Use of xz instead of gzip

[Stephen Montgomery-Smith]

On 08/10/2011 12:24 AM, Peter Jeremy wrote:
> On 2011-Aug-10 11:06:07 +0800, Stephen Montgomery-Smith<stephen at missouri.edu>  wrote:
>> It seems that xz has much better compression than gzip.  How do people
>> feel about moving CTM to use xz instead of gzip?
>
> Seems like a reasonable idea except for the 7.x issues.  Have you
> considered bzip2?

I created a .0001 delta for svn.  It is about 5G.  When compressed with 
gzip, it goes down to 1.8G.  When compressed with bzip2, it goes down to 
1.4G.  When compressed with xz, it goes down to 1G.  These are some huge 
differences in my opinion.

>> First, the attached patch needs to be applied to /usr/src.  (Any
>> committers willing to commit it?  It needs to MFC'ed rather quickly if I
>> start using xz.)
>
> You're unlikely to find any here apart from yourself.

I am merely a ports committer.  And now that I have been in this 
"exclusive club" for a few weeks, it bestows far less power and romance 
than an outsider might imagine.

>> Secondly, if your version of FreeBSD is old (like 7.x or older) you need
>> to install the archivers/xz port.  If you don't, when you attempt to
>> apply ctm to a "xz" compressed file, it replies with a rather helpful
>> message "xz not found."
>
> I can see this presenting a problem on 7.x (and earlier, but they are
> no longer supported) because the base system shouldn't have dependencies
> on ports.  The options would seem to be:
> 1) Stick with gzip for 7-src and earlier (as well as ports until 7.x
>     goes EOL)

By far most of CTM space is taken by the cvs-cur xEmpty files.  And 
these are agnostic to which version of FreeBSD is being used.

Stephen