Wang Shilong
2014-Jun-20 11:09 UTC
[PATCH] Btrfs-progs: fsck: reduce memory usage for extents check
Steps to reproduce:
# mkfs.btrfs -f /dev/sda9 -b 2g
# mount /dev/sda9 /mnt
# dd if=/dev/zero of=/mnt/data bs=4k oflag=direct
# btrfs file df /mnt
Data, single: total=1.66GiB, used=1.66GiB
System, single: total=4.00MiB, used=16.00KiB
Metadata, single: total=200.00MiB, used=67.88MiB
For a filesystem without snapshots, 70M metadata, extent
checking eats max memory about 110M, this is a nightmare
for some system with low memory.
It is very likely that extent record can be freed quickly
for a filesystem without snapshots, improve this by trying
if it can free memory after adding data/tree backrefs.
This patch reduces max memory cost from 110M to 40M for
extents checking for the above case.
Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
---
cmds-check.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/cmds-check.c b/cmds-check.c
index 26baab0..ac97e48 100644
--- a/cmds-check.c
+++ b/cmds-check.c
@@ -2980,6 +2980,7 @@ static int add_tree_backref(struct cache_tree
*extent_cache, u64 bytenr,
}
back->node.found_extent_tree = 1;
}
+ maybe_free_extent_rec(extent_cache, rec);
return 0;
}
@@ -3046,6 +3047,7 @@ static int add_data_backref(struct cache_tree
*extent_cache, u64 bytenr,
back->num_refs = num_refs;
back->node.found_extent_tree = 1;
}
+ maybe_free_extent_rec(extent_cache, rec);
return 0;
}
--
1.9.0
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