After running "gotadmin pack" on a FreeBSD src repository consisting
of all loose objects, I also ran "gotadmin cleanup":

4069139 loose objects; 377383 commits scanned; 4069109 objects purged
loose total size before: 14.8G
loose total size after: 24.9K
disk space freed: 14.8G
loose objects also found in pack files: 4068040

Wait, why are there 30 loose objects left?  It's not an accounting
error, they are there under objects/[0-9a-f][0-9a-f]/.  If they are
reachable, they should have been packed.  If they are unreachable,
"cleanup" should have also removed them.

(And why is the number of "loose objects also found in pack files"
still smaller?)

$ git fsck --unreachable
Checking object directories: 100% (256/256), done.
Checking objects: 100% (4069109/4069109), done.
Checking connectivity: 4069139, done.

-- 
Christian "naddy" Weisgerber                          naddy@mips.inka.de