default file system, was: Comparison to Workstation Technical Specification

[Eric Sandeen]

On 3/4/14, 3:43 PM, Ric Wheeler wrote:
> On 03/04/2014 11:26 PM, Przemek Klosowski wrote:
>> On 02/28/2014 03:45 PM, Adam Williamson wrote:
>>> As a server WG member I voted +1 on XFS as I have no particular objection to XFS as a filesystem, but I do think it seems a bit sub-optimal for us to wind up with server and desktop having defaults that are very similar but slightly different, for no apparently great reason.
>> This may be a historical bias. XFS is a large code base (*), which means two things: a larger bug surface, and a larger memory footprint that used to be a problem for personal desktop-type machines but less so for better endowed servers.
>>
>> I understand that by now XFS got so much exercise that its
>> robustness is unimpeachable. As to the size, I see that while the
>> latest XFS kernel module is one of the larger kernel modules
>> around, it probably is no longer significant on today's multi-GB
>> systems---the extra megabyte at current memory prices is just a one
>> cent increase in the system cost, after all.
>> 
>> Having said that, I don't use XFS nowadays so I don't know how much
>> more memory it allocates in typical use---can anyone comment on the
>> actual memory footprint of running XFS?
>> 
>> I am pretty sure that ext4 is a built-in module in Fedora kernels,
>> as well as in the boot environment; making XFS the default will
>> require also building it in, pretty much forever, while we still
>> need extXX, and whatever comes next (btrfs?). I am OK with that,
>> though.>>
>>
>> (*) 2.9MB of XFS source code vs 1.3MB in ext4 dirs
>> (**) xfs.ko is 1.3MB
>>
>>
> 
> You need to count the jbd2 code for ext4 as well,
> 
> Ric
> 

FWIW, I we looked at lines of code vs. megabytes of source, back in 3.4, and did a blog post about the trend lines:

http://sandeen.net/wordpress/computers/linux-filesystems-loc-update/

I did count jbd2 in that, as well as the "common" mbcache code which in truth is only used for the extN filesystems.

I suppose I need to do another update :)

-Eric