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Btrfs: lower the bar for chunk allocation

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The chunk allocation code has tried to keep a pretty tight lid on creating new
metadata chunks.  This is partially because in the past the reservation
code didn't give us an accurate idea of how much space was being used.

The new code is much more accurate, so we're able to get rid of some of these
checks.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason 2012-01-06 15:41:34 -05:00
parent 203bf287cb
commit cf1d72c9ce
1 changed files with 3 additions and 18 deletions
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21
fs/btrfs/extent-tree.c
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@ -3263,27 +3263,12 @@ static int should_alloc_chunk(struct btrfs_root *root,
if (num_bytes - num_allocated < thresh)
return 1;
}
/*
* we have two similar checks here, one based on percentage
* and once based on a hard number of 256MB. The idea
* is that if we have a good amount of free
* room, don't allocate a chunk. A good mount is
* less than 80% utilized of the chunks we have allocated,
* or more than 256MB free
*/
if (num_allocated + alloc_bytes + 256 * 1024 * 1024 < num_bytes)
return 0;
if (num_allocated + alloc_bytes < div_factor(num_bytes, 8))
return 0;
thresh = btrfs_super_total_bytes(root->fs_info->super_copy);
/* 256MB or 5% of the FS */
thresh = max_t(u64, 256 * 1024 * 1024, div_factor_fine(thresh, 5));
/* 256MB or 2% of the FS */
thresh = max_t(u64, 256 * 1024 * 1024, div_factor_fine(thresh, 2));
if (num_bytes > thresh && sinfo->bytes_used < div_factor(num_bytes, 3))
if (num_bytes > thresh && sinfo->bytes_used < div_factor(num_bytes, 8))
return 0;
return 1;
}