On Wed, May 27, 2009 at 11:10:09AM -0300, Atila Romero
wrote:> During a file write, if the compression doesn''t proves to be
economical
> to a portion of the file, the whole file is marked as nocompress, and
> subsequent writes don''t use compression at all. This can be seen
as a
> feature, as it saves CPU in files like videos. But if the file is a dd
> image of a disk, or other types of large files, this behavior is
> undesirable, since different portions of the file will have different
> compression ratios.
> I only became aware of this after searching the source code, after
> spending some hours trying to find out why the compression wasn''t
> working. This can be a really unexpected behavior for a end user who is
> looking for compression.
> The specific part of the code is at inode.c:
> 477 <#l477>
> /* flag the file so we don''t compress in the
future */
> 478 <#l478> btrfs_set_flag(inode, NOCOMPRESS);
>
> How about commenting line 478?
The plan is to add a flag for the file to make it always compress even
when parts of the file do not compress well.
-chris
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs"
in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html