Re: Things to do this week instead of arguing about mixers

[Eric Sandeen <sandeen redhat com>]

Michael Cronenworth wrote:
> -------- Original Message --------
> Subject: Things to do this week instead of arguing about mixers
> From: Eric Sandeen <sandeen redhat com>
> To: Development discussions related to Fedora Core 
> <fedora-devel-list redhat com>
> Date: 04/27/2009 02:10 PM
> 
>> Now that we have ext4 as the new default filesystem, it'd be nice if we
>> can get more applications to take advantage of some of the features.
>>
> 
> Filesystems should be transparent to programs 99% of the time in my 
> humble little opinion. If ext4 depends on having falloc() calls then 
> ext4 has a bug. File a bug on it.
> 
> XFS, btrfs, or any file system that's better than the extX series don't 
> seem to have issues with requiring this function call.

You're missing the point here, I think.

Try downloading a large (multi-gigabyte) torrent on ext4 or xfs or
btrfs; see what the resulting file layout looks like if your client does
not preallocate.  Now use a client that preallocates the space and try
again.  Calling fallocate() first for the full file size will help on
all these filesystems (well, TBH, I have not tested it on btrfs).

If there are well-defined interfaces to give hints to the filesystem
about the ultimate state of a file, it's a nice feature, not a bug.

Sure, filesystems should do the best they can in the absence of hints,
but performing well (or better) _with_ a hint is not indicative of a bug.

-Eric