Hi,
> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaegeuk....@samsung.com]
> Sent: Friday, December 06, 2013 12:12 PM
> To: Chao Yu
> Cc: linux-fsde...@vger.kernel.org; linux-kernel@vger.kernel.org;
> linux-f2fs-de...@lists.sourceforge.net; 谭姝
> Subject: Re: [f2fs-dev] [PATCH 2/5 V2] f2fs: add unlikely() macro for
> compiler optimization
>
> Hi,
>
> Just in case, if you agreed the following comments, I'll fix those and
> merge the patch by myself.
> Thanks,
Agreed, thanks.
>
> 2013-12-05 (목), 17:15 +0800, Chao Yu:
> > As we know, some of our branch condition will rarely be true. So we could
> > add
> > 'unlikely' to let compiler optimize these code, by this way we could drop
> > unneeded 'jump' assemble code to improve performance.
> >
> > change log:
> > o add *unlikely* as many as possible across the whole source files at once
> > suggested by Jaegeuk Kim.
> >
> > Suggested-by: Jaegeuk Kim <jaegeuk....@samsung.com>
> > Signed-off-by: Chao Yu <chao2...@samsung.com>
> > ---
> > fs/f2fs/checkpoint.c | 10 +++++-----
> > fs/f2fs/data.c | 4 ++--
> > fs/f2fs/dir.c | 4 ++--
> > fs/f2fs/f2fs.h | 8 ++++----
> > fs/f2fs/node.c | 16 ++++++++--------
> > fs/f2fs/segment.h | 2 +-
> > 6 files changed, 22 insertions(+), 22 deletions(-)
> >
> > diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> > index 38f4a224..6580808 100644
> > --- a/fs/f2fs/checkpoint.c
> > +++ b/fs/f2fs/checkpoint.c
> > @@ -82,8 +82,8 @@ static int f2fs_write_meta_page(struct page *page,
> > struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
> >
> > /* Should not write any meta pages, if any IO error was occurred */
> > - if (wbc->for_reclaim || sbi->por_doing ||
> > - is_set_ckpt_flags(F2FS_CKPT(sbi), CP_ERROR_FLAG)) {
> > + if (unlikely(wbc->for_reclaim || sbi->por_doing ||
> > + is_set_ckpt_flags(F2FS_CKPT(sbi), CP_ERROR_FLAG))) {
>
> if (unlikely(sbi->por_doing || is_set_ckpt_flags(F2FS_CKPT(sbi),
> CP_ERROR_FLAG)))
> goto redirty_out;
> if (wbc->for_reclaim)
> goto redirty_out;
>
> redirty_out:
> > dec_page_count(sbi, F2FS_DIRTY_META);
> > wbc->pages_skipped++;
> > set_page_dirty(page);
> > @@ -137,7 +137,7 @@ long sync_meta_pages(struct f2fs_sb_info *sbi, enum
> > page_type type,
> > nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
> > PAGECACHE_TAG_DIRTY,
> > min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
> > - if (nr_pages == 0)
> > + if (unlikely(nr_pages == 0))
> > break;
> >
> > for (i = 0; i < nr_pages; i++) {
> > @@ -150,7 +150,7 @@ long sync_meta_pages(struct f2fs_sb_info *sbi, enum
> > page_type type,
> > unlock_page(page);
> > break;
> > }
> > - if (nwritten++ >= nr_to_write)
> > + if (unlikely(nwritten++ >= nr_to_write))
>
> nwritten++;
>
> if (unlikely(nwritten >= nr_to_write))
>
>
> > break;
> > }
> > pagevec_release(&pvec);
> > @@ -200,7 +200,7 @@ int acquire_orphan_inode(struct f2fs_sb_info *sbi)
> > max_orphans = (sbi->blocks_per_seg - 2 - NR_CURSEG_TYPE)
> > * F2FS_ORPHANS_PER_BLOCK;
> > mutex_lock(&sbi->orphan_inode_mutex);
> > - if (sbi->n_orphans >= max_orphans)
> > + if (unlikely(sbi->n_orphans >= max_orphans))
