resize2fs block_mover() flushes data after each extent and, curiously,
only if progress indicator is enabled, every inode_blocks_per_group
blocks.
This significantly affects performance, e.g. on a tested large
filesystem on top of MD-RAID6+LVM+dm-crypt these flush calls reduce the
operation rate from approx. 500MB/s to 5MB/s, causing extremely long
shrinking times for large size deltas (70TB in my case).
Since this step performs just plain data copying and does not e.g. save
any progress/checkpoint information or similar metadata, it seems like
this flushing is of very limited usefulness, especially when considering
the (in some cases) 100x performance impact.
Remove the mid-operation flushes and only flush after all blocks have
been moved.
Signed-off-by: Anssi Hannula <anssi.hannula@xxxxxx>
---
resize/resize2fs.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/resize/resize2fs.c b/resize/resize2fs.c
index 5eeb7d44..46540501 100644
--- a/resize/resize2fs.c
+++ b/resize/resize2fs.c
@@ -1863,7 +1863,6 @@ static errcode_t block_mover(ext2_resize_t rfs)
old_blk += c;
moved += c;
if (rfs->progress) {
- io_channel_flush(fs->io);
retval = (rfs->progress)(rfs,
E2_RSZ_BLOCK_RELOC_PASS,
moved, to_move);
@@ -1871,9 +1870,10 @@ static errcode_t block_mover(ext2_resize_t rfs)
goto errout;
}
} while (size > 0);
- io_channel_flush(fs->io);
}
+ io_channel_flush(fs->io);
+
errout:
if (badblock_list) {
if (!retval && bb_modified)
--
2.41.0
