On 7/3/2013 11:40 AM, Junio C Hamano wrote:
> Brandon Casey <drafnel@xxxxxxxxx> writes:
>
>> Right. For repos with few refs on either side, I don't think there
>> will be any measurable difference. When pushing a single ref to a
>> repo with a very large number of refs, we will see a very small net
>> loss for the time required to prepare the string list (which grows
>> linearly with the number of remote refs). After 2 or 3 refs, we
>> should see a net gain.
>>
>> So we're really just improving our worst case performance here.
>
> ... by penalizing the common case by how much? If it is not too
> much, then this obviously would be a good change.
For something the size of the git repo, 5 branches, and pushing with
matching refspecs, I can't measure any difference. The fastest time I
record with or without this patch is the same:
$ time git push -n
real 0m0.178s
user 0m0.020s
sys 0m0.008s
Ditto, when only pushing a single branch. Preparing the string list for
a repo with a "normal" number of refs has very little overhead.
When the remote side has very many refs, then there is a small penalty
when the local side is pushing very few refs. But still, the penalty is
small.
My measurements for pushing from a repo with a single local branch into
my 100000+ ref repo showed <10% hit and the numbers were in the tens of
milliseconds.
before after
real 0m0.525s 0m0.566s
user 0m0.243s 0m0.279s
sys 0m0.075s 0m0.099s
>> ... But, I don't see a down side to doing the lazy prepare in
>> the other loop too, and in fact, it looks like we may be able to avoid
>> building the string list when only explicit refspecs are used. So,
>> yeah, we should lazy build in both loops.
>
> OK, so will see a reroll sometime?
Yeah, I'll reroll.
-Brandon
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