nat
> + * entries, remove all entries from journal and merge them
> + * into nat entry set.
> + */
> + remove_nats_in_journal(sbi);
> + merge_nats_in_set(sbi);
> + }
How about this?
/*
* if there are no enough space in journal to store dirty nat
* entries, remove all entries from journal and merge them
* into nat entry set.
*/
if (!__has_cursum_space(sum, nm_i->dirty_nat_cnt))
remove_nats_in_journal(sbi);
/* merge nat entries of dirty list to nat entry set temporarily */
merge_nats_in_set(sbi);
Thanks,
>
> - /* if there is room for nat enries in curseg->sumpage */
> - offset = lookup_journal_in_cursum(sum, NAT_JOURNAL, nid, 1);
> - if (offset >= 0) {
> - raw_ne = nat_in_journal(sum, offset);
> - goto flush_now;
> - }
> -to_nat_page:
> - if (!page || (start_nid > nid || nid > end_nid)) {
> - if (page) {
> - f2fs_put_page(page, 1);
> - page = NULL;
> - }
> - start_nid = START_NID(nid);
> - end_nid = start_nid + NAT_ENTRY_PER_BLOCK - 1;
> + if (!nm_i->dirty_nat_cnt)
> + return;
>
> - /*
> - * get nat block with dirty flag, increased reference
> - * count, mapped and lock
> - */
> + /*
> + * there are two steps to flush nat entries:
> + * #1, flush nat entries to journal in current hot data summary block.
> + * #2, flush nat entries to nat page.
> + */
> + list_for_each_entry_safe(nes, tmp, head, set_list) {
> + struct f2fs_nat_block *nat_blk;
> + struct nat_entry *ne, *cur;
> + struct page *page;
> + nid_t start_nid = nes->start_nid;
> +
> + if (to_journal && !__has_cursum_space(sum, nes->entry_cnt))
> + to_journal = false;
> +
> + if (to_journal) {
> + mutex_lock(&curseg->curseg_mutex);
> + } else {
> page = get_next_nat_page(sbi, start_nid);
> nat_blk = page_address(page);
> + f2fs_bug_on(!nat_blk);
> }
>
> - f2fs_bug_on(!nat_blk);
> - raw_ne = nat_blk->entries[nid - start_nid];
> -flush_now:
> - raw_nat_from_node_info(&raw_ne, &ne->ni);
> -
> - if (offset < 0) {
> - nat_blk->entries[nid - start_nid] = raw_ne;
> - } else {
> - nat_in_journal(sum, offset) = raw_ne;
> - nid_in_journal(sum, offset) = cpu_to_le32(nid);
> - }
> + /* flush dirty nats in nat entry set */
> + list_for_each_entry_safe(ne, cur, &nes->entry_list, list) {
> + struct f2fs_nat_entry *raw_ne;
> + nid_t nid = nat_get_nid(ne);
> + int offset;
> +
> + if (to_journal) {
> + offset = lookup_journal_in_cursum(sum,
> + NAT_JOURNAL, nid, 1);
> + f2fs_bug_on(offset < 0);
> + raw_ne = &nat_in_journal(sum, offset);
> + nid_in_journal(sum, offset) = cpu_to_le32(nid);
> + } else {
> + raw_ne = &nat_blk->entries[nid - start_nid];
> + }
> + raw_nat_from_node_info(raw_ne, &ne->ni);
>
> - if (nat_get_blkaddr(ne) == NULL_ADDR &&
> + if (nat_get_blkaddr(ne) == NULL_ADDR &&
> add_free_nid(sbi, nid, false) <= 0) {
> - write_lock(&nm_i->nat_tree_lock);
> - __del_from_nat_cache(nm_i, ne);
> - write_unlock(&nm_i->nat_tree_lock);
> - } else {
> - write_lock(&nm_i->nat_tree_lock);
> - __clear_nat_cache_dirty(nm_i, ne);
> - write_unlock(&nm_i->nat_tree_lock);
> + write_lock(&nm_i->nat_tree_lock);
> + __del_from_nat_cache(nm_i, ne);
> + write_unlock(&nm_i->nat_tree_lock);
> + } else {
> + write_lock(&nm_i->nat_tree_lock);
> + __clear_nat_cache_dirty(nm_i, ne);
> + write_unlock(&nm_i->nat_tree_lock);
> + }
> }
> +
> + if (to_journal)
> + mutex_unlock(&curseg->curseg_mutex);
> + else
> + f2fs_put_page(page, 1);
> +
> + release_nat_entry_set(nes, nm_i);
> }
> - if (!flushed)
> - mutex_unlock(&curseg->curseg_mutex);
> - f2fs_put_page(page, 1);
> +
> + f2fs_bug_on(!list_empty(head));
> + f2fs_bug_on(nm_i->dirty_nat_cnt);
> }
>
> static int init_node_manager(struct f2fs_sb_info *sbi)
> @@ -1894,6 +1973,7 @@ static int init_node_manager(struct f2fs_sb_info *sbi)
> INIT_RADIX_TREE(&nm_i->nat_root, GFP_ATOMIC);
> INIT_LIST_HEAD(&nm_i->nat_entries);
> INIT_LIST_HEAD(&nm_i->dirty_nat_entries);
> + INIT_LIST_HEAD(&nm_i->nat_entry_set);
>
> mutex_init(&nm_i->build_lock);
> spin_lock_init(&nm_i->free_nid_list_lock);
> @@ -1974,19 +2054,30 @@ int __init create_node_manager_caches(void)
> nat_entry_slab = f2fs_kmem_cache_create("nat_entry",
> sizeof(struct nat_entry));
> if (!nat_entry_slab)
> - return -ENOMEM;
> + goto fail;
>
> free_nid_slab = f2fs_kmem_cache_create("free_nid",
> sizeof(struct free_nid));
> - if (!free_nid_slab) {
> - kmem_cache_destroy(nat_entry_slab);
> - return -ENOMEM;
> - }
> + if (!free_nid_slab)
> + goto destory_nat_entry;
> +
> + nat_entry_set_slab = f2fs_kmem_cache_create("nat_entry_set",
> + sizeof(struct nat_entry_set));
> + if (!nat_entry_set_slab)
> + goto destory_free_nid;
> return 0;
> +
> +destory_free_nid:
> + kmem_cache_destroy(free_nid_slab);
> +destory_nat_entry:
> + kmem_cache_destroy(nat_entry_slab);
> +fail:
> + return -ENOMEM;
> }
>
> void destroy_node_manager_caches(void)
> {
> + kmem_cache_destroy(nat_entry_set_slab);
> kmem_cache_destroy(free_nid_slab);
> kmem_cache_destroy(nat_entry_slab);
> }
> diff --git a/fs/f2fs/node.h b/fs/f2fs/node.h
> index 7281112..8a116a4 100644
> --- a/fs/f2fs/node.h
> +++ b/fs/f2fs/node.h
> @@ -89,6 +89,13 @@ enum mem_type {
> DIRTY_DENTS /* indicates dirty dentry pages */
> };
>
> +struct nat_entry_set {
> + struct list_head set_list; /* link with all nat sets */
> + struct list_head entry_list; /* link with dirty nat entries */
> + nid_t start_nid; /* start nid of nats in set */
> + unsigned int entry_cnt; /* the # of nat entries in set */
> +};
> +
> /*
> * For free nid mangement
> */
> --
> 1.7.9.5
--
Jaegeuk Kim
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