[Haskell-cafe] Re: announcing darcs 2.0.0pre2

David Roundy droundy at darcs.net
Mon Dec 17 19:06:08 EST 2007

Thanks for the timings.  Alas, I'm leaving in the morning for vacation, so
I'm not sure when I'll have time to profile these operations.  And I'm
still puzzling over how to speed up darcs get (i.e. the long discussion of
http pipelining, which will not, of course, do anything to help the poor
folks stuck with ssh...).

The 100x slower pull is indeed a bit puzzling.  I can't help but wonder if
it's the hash-checking (but that seems very unlikely)...


On Mon, Dec 17, 2007 at 12:29:20PM +0000, Simon Marlow wrote:
> Continuing my performance tests, I tried unpulling and re-pulling a bunch 
> of patches in a GHC tree.  I'm unpulling about 400 patches using 
> --from-tag, and then pulling them again from a local repo.  Summary: darcs2 
> is about 10x slower than darcs1 on unpull, and on pull it is 100x slower in 
> user time but only 20x slower in elapsed time.
> In both cases, the repository was on an NFS filesystem.  In the darcs2 
> case, the repository I was pulling from was on the local disk, and I'm also 
> using a cache (NFS-mounted).  The darcs2 repository has been optimized, but 
> the darcs1 repository has not (at lesat, not recently).  I did all of these 
> a couple of times to eliminate the effects of cache preloading etc., the 
> times reported are from the second run.
> ------- darcs 1:
> $ time darcs unpull --from-tag 2007-09-25 -a
> Finished unpulling.
> 35.17s real   5.77s user   1.00s system   19% darcs unpull --from-tag 
> 2007-09-25 -a
> $ time darcs pull ~/ghc-HEAD -a
> Pulling from "/home/simonmar/ghc-HEAD"...
> 33.51s real   3.62s user   1.05s system   13% darcs pull ~/ghc-HEAD -a
> ------- darcs 2:
> $ time darcs2 unpull --from-tag 2007-09-25 -a
> Finished unpulling.
> 385.22s real   52.18s user   12.62s system   16% darcs2 unpull --from-tag 
> 2007-09-25 -a
> $ time darcs2 pull /64playpen/simonmar/ghc-darcs2 -a
> Finished pulling and applying.
> 668.75s real   290.74s user   15.03s system   45% darcs2 pull 
> /64playpen/simonmar/ghc-darcs2 -a

David Roundy
Department of Physics
Oregon State University

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