Re: Git and GCC

[Linus Torvalds <torvalds at linux-foundation dot org>]

On Wed, 5 Dec 2007, Harvey Harrison wrote:
> 
> If anyone recalls my report was something along the lines of
> git gc --aggressive explodes pack size.

Yes, --aggressive is generally a bad idea. I think we should remove it or 
at least fix it. It doesn't do what the name implies, because it actually 
throws away potentially good packing, and re-does it all from a clean 
slate.

That said, it's totally pointless for a person who isn't a git proponent 
to do an initial import, and in that sense I agree with Daniel: he 
shouldn't waste his time with tools that he doesn't know or care about, 
since there are people who *can* do a better job, and who know what they 
are doing, and understand and like the tool.

While you can do a half-assed job with just mindlessly running "git 
svnimport" (which is deprecated these days) or "git svn clone" (better), 
the fact is, to do a *good* import does likely mean spending some effort 
on it. Trying to make the user names / emails to be better with a mailmap, 
for example. 

[ By default, for example, "git svn clone/fetch" seems to create those 
  horrible fake email addresses that contain the ID of the SVN repo in 
  each commit - I'm not talking about the "git-svn-id", I'm talking about 
  the "user@hex-string-goes-here" thing for the author. Maybe people don't 
  really care, but isn't that ugly as hell? I'd think it's worth it doing 
  a really nice import, spending some effort on it.

  But maybe those things come from the older CVS->SVN import, I don't 
  really know. I've done a few SVN imports, but I've done them just for 
  stuff where I didn't want to touch SVN, but just wanted to track some 
  project like libgpod. For things like *that*, a totally mindless "git 
  svn" thing is fine ]

Of course, that does require there to be git people in the gcc crowd who 
are motivated enough to do the proper import and then make sure it's 
up-to-date and hosted somewhere. If those people don't exist, I'm not sure 
there's much idea to it.

The point being, you cannot ask a non-git person to do a major git import 
for an actual switch-over. Yes, it *can* be as simple as just doing a

	git svn clone --stdlayout svn://svn://gcc.gnu.org/svn/gcc gcc

but the fact remains, you want to spend more effort and expertise on it if 
you actually want the result to be used as a basis for future work (as 
opposed to just tracking somebody elses SVN tree).

That includes:

 - do the historic import with good packing (and no, "--aggressive" 
   is not it, never mind the misleading name and man-page)

 - probably mailmap entries, certainly spending some time validating the 
   results.

 - hosting it

and perhaps most importantly

 - helping people who are *not* git users get up to speed.

because doing a good job at it is like asking a CVS newbie to set up a 
branch in CVS. I'm sure you can do it from man-pages, but I'm also sure 
you sure as hell won't like the end result.

		Linus