[parsec-users] fluidanimate questions
cbienia at CS.Princeton.EDU
Sun Aug 24 13:34:11 EDT 2008
Let me get in touch with the developers of fluidanimate. They probably know
best what's going on here.
From: parsec-users-bounces at lists.cs.princeton.edu
[mailto:parsec-users-bounces at lists.cs.princeton.edu] On Behalf Of Milo
Sent: Saturday, August 23, 2008 9:16 PM
To: parsec-users at lists.cs.princeton.edu
Subject: Re: [parsec-users] fluidanimate questions
An update on the fuildanimate bug.
I was doing some testing with the "fix" I mentioned earlier today, and
the benchmark now crashes.
It seems the benchmark has a hard-coded assumption that each "cell" of
the volume can have at most 16 particles in it. If a cell has more
than that, the array accesses go beyond the size of the fixed-sized
array, eventually causing a segmentation fault.
It looks like fixing this would require changes to the data structures
On Aug 23, 2008, at 8:43 PM, Milo Martin wrote:
> I've rediscovered the same bug in fluidanimate that Mark Hampton
> asked about earlier.
> The cells2 array really isn't being changed after initialization,
> so the exact same computations runs each timestep.
> It seems that all that is needed to fix the benchmark would be two
> calls to std::swap() at the end of each iteration. Once to swap the
> cells2 and cells pointers and once to swap the cnumPars and
> cnumPars2 pointers.
> This bug is present in the original serial version, so it wasn't
> introduced during parallelization.
> Is there any way to verify this problem and find out if this is
> indeed the right fix?
> - Milo Martin
> Milo M. K. Martin (milom at cis.upenn.edu)
> Assistant Professor
> Computer and Information Sciences Department
> University of Pennsylvania
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