> > err = -ENOSPC;
> > else
> > sbi->n_orphans++;
> > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> > index 4e2fc09..2ce5a9e 100644
> > --- a/fs/f2fs/data.c
> > +++ b/fs/f2fs/data.c
> > @@ -251,7 +251,7 @@ int reserve_new_block(struct dnode_of_data *dn)
> >
> > if (is_inode_flag_set(F2FS_I(dn->inode), FI_NO_ALLOC))
> > return -EPERM;
> > - if (!inc_valid_block_count(sbi, dn->inode, 1))
> > + if (unlikely(!inc_valid_block_count(sbi, dn->inode, 1)))
> > return -ENOSPC;
> >
> > trace_f2fs_reserve_new_block(dn->inode, dn->nid, dn->ofs_in_node);
> > @@ -711,7 +711,7 @@ static int f2fs_write_data_page(struct page *page,
> >
> > zero_user_segment(page, offset, PAGE_CACHE_SIZE);
> > write:
> > - if (sbi->por_doing) {
> > + if (unlikely(sbi->por_doing)) {
> > err = AOP_WRITEPAGE_ACTIVATE;
> > goto redirty_out;
> > }
> > diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
> > index 594fc1b..0cc26ba 100644
> > --- a/fs/f2fs/dir.c
> > +++ b/fs/f2fs/dir.c
> > @@ -190,7 +190,7 @@ struct f2fs_dir_entry *f2fs_find_entry(struct inode
> > *dir,
> > unsigned int max_depth;
> > unsigned int level;
> >
> > - if (namelen > F2FS_NAME_LEN)
> > + if (unlikely(namelen > F2FS_NAME_LEN))
> > return NULL;
> >
> > if (npages == 0)
> > @@ -461,7 +461,7 @@ int __f2fs_add_link(struct inode *dir, const struct
> > qstr *name, struct inode *in
> > }
> >
> > start:
> > - if (current_depth == MAX_DIR_HASH_DEPTH)
> > + if (unlikely(current_depth == MAX_DIR_HASH_DEPTH))
> > return -ENOSPC;
> >
> > /* Increase the depth, if required */
> > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > index 10eca02..dca18b3 100644
> > --- a/fs/f2fs/f2fs.h
> > +++ b/fs/f2fs/f2fs.h
> > @@ -574,7 +574,7 @@ static inline void f2fs_unlock_all(struct f2fs_sb_info
> > *sbi)
> > static inline int check_nid_range(struct f2fs_sb_info *sbi, nid_t nid)
> > {
> > WARN_ON((nid >= NM_I(sbi)->max_nid));
> > - if (nid >= NM_I(sbi)->max_nid)
> > + if (unlikely(nid >= NM_I(sbi)->max_nid))
> > return -EINVAL;
> > return 0;
> > }
> > @@ -600,7 +600,7 @@ static inline bool inc_valid_block_count(struct
> > f2fs_sb_info *sbi,
> > spin_lock(&sbi->stat_lock);
> > valid_block_count =
> > sbi->total_valid_block_count + (block_t)count;
> > - if (valid_block_count > sbi->user_block_count) {
> > + if (unlikely(valid_block_count > sbi->user_block_count)) {
> > spin_unlock(&sbi->stat_lock);
> > return false;
> > }
> > @@ -719,13 +719,13 @@ static inline bool inc_valid_node_count(struct
> > f2fs_sb_info *sbi,
> > spin_lock(&sbi->stat_lock);
> >
> > valid_block_count = sbi->total_valid_block_count + 1;
> > - if (valid_block_count > sbi->user_block_count) {
> > + if (unlikely(valid_block_count > sbi->user_block_count)) {
> > spin_unlock(&sbi->stat_lock);
> > return false;
> > }
> >
> > valid_node_count = sbi->total_valid_node_count + 1;
> > - if (valid_node_count > sbi->total_node_count) {
> > + if (unlikely(valid_node_count > sbi->total_node_count)) {
> > spin_unlock(&sbi->stat_lock);
> > return false;
> > }
> > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> > index 5e2588f..48cbf76 100644
