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| author | Theodore Ts'o <tytso@mit.edu> | 2014-07-25 13:38:50 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2014-07-26 00:48:29 -0400 |
| commit | baab9f43bf0ecacd043dafb2de29163da5deaf24 (patch) | |
| tree | 84b3fda0ca5fcde7253da2d9afaacdaacaac5e9e /resize | |
| parent | 2dbf34e50562d08d5da4d3f373f3bc0b2fd46728 (diff) | |
| download | e2fsprogs-baab9f43bf0ecacd043dafb2de29163da5deaf24.tar.gz | |
resize2fs: radically reduce memory utilization by using rbtree bitmaps
When resizing an empty 21T file system to 28T, resize2fs was using
this much CPU time and memory:
216.98user 19.77system 4:02.92elapsed 97%CPU (0avgtext+0avgdata 4485664maxresident)k
8inputs+1068680outputs (0major+800745minor)pagefaults 0swaps
After this one-line change:
222.29user 0.49system 3:48.79elapsed 97%CPU (0avgtext+0avgdata 30080maxresident)k
8inputs+1068552outputs (0major+2497minor)pagefaults 0swaps
So this reduces the max memory utilized from 4.2GB to 29MB!
For future work, the primary place where we are spending the most cpu
time (from resize2fs -d 16) are these two places:
blocks_to_move: Memory used: 2508k/25096k (1903k/606k), time: 91.42/91.53/ 0.00
and
calculate_summary_stats: Memory used: 2508k/25612k (1908k/601k), time: 95.33/95.45/ 0.00
The calculate_summary_stats pass can be sped up by using
ext2fs_find_first_{zero,set}_block_bitmap2(), instead of iterating
over the entire block bitmap one bit at a time.
The blocks_to_move pass can be sped up by using a bitmap to store the
location of fs metadata blocks, to avoid an O(N**2) algorithm where N
is the number of groups in the file system.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'resize')
| -rw-r--r-- | resize/main.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/resize/main.c b/resize/main.c index e4b44354..ef2a810b 100644 --- a/resize/main.c +++ b/resize/main.c @@ -318,6 +318,7 @@ int main (int argc, char ** argv) printf("%s", _("Couldn't find valid filesystem superblock.\n")); exit (1); } + fs->default_bitmap_type = EXT2FS_BMAP64_RBTREE; if (!(mount_flags & EXT2_MF_MOUNTED)) { if (!force && ((fs->super->s_lastcheck < fs->super->s_mtime) || |