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Date: Thu, 10 Feb 2011 15:33:26 +0800
From: Tao Ma <tm@....ma>
To: linux-ext4@...r.kernel.org
Cc: Andreas Dilger <adilger.kernel@...ger.ca>,
Lukas Czerner <lczerner@...hat.com>
Subject: [PATCH 4/4 v2] ext4: Speed up FITRIM by recording flags in ext4_group_info.
From: Tao Ma <boyu.mt@...bao.com>
In ext4, when FITRIM is called every time, we iterate all the
groups and do trim one by one. It is a bit time wasting if the
group has been trimmed and there is no change since the last
trim.
So this patch adds a new flag in ext4_group_info->bb_state to
indicate that the group has been trimmed, and it will be cleared
if some blocks is freed(in release_blocks_on_commit). Another
trim_minlen is added in ext4_sb_info to record the last minlen
we use to trim the volume, so that if the caller provide a small
one, we will go on the trim regardless of the bb_state.
A simple test with my intel x25m ssd:
df -h shows:
/dev/sdb2 108G 35G 68G 34% /mnt/ext4
Block size: 4096
run the FITRIM with the following parameter:
range.start = 0;
range.len = UINT64_MAX;
range.minlen = 1048576;
without the patch:
[root@...u-tm test]# time ./ftrim /mnt/ext4/a
real 0m4.039s
user 0m0.000s
sys 0m1.020s
[root@...u-tm test]# time ./ftrim /mnt/ext4/a
real 0m3.577s
user 0m0.001s
sys 0m1.004s
[root@...u-tm test]# time ./ftrim /mnt/ext4/a
real 0m3.380s
user 0m0.000s
sys 0m0.991s
with the patch:
[root@...u-tm test]# time ./ftrim /mnt/ext4/a
real 0m3.466s
user 0m0.000s
sys 0m0.966s
[root@...u-tm test]# time ./ftrim /mnt/ext4/a
real 0m0.001s
user 0m0.000s
sys 0m0.001s
[root@...u-tm test]# time ./ftrim /mnt/ext4/a
real 0m0.001s
user 0m0.000s
sys 0m0.000s
A big improvement for the 2nd and 3rd run.
After I delete some big image files and re-run the trim,
it is still much faster than iterating the whole disk.
/dev/sdb2 108G 25G 78G 24% /mnt/ext4
[root@...u-tm test]# time ./ftrim /mnt/ext4/a
real 0m0.513s
user 0m0.000s
sys 0m0.069s
Cc: Andreas Dilger <adilger.kernel@...ger.ca>
Cc: Lukas Czerner <lczerner@...hat.com>
Signed-off-by: Tao Ma <boyu.mt@...bao.com>
---
fs/ext4/ext4.h | 8 +++++++-
fs/ext4/mballoc.c | 22 ++++++++++++++++++++++
2 files changed, 29 insertions(+), 1 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 0c8d97b..1d59a63 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1200,6 +1200,9 @@ struct ext4_sb_info {
struct ext4_li_request *s_li_request;
/* Wait multiplier for lazy initialization thread */
unsigned int s_li_wait_mult;
+
+ /* record the last minlen when FITRIM is called. */
+ u64 s_last_trim_minblks;
};
static inline struct ext4_sb_info *EXT4_SB(struct super_block *sb)
@@ -1970,10 +1973,13 @@ struct ext4_group_info {
* 5 free 8-block regions. */
};
-#define EXT4_GROUP_INFO_NEED_INIT_BIT 0
+#define EXT4_GROUP_INFO_NEED_INIT_BIT 0
+#define EXT4_GROUP_INFO_WAS_TRIMMED_BIT 1
#define EXT4_MB_GRP_NEED_INIT(grp) \
(test_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &((grp)->bb_state)))
+#define EXT4_MB_GRP_HAS_BEEN_TRIMMED(grp) \
+ (test_bit(EXT4_GROUP_INFO_WAS_TRIMMED_BIT, &((grp)->bb_state)))
#define EXT4_MAX_CONTENTION 8
#define EXT4_CONTENTION_THRESHOLD 2
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 4eadac8..c7aa094 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2687,6 +2687,16 @@ static void release_blocks_on_commit(journal_t *journal, transaction_t *txn)
rb_erase(&entry->node, &(db->bb_free_root));
mb_free_blocks(NULL, &e4b, entry->start_blk, entry->count);
+ /*
+ * Clear the trimmed flag for the group so that the next
+ * ext4_trim_fs can trim it.
+ * If the volume is mounted with -o discard, online discard
+ * is supported and the free blocks will be trimmed online.
+ */
+ if (!test_opt(sb, DISCARD))
+ clear_bit(EXT4_GROUP_INFO_WAS_TRIMMED_BIT,
+ &(db->bb_state));
+
if (!db->bb_free_root.rb_node) {
/* No more items in the per group rb tree
* balance refcounts from ext4_mb_free_metadata()
@@ -4772,6 +4782,10 @@ ext4_grpblk_t ext4_trim_all_free(struct super_block *sb, struct ext4_buddy *e4b,
ext4_lock_group(sb, group);
+ if (EXT4_MB_GRP_HAS_BEEN_TRIMMED(e4b->bd_info) &&
+ minblocks >= EXT4_SB(sb)->s_last_trim_minblks)
+ goto out;
+
trace_ext4_trim_all_free(sb, group, start, max);
while (start < max) {
@@ -4804,6 +4818,11 @@ ext4_grpblk_t ext4_trim_all_free(struct super_block *sb, struct ext4_buddy *e4b,
if ((e4b->bd_info->bb_free - free_count) < minblocks)
break;
}
+
+ if (!ret)
+ set_bit(EXT4_GROUP_INFO_WAS_TRIMMED_BIT,
+ &(e4b->bd_info->bb_state));
+out:
ext4_unlock_group(sb, group);
ext4_debug("trimmed %d blocks in the group %d\n",
@@ -4892,6 +4911,9 @@ int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range)
}
range->len = trimmed * sb->s_blocksize;
+ if (!ret)
+ EXT4_SB(sb)->s_last_trim_minblks = minlen;
+
out:
return ret;
}
--
1.6.3.GIT
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