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| author | Zheng Liu <wenqing.lz@taobao.com> | 2012-08-17 09:54:17 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2012-08-17 09:54:17 -0400 |
| commit | 67a5da564f97f31c4054d358e00b34d7ee570da5 (patch) | |
| tree | 525f256d46cfac4be0b0acd90cc2bad5fcdb1b77 /fs/ext4/super.c | |
| parent | 81370291722ac1e0ec95234a0ea91a5bc76b6185 (diff) | |
| download | linux-67a5da564f97f31c4054d358e00b34d7ee570da5.tar.gz | |
ext4: make the zero-out chunk size tunable
Currently in ext4 the length of zero-out chunk is set to 7 file system blocks. But if an inode has uninitailized extents from using fallocate to preallocate space, and the workload issues many random writes, this can cause a fragmented extent tree that will unnecessarily grow the extent tree. So create a new sysfs tunable, extent_max_zeroout_kb, which controls the maximum size where blocks will be zeroed out instead of creating a new uninitialized extent. The default of this has been sent to 32kb. CC: Zach Brown <zab@zabbo.net> CC: Andreas Dilger <adilger@dilger.ca> Signed-off-by: Zheng Liu <wenqing.lz@taobao.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Diffstat (limited to 'fs/ext4/super.c')
| -rw-r--r-- | fs/ext4/super.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 5a97e590692d..0423e2e7f615 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -2541,6 +2541,7 @@ EXT4_RW_ATTR_SBI_UI(mb_order2_req, s_mb_order2_reqs); EXT4_RW_ATTR_SBI_UI(mb_stream_req, s_mb_stream_request); EXT4_RW_ATTR_SBI_UI(mb_group_prealloc, s_mb_group_prealloc); EXT4_RW_ATTR_SBI_UI(max_writeback_mb_bump, s_max_writeback_mb_bump); +EXT4_RW_ATTR_SBI_UI(extent_max_zeroout_kb, s_extent_max_zeroout_kb); EXT4_ATTR(trigger_fs_error, 0200, NULL, trigger_test_error); static struct attribute *ext4_attrs[] = { @@ -2556,6 +2557,7 @@ static struct attribute *ext4_attrs[] = { ATTR_LIST(mb_stream_req), ATTR_LIST(mb_group_prealloc), ATTR_LIST(max_writeback_mb_bump), + ATTR_LIST(extent_max_zeroout_kb), ATTR_LIST(trigger_fs_error), NULL, }; @@ -3756,6 +3758,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) sbi->s_stripe = ext4_get_stripe_size(sbi); sbi->s_max_writeback_mb_bump = 128; + sbi->s_extent_max_zeroout_kb = 32; /* * set up enough so that it can read an inode |