Re: [PATCH 0/3] avoid quadratic behavior in fetch-pack

From: Martin Fick <mfick@codeaurora.org>
Date: Jul 2, 2013, 17:45 UTC
Message-ID: <201307021145.07726.mfick@codeaurora.org>
In-Reply-To: <20130702061149.GB1206@sigill.intra.peff.net>

On Tuesday, July 02, 2013 12:11:49 am Jeff King wrote:

Show 21 quoted lines

> Here are my patches to deal with Martin's pathological
> case, split out for easy reading. I took a few timings
> to show that the results of the 3rd patch are noticeable
> even with 50,000 unique refs (which is still a lot, but
> something that I could conceive of a busy repo
> accumulating over time).
> 
>   [1/3]: fetch-pack: avoid quadratic list insertion in
> mark_complete [2/3]: commit.c: make
> compare_commits_by_commit_date global [3/3]: fetch-pack:
> avoid quadratic behavior in rev_list_push
> 
> And here's the diffstat to prove it is really not scary.
> :)
> 
>  commit.c     |  2 +-
>  commit.h     |  2 ++
>  fetch-pack.c | 16 ++++++++--------
>  3 files changed, 11 insertions(+), 9 deletions(-)
> 
> -Peff

I applied these 3 patches and it indeed improves things dramatically. Thanks Peff, you are awesome!!!

The synthetic test case (but sorted), now comes in at around 15s. The more important real world case (for us), fetching from my production server, which took around 12mins previously, now takes around 30s (I think the extra time is now spent on the Gerrit server, but I will investigate that a bit more)! That is very significant and should make many workflows much more efficient. +1 for merging this. :)

Again, thanks,

-Martin

Note, I tested git-next 1.8.3.2.883.g27cfd27 to be sure that it is still problematic without this patch, it is (running for 10mins now without completing).

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