Re: warning: no common commits - slow pull

[Junio C Hamano <gitster@pobox.com>]

Theodore Tso <tytso@MIT.EDU> writes:

> On Sun, Feb 10, 2008 at 08:07:38PM -0500, Len Brown wrote:
>> A couple of hours ago I pulled my reference copy of Linux tree,
>> which brought the tip here:
>> 
>> commit 7cf712db6087342e5e7e259d3883a7b5ac3212d1
>> Merge: 58a14ee... 30ddb15...
>> Author: Linus Torvalds <torvalds@woody.linux-foundation.org>
>> Date:   Sun Feb 10 12:03:57 2008 -0800
>> 
>>     Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6
>> 
>> Then, 10 minutes ago I did a pull to bring the head here:
>> 
>> commit 19af35546de68c872dcb687613e0902a602cb20e
>> Author: Linus Torvalds <torvalds@woody.linux-foundation.org>
>> Date:   Sun Feb 10 14:18:14 2008 -0800
>> 
>>     Linux 2.6.25-rc1
>> 
>> But this second pull seems to have re-downloaded 172MB,
>> when it should have only needed the last few commits.
>
> Yeah, I have this problem very often when I push to the ext4 tree on
> master.kernel.org.  Apparently the push/pull logic isn't smart about
> objects are found via objects/info/alterntaes, so it will needlessly
> transfer objects that it doesn't need to.

I am aware of that "push" side thing (basically it does not do
the negotiation and unless you are always doing fast-forward
pushes it tends to send needless stuff), but I had an impression
that the issue Len is raising is different.  Namely if you pull
from Linus twice into the same tree you should never see that
"No common commits".