Version control systems

Manuel M T Chakravarty chak at cse.unsw.edu.au
Wed Aug 13 22:26:47 EDT 2008


Duncan Coutts:
> On Mon, 2008-08-11 at 13:57 +0100, Simon Marlow wrote:
>>  - Performance.  darcs2 regressed in performance for many  
>> operations we
>>    commonly use.  I've submitted some measurements for some things,  
>> but
>>    it's pretty easy to find your own test cases: things like "darcs  
>> add",
>>    "darcs whatsnew", "darcs unrecord" are all slower than darcs 1.   
>> When
>>    simple operations take multiple seconds to complete, it really  
>> slows
>>    down your workflow.
>
> Turns out that the reason for slow darcs whatsnew is ghc bug #2093
>
> http://hackage.haskell.org/trac/ghc/ticket/2093
>
> because getSymbolicLinkStatus is broken on 32bit systems in 6.8.2 it
> means that the 'stat' optimisation does not work so darcs has to read
> the actual contents of many files. Obviously that's very slow,
> especially over nfs. That explains why it worked for me in 0.2 seconds
> but for you took several seconds user time and (even more real time  
> due
> to nfs).

LOL - that is funny.  GHC devel slowed down by slow darcs due to GHC  
bug.

The bug is fixed, isn't it?  So, recompiling darcs with 6.8.3 should  
improve matters.

Manuel



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