ldiskfs/kernel_patches/patches/sles11sp2/ext4-speed-up-fitrim-by-recording-flags-in-ext4_group_info.patch

   1 From 3d56b8d2c74cc3f375ce332b3ac3519e009d79ee Mon Sep 17 00:00:00 2001
   2 From: Tao Ma <boyu.mt@taobao.com>
   3 Date: Mon, 11 Jul 2011 00:03:38 -0400
   4 Subject: ext4: Speed up FITRIM by recording flags in ext4_group_info
   5 Git-commit: 3d56b8d2
   6 Patch-mainline: v3.1-rc1
   7
   8 In ext4, when FITRIM is called every time, we iterate all the
   9 groups and do trim one by one. It is a bit time wasting if the
  10 group has been trimmed and there is no change since the last
  11 trim.
  12
  13 So this patch adds a new flag in ext4_group_info->bb_state to
  14 indicate that the group has been trimmed, and it will be cleared
  15 if some blocks is freed(in release_blocks_on_commit). Another
  16 trim_minlen is added in ext4_sb_info to record the last minlen
  17 we use to trim the volume, so that if the caller provide a small
  18 one, we will go on the trim regardless of the bb_state.
  19
  20 A simple test with my intel x25m ssd:
  21 df -h shows:
  22 /dev/sdb1              40G   21G   17G  56% /mnt/ext4
  23 Block size:               4096
  24
  25 run the FITRIM with the following parameter:
  26 range.start = 0;
  27 range.len = UINT64_MAX;
  28 range.minlen = 1048576;
  29
  30 without the patch:
  31 [root@boyu-tm linux-2.6]# time ./ftrim /mnt/ext4/a
  32 real    0m5.505s
  33 user    0m0.000s
  34 sys     0m1.224s
  35 [root@boyu-tm linux-2.6]# time ./ftrim /mnt/ext4/a
  36 real    0m5.359s
  37 user    0m0.000s
  38 sys     0m1.178s
  39 [root@boyu-tm linux-2.6]# time ./ftrim /mnt/ext4/a
  40 real    0m5.228s
  41 user    0m0.000s
  42 sys     0m1.151s
  43
  44 with the patch:
  45 [root@boyu-tm linux-2.6]# time ./ftrim /mnt/ext4/a
  46 real    0m5.625s
  47 user    0m0.000s
  48 sys     0m1.269s
  49 [root@boyu-tm linux-2.6]# time ./ftrim /mnt/ext4/a
  50 real    0m0.002s
  51 user    0m0.000s
  52 sys     0m0.001s
  53 [root@boyu-tm linux-2.6]# time ./ftrim /mnt/ext4/a
  54 real    0m0.002s
  55 user    0m0.000s
  56 sys     0m0.001s
  57
  58 A big improvement for the 2nd and 3rd run.
  59
  60 Even after I delete some big image files, it is still much
  61 faster than iterating the whole disk.
