[parsec-users] Fluidanimate double buffering bug

Elliott Slaughter slaughter at cs.stanford.edu
Thu Mar 15 23:56:32 EDT 2012


That said, my coworkers have suggested that this is a feature rather than a
bug. If so, please ignore the noise.

On Thu, Mar 15, 2012 at 6:53 PM, Elliott Slaughter <
slaughter at cs.stanford.edu> wrote:

> I believe I have found a bug in Parsec 2.1's fluidanimate benchmark.
> Specifically, nowhere in fluidanimate are pointers swapped for double
> buffering. This can be demonstrated by running fluidanimate for 1 step and
> for 2 steps and showing that the result files are identical. I have created
> a script which does exactly that (attached). The output is copied below.
>
> Thanks.
>
> ====================================================================
>
> We ran fluidanimate 3 times:
>   in_5k.fluid --> out1.fluid --> out2.fluid  (one step each time)
>   in_5k.fluid -----------------> out2b.fluid (two steps at once)
>
> Comparing out2.fluid and out2b.fluid...
> Note: These ought to match, but they don't.
>
> Tolerance: 1e-05
> 0: Values differ (-0.055712 vs. -0.0564135).
>
> Comparing out1.fluid and out2b.fluid...
> Note: These shouldn't match, but they do.
>
> Tolerance: 1e-05
> Files match.
>
> --
> Elliott Slaughter
>
> "Don't worry about what anybody else is going to do. The best way to
> predict the future is to invent it." - Alan Kay
>



-- 
Elliott Slaughter

"Don't worry about what anybody else is going to do. The best way to
predict the future is to invent it." - Alan Kay
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