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Message-ID: <PUZPR04MB6316A41FC40A84059E60BAB481399@PUZPR04MB6316.apcprd04.prod.outlook.com>
Date: Wed, 2 Nov 2022 07:11:23 +0000
From: "Yuezhang.Mo@...y.com" <Yuezhang.Mo@...y.com>
To: Namjae Jeon <linkinjeon@...nel.org>,
Sungjong Seo <sj1557.seo@...sung.com>
CC: linux-kernel <linux-kernel@...r.kernel.org>,
linux-fsdevel <linux-fsdevel@...r.kernel.org>,
"Andy.Wu@...y.com" <Andy.Wu@...y.com>,
"Wataru.Aoyama@...y.com" <Wataru.Aoyama@...y.com>
Subject: [PATCH v2 2/2] exfat: hint the empty entry which at the end of
cluster chain
After traversing all directory entries, hint the empty directory
entry no matter whether or not there are enough empty directory
entries.
After this commit, hint the empty directory entries like this:
1. Hint the deleted directory entries if enough;
2. Hint the deleted and unused directory entries which at the
end of the cluster chain no matter whether enough or not(Add
by this commit);
3. If no any empty directory entries, hint the empty directory
entries in the new cluster(Add by this commit).
This avoids repeated traversal of directory entries, reduces CPU
usage, and improves the performance of creating files and
directories(especially on low-performance CPUs).
Test create 5000 files in a class 4 SD card on imx6q-sabrelite
with:
for ((i=0;i<5;i++)); do
sync
time (for ((j=1;j<=1000;j++)); do touch file$((i*1000+j)); done)
done
The more files, the more performance improvements.
Before After Improvement
1~1000 25.360s 22.168s 14.40%
1001~2000 38.242s 28.72ss 33.15%
2001~3000 49.134s 35.037s 40.23%
3001~4000 62.042s 41.624s 49.05%
4001~5000 73.629s 46.772s 57.42%
Signed-off-by: Yuezhang Mo <Yuezhang.Mo@...y.com>
Reviewed-by: Andy Wu <Andy.Wu@...y.com>
Reviewed-by: Aoyama Wataru <wataru.aoyama@...y.com>
---
fs/exfat/dir.c | 26 ++++++++++++++++++++++----
fs/exfat/namei.c | 33 +++++++++++++++++++++------------
2 files changed, 43 insertions(+), 16 deletions(-)
diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c
index 9f9b8435baca..5497a610808d 100644
--- a/fs/exfat/dir.c
+++ b/fs/exfat/dir.c
@@ -905,17 +905,24 @@ static inline void exfat_reset_empty_hint(struct exfat_hint_femp *hint_femp)
static inline void exfat_set_empty_hint(struct exfat_inode_info *ei,
struct exfat_hint_femp *candi_empty, struct exfat_chain *clu,
- int dentry, int num_entries)
+ int dentry, int num_entries, int entry_type)
{
if (ei->hint_femp.eidx == EXFAT_HINT_NONE ||
ei->hint_femp.eidx > dentry) {
+ int total_entries = EXFAT_B_TO_DEN(i_size_read(&ei->vfs_inode));
+
if (candi_empty->count == 0) {
candi_empty->cur = *clu;
candi_empty->eidx = dentry;
}
- candi_empty->count++;
- if (candi_empty->count == num_entries)
+ if (entry_type == TYPE_UNUSED)
+ candi_empty->count += total_entries - dentry;
+ else
+ candi_empty->count++;
+
+ if (candi_empty->count == num_entries ||
+ candi_empty->count + candi_empty->eidx == total_entries)
ei->hint_femp = *candi_empty;
}
}
@@ -989,7 +996,8 @@ int exfat_find_dir_entry(struct super_block *sb, struct exfat_inode_info *ei,
step = DIRENT_STEP_FILE;
exfat_set_empty_hint(ei, &candi_empty, &clu,
- dentry, num_entries);
+ dentry, num_entries,
+ entry_type);
brelse(bh);
if (entry_type == TYPE_UNUSED)
@@ -1100,6 +1108,16 @@ int exfat_find_dir_entry(struct super_block *sb, struct exfat_inode_info *ei,
goto rewind;
}
+ /*
+ * set the EXFAT_EOF_CLUSTER flag to avoid search
+ * from the beginning again when allocated a new cluster
+ */
+ if (ei->hint_femp.eidx == EXFAT_HINT_NONE) {
+ ei->hint_femp.cur.dir = EXFAT_EOF_CLUSTER;
+ ei->hint_femp.eidx = p_dir->size * dentries_per_clu;
+ ei->hint_femp.count = 0;
+ }
+
/* initialized hint_stat */
hint_stat->clu = p_dir->dir;
hint_stat->eidx = 0;
diff --git a/fs/exfat/namei.c b/fs/exfat/namei.c
index b617bebc3d0f..add4893711d3 100644
--- a/fs/exfat/namei.c
+++ b/fs/exfat/namei.c
@@ -224,11 +224,18 @@ static int exfat_search_empty_slot(struct super_block *sb,
if (hint_femp->eidx != EXFAT_HINT_NONE) {
dentry = hint_femp->eidx;
- if (num_entries <= hint_femp->count) {
- hint_femp->eidx = EXFAT_HINT_NONE;
- return dentry;
- }
+ /*
+ * If hint_femp->count is enough, it is needed to check if
+ * there are actual empty entries.
+ * Otherwise, and if "dentry + hint_famp->count" is also equal
+ * to "p_dir->size * dentries_per_clu", it means ENOSPC.
+ */
+ if (dentry + hint_femp->count == p_dir->size * dentries_per_clu
+ && num_entries > hint_femp->count)
+ return -ENOSPC;
+
+ hint_femp->eidx = EXFAT_HINT_NONE;
exfat_chain_dup(&clu, &hint_femp->cur);
} else {
exfat_chain_dup(&clu, p_dir);
@@ -293,6 +300,12 @@ static int exfat_search_empty_slot(struct super_block *sb,
}
}
+ hint_femp->eidx = p_dir->size * dentries_per_clu - num_empty;
+ hint_femp->count = num_empty;
+ if (num_empty == 0)
+ exfat_chain_set(&hint_femp->cur, EXFAT_EOF_CLUSTER, 0,
+ clu.flags);
+
return -ENOSPC;
}
@@ -369,15 +382,11 @@ static int exfat_find_empty_entry(struct inode *inode,
if (exfat_ent_set(sb, last_clu, clu.dir))
return -EIO;
- if (hint_femp.eidx == EXFAT_HINT_NONE) {
- /* the special case that new dentry
- * should be allocated from the start of new cluster
- */
- hint_femp.eidx = EXFAT_B_TO_DEN_IDX(p_dir->size, sbi);
- hint_femp.count = sbi->dentries_per_clu;
-
+ if (hint_femp.cur.dir == EXFAT_EOF_CLUSTER)
exfat_chain_set(&hint_femp.cur, clu.dir, 0, clu.flags);
- }
+
+ hint_femp.count += sbi->dentries_per_clu;
+
hint_femp.cur.size++;
p_dir->size++;
size = EXFAT_CLU_TO_B(p_dir->size, sbi);
--
2.25.1
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