> > --- a/fs/f2fs/node.c
> > +++ b/fs/f2fs/node.c
> > @@ -94,7 +94,7 @@ static void ra_nat_pages(struct f2fs_sb_info *sbi, int
> > nid)
> > int i;
> >
> > for (i = 0; i < FREE_NID_PAGES; i++, nid += NAT_ENTRY_PER_BLOCK) {
> > - if (nid >= nm_i->max_nid)
> > + if (unlikely(nid >= nm_i->max_nid))
> > nid = 0;
> > index = current_nat_addr(sbi, nid);
> >
> > @@ -1160,7 +1160,7 @@ int wait_on_node_pages_writeback(struct f2fs_sb_info
> > *sbi, nid_t ino)
> > struct page *page = pvec.pages[i];
> >
> > /* until radix tree lookup accepts end_index */
> > - if (page->index > end)
> > + if (unlikely(page->index > end))
> > continue;
> >
> > if (ino && ino_of_node(page) == ino) {
> > @@ -1190,7 +1190,7 @@ static int f2fs_write_node_page(struct page *page,
> > block_t new_addr;
> > struct node_info ni;
> >
> > - if (sbi->por_doing)
> > + if (unlikely(sbi->por_doing))
> > goto redirty_out;
> >
> > wait_on_page_writeback(page);
> > @@ -1326,7 +1326,7 @@ static int add_free_nid(struct f2fs_nm_info *nm_i,
> > nid_t nid, bool build)
> > return -1;
> >
> > /* 0 nid should not be used */
> > - if (nid == 0)
> > + if (unlikely(nid == 0))
> > return 0;
> >
> > if (build) {
> > @@ -1379,7 +1379,7 @@ static void scan_nat_page(struct f2fs_nm_info *nm_i,
> >
> > for (; i < NAT_ENTRY_PER_BLOCK; i++, start_nid++) {
> >
> > - if (start_nid >= nm_i->max_nid)
> > + if (unlikely(start_nid >= nm_i->max_nid))
> > break;
> >
> > blk_addr = le32_to_cpu(nat_blk->entries[i].block_addr);
> > @@ -1413,7 +1413,7 @@ static void build_free_nids(struct f2fs_sb_info *sbi)
> > f2fs_put_page(page, 1);
> >
> > nid += (NAT_ENTRY_PER_BLOCK - (nid % NAT_ENTRY_PER_BLOCK));
> > - if (nid >= nm_i->max_nid)
> > + if (unlikely(nid >= nm_i->max_nid))
> > nid = 0;
> >
> > if (i++ == FREE_NID_PAGES)
> > @@ -1447,7 +1447,7 @@ bool alloc_nid(struct f2fs_sb_info *sbi, nid_t *nid)
> > struct free_nid *i = NULL;
> > struct list_head *this;
> > retry:
> > - if (sbi->total_valid_node_count + 1 >= nm_i->max_nid)
> > + if (unlikely(sbi->total_valid_node_count + 1 >= nm_i->max_nid))
> > return false;
> >
> > spin_lock(&nm_i->free_nid_list_lock);
> > @@ -1557,7 +1557,7 @@ int recover_inode_page(struct f2fs_sb_info *sbi,
> > struct page *page)
> > new_ni = old_ni;
> > new_ni.ino = ino;
> >
> > - if (!inc_valid_node_count(sbi, NULL))
> > + if (unlikely(!inc_valid_node_count(sbi, NULL)))
> > WARN_ON(1);
> > set_node_addr(sbi, &new_ni, NEW_ADDR);
> > inc_valid_inode_count(sbi);
> > diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> > index 26812fc..ea56376 100644
> > --- a/fs/f2fs/segment.h
> > +++ b/fs/f2fs/segment.h
> > @@ -457,7 +457,7 @@ static inline bool has_not_enough_free_secs(struct
> > f2fs_sb_info *sbi, int freed)
> > int node_secs = get_blocktype_secs(sbi, F2FS_DIRTY_NODES);
> > int dent_secs = get_blocktype_secs(sbi, F2FS_DIRTY_DENTS);
> >
> > - if (sbi->por_doing)
> > + if (unlikely(sbi->por_doing))
> > return false;
> >
> > return ((free_sections(sbi) + freed) <= (node_secs + 2 * dent_secs +
>
> --
> Jaegeuk Kim
> Samsung
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