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| author | Aditya Kali <adityakali@google.com> | 2012-07-01 03:10:57 +0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2012-07-01 03:10:57 +0400 |
| commit | 1c8457cadc9cefe7ec920a2f3537ff1fe20f4061 (patch) | |
| tree | 432621e536d959468f6206b8001a6023e9306fe7 /fs/ext4 | |
| parent | 6887a4131da3adaab011613776d865f4bcfb5678 (diff) | |
| download | linux-1c8457cadc9cefe7ec920a2f3537ff1fe20f4061.tar.xz | |
ext4: avoid uneeded calls to ext4_mb_load_buddy() while reading mb_groups
Currently ext4_mb_load_buddy is called for every group, irrespective
of whether the group info is already in memory, while reading
/proc/fs/ext4/<partition>/mb_groups proc file. For the purpose of
mb_groups proc file, it is unnecessary to load the file group info
from disk if it was loaded in past. These calls to ext4_mb_load_buddy
make reading the mb_groups proc file expensive.
Also, the locks around ext4_get_group_info are not required.
This patch modifies the code to call ext4_mb_load_buddy only if the
group info had never been loaded into memory in past. It also removes
the mb group locking around ext4_get_group_info call.
Signed-off-by: Aditya Kali <adityakali@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Diffstat (limited to 'fs/ext4')
| -rw-r--r-- | fs/ext4/mballoc.c | 23 |
1 files changed, 15 insertions, 8 deletions
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 1cd6994fc446..9f1e655979b9 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -2077,8 +2077,9 @@ static int ext4_mb_seq_groups_show(struct seq_file *seq, void *v) struct super_block *sb = seq->private; ext4_group_t group = (ext4_group_t) ((unsigned long) v); int i; - int err; + int err, buddy_loaded = 0; struct ext4_buddy e4b; + struct ext4_group_info *grinfo; struct sg { struct ext4_group_info info; ext4_grpblk_t counters[16]; @@ -2095,15 +2096,21 @@ static int ext4_mb_seq_groups_show(struct seq_file *seq, void *v) i = (sb->s_blocksize_bits + 2) * sizeof(sg.info.bb_counters[0]) + sizeof(struct ext4_group_info); - err = ext4_mb_load_buddy(sb, group, &e4b); - if (err) { - seq_printf(seq, "#%-5u: I/O error\n", group); - return 0; + grinfo = ext4_get_group_info(sb, group); + /* Load the group info in memory only if not already loaded. */ + if (unlikely(EXT4_MB_GRP_NEED_INIT(grinfo))) { + err = ext4_mb_load_buddy(sb, group, &e4b); + if (err) { + seq_printf(seq, "#%-5u: I/O error\n", group); + return 0; + } + buddy_loaded = 1; } - ext4_lock_group(sb, group); + memcpy(&sg, ext4_get_group_info(sb, group), i); - ext4_unlock_group(sb, group); - ext4_mb_unload_buddy(&e4b); + + if (buddy_loaded) + ext4_mb_unload_buddy(&e4b); seq_printf(seq, "#%-5u: %-5u %-5u %-5u [", group, sg.info.bb_free, sg.info.bb_fragments, sg.info.bb_first_free); |