- firedrake - imperial.ac.uk

Next group meeting
by Lawrence Mitchell 25 Jul '14

25 Jul '14

Dear all, due to restricted numbers this week, there will be no meeting on Friday. Next week, we will convene on Tuesday 29th to maximise the number of people here. I suggest at 3pm. We're currently in a state of flux and it's unclear whether WPL will be available next week, so I will update with venue as and when. Cheers, Lawrence

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A note about Python objects
by Martin Sandve Alnæs 23 Jul '14

23 Jul '14

In UFL code contributed from the Firedrake team, there are some comments I'd like to address: The __eq__ operator of any Python object is used to compare for equality in set and dict if __hash__ compares equal. The __lt__ operator is used to define sorting, e.g. sorted(myobjects) will use this operator. Together these operators allow e.g. sorted(set(myobjects)) to get a sorted unique list. It's not necessarily important for the sorting to have any meaning, however it is important that it is deterministic between runs and platforms. Raising custom exceptions (including calling error()) in a Python special function is always a bug. The correct behaviour is to "return NotImplemented", which allows Python to follow its regular protocols. E.g. when writing A < B, if A.__lt__(B) returns NotImplemented, Python will try B.__lt__(A). If any of this was news and you're writing significant Python code, I recommend reading more here: https://docs.python.org/2/reference/datamodel.html Martin

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Re: [firedrake] PDESoft 2014 slides
by David Ham 13 Jul '14

13 Jul '14

On Saturday, July 12, 2014, Rathgeber, Florian <f.rathgeber10(a)imperial.ac.uk> wrote: > On 12/07/14 08:06, David Ham wrote: > > > > Those look like interesting results. > > > > Do we have any idea why we are slow on CUDA on the RHS? > > The reason is that afaict the kernel uses too many resources: 57 > registers and 28.047K of shared memory. We therefore get a theoretical > occupancy of 6.25% i.e. only 1/16 SMX units on the 680 can be used. That > is up to 64 DP FMAs at half the clock speed of a Xeon core... > > oK. that's a good analysis, make sure you give yourself time to give it. It'll make the audience realise you really know what you are doing. > > Do we have any indication of actual speed compared with peak flops or > > bandwidth? > > I haven't been able to figure out how to drive the Nvidia profiler to > record the required metrics, but we should be able to get those somehow. > > Florian > > > Regards, > > > > David > > > > > > > > On Friday, July 11, 2014, Rathgeber, Florian > > <f.rathgeber10(a)imperial.ac.uk <javascript:;> <mailto: > f.rathgeber10(a)imperial.ac.uk <javascript:;>>> wrote: > > > > I have now added performance results for advection assembly (matrix + > > RHS). We can still claim (performance) portability to some degree > across > > sequential, OpenMP and CUDA. > > > > On 10/07/14 11:23, David Ham wrote: > > > I'm concerned that there are no performance results at all. Do we > not > > > even have CPU results? > > > > > > On Wednesday, July 9, 2014, Rathgeber, Florian > > > <f.rathgeber10(a)imperial.ac.uk <javascript:;> <javascript:;> > > <mailto:f.rathgeber10@imperial.ac.uk <javascript:;> > <javascript:;>>> wrote: > > > > > > Draft slides for my 15min PDESoft talk on PyOP2 next week are > at > > > http://kynan.github.io/pdesoft2014 > > > > > > Any comments and suggestions much appreciated. > > > > > > Florian > > -- Dr David Ham Departments of Mathematics and Computing Imperial College London http://www.imperial.ac.uk/people/david.ham

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Re: [firedrake] PDESoft 2014 slides
by David Ham 12 Jul '14

12 Jul '14

Those look like interesting results. Do we have any idea why we are slow on CUDA on the RHS? Do we have any indication of actual speed compared with peak flops or bandwidth? Regards, David On Friday, July 11, 2014, Rathgeber, Florian <f.rathgeber10(a)imperial.ac.uk> wrote: > I have now added performance results for advection assembly (matrix + > RHS). We can still claim (performance) portability to some degree across > sequential, OpenMP and CUDA. > > On 10/07/14 11:23, David Ham wrote: > > I'm concerned that there are no performance results at all. Do we not > > even have CPU results? > > > > On Wednesday, July 9, 2014, Rathgeber