Re: What's in git.git

From: Junio C Hamano <junkio@cox.net>
Date: Feb 20, 2006, 09:04 UTC
Message-ID: <7vwtfqcsef.fsf@assigned-by-dhcp.cox.net>
In-Reply-To: <43F97F0D.9080500@op5.se>

Andreas Ericsson <ae@op5.se> writes:

Show 15 quoted lines

> Junio C Hamano wrote:
>
>> There now is further performance improvements for git-send-pack
>> to avoid sending a huge blob or tree object in its full
>> representation when we know the other end has a suitable object
>> to use as the base; instead we can just send it out deltified.
>> The other end would expand it to a loose object and this would
>> not make abit of difference in the resulting repository -- only
>> the bandwidth requirement reduction is visible [*1*].
>
> How likely is this to increase the CPU-power needed on the
> server-side? If there is a blob on the server-side, but far from the
> deltified object I suppose we have to look at each commit, perhaps
> only to discover that the client doesn't have them and we need to
> construct the blob anyways.

Not much. It deliberately keeps the set of blobs and trees to consider for remote base to minimum -- just the trees contained in the boundary commits. That way we may miss the best base candidate that are further back in history, but it does not matter because even using the less optimum one as a base saves us from sending the base object at all.