  62
  63 [root@boyu-tm test]# time ./ftrim /mnt/ext4/a
  64 real    0m1.217s
  65 user    0m0.000s
  66 sys     0m0.196s
  67
  68 Upstream-Cc: Lukas Czerner <lczerner@redhat.com>
  69 Upstream-Reviewed-by: Andreas Dilger <adilger.kernel@dilger.ca>
  70 Upstream-Signed-off-by: Tao Ma <boyu.mt@taobao.com>
  71 Upstream-Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
  72 Signed-off-by: Jeff Mahoney <jeffm@suse.com>
  73 ---
  74  fs/ext4/ext4.h    |   13 ++++++++++++-
  75  fs/ext4/mballoc.c |   20 ++++++++++++++++++++
  76  2 files changed, 32 insertions(+), 1 deletion(-)
  77
  78 --- a/fs/ext4/ext4.h
  79 +++ b/fs/ext4/ext4.h
  80 @@ -1215,6 +1215,9 @@ struct ext4_sb_info {
  81
  82         /* Kernel thread for multiple mount protection */
  83         struct task_struct *s_mmp_tsk;
  84 +
  85 +       /* record the last minlen when FITRIM is called. */
  86 +       atomic_t s_last_trim_minblks;
  87  };
  88
  89  static inline struct ext4_sb_info *EXT4_SB(struct super_block *sb)
  90 @@ -2071,11 +2074,19 @@ struct ext4_group_info {
  91                                          * 5 free 8-block regions. */
  92  };
  93
  94 -#define EXT4_GROUP_INFO_NEED_INIT_BIT  0
  95 +#define EXT4_GROUP_INFO_NEED_INIT_BIT          0
  96 +#define EXT4_GROUP_INFO_WAS_TRIMMED_BIT                1
  97
  98  #define EXT4_MB_GRP_NEED_INIT(grp)     \
  99         (test_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &((grp)->bb_state)))
 100
 101 +#define EXT4_MB_GRP_WAS_TRIMMED(grp)   \
 102 +       (test_bit(EXT4_GROUP_INFO_WAS_TRIMMED_BIT, &((grp)->bb_state)))
 103 +#define EXT4_MB_GRP_SET_TRIMMED(grp)   \
 104 +       (set_bit(EXT4_GROUP_INFO_WAS_TRIMMED_BIT, &((grp)->bb_state)))
 105 +#define EXT4_MB_GRP_CLEAR_TRIMMED(grp) \
 106 +       (clear_bit(EXT4_GROUP_INFO_WAS_TRIMMED_BIT, &((grp)->bb_state)))
 107 +
 108  #define EXT4_MAX_CONTENTION            8
 109  #define EXT4_CONTENTION_THRESHOLD      2
 110
 111 --- a/fs/ext4/mballoc.c
 112 +++ b/fs/ext4/mballoc.c
 113 @@ -2629,6 +2629,15 @@ static void release_blocks_on_commit(jou
 114                 rb_erase(&entry->node, &(db->bb_free_root));
 115                 mb_free_blocks(NULL, &e4b, entry->start_blk, entry->count);
 116
 117 +               /*
 118 +                * Clear the trimmed flag for the group so that the next
 119 +                * ext4_trim_fs can trim it.
 120 +                * If the volume is mounted with -o discard, online discard
 121 +                * is supported and the free blocks will be trimmed online.
 122 +                */
 123 +               if (!test_opt(sb, DISCARD))
 124 +                       EXT4_MB_GRP_CLEAR_TRIMMED(db);
 125 +
 126                 if (!db->bb_free_root.rb_node) {
 127                         /* No more items in the per group rb tree
 128                          * balance refcounts from ext4_mb_free_metadata()
 129 @@ -4838,6 +4847,10 @@ ext4_trim_all_free(struct super_block *s
 130         bitmap = e4b.bd_bitmap;
 131
 132         ext4_lock_group(sb, group);
 133 +       if (EXT4_MB_GRP_WAS_TRIMMED(e4b.bd_info) &&
 134 +           minblocks >= atomic_read(&EXT4_SB(sb)->s_last_trim_minblks))
 135 +               goto out;
 136 +
 137         start = (e4b.bd_info->bb_first_free > start) ?
 138                 e4b.bd_info->bb_first_free : start;
 139
 140 @@ -4868,6 +4881,10 @@ ext4_trim_all_free(struct super_block *s
 141                 if ((e4b.bd_info->bb_free - count) < minblocks)
 142                         break;
 143         }
 144 +
 145 +       if (!ret)
 146 +               EXT4_MB_GRP_SET_TRIMMED(e4b.bd_info);
 147 +out:
 148         ext4_unlock_group(sb, group);
 149         ext4_mb_unload_buddy(&e4b);
 150
 151 @@ -4954,5 +4971,8 @@ int ext4_trim_fs(struct super_block *sb,
 152         }
 153         range->len = trimmed * sb->s_blocksize;
 154
 155 +       if (!ret)
 156 +               atomic_set(&EXT4_SB(sb)->s_last_trim_minblks, minlen);
 157 +
 158         return ret;
 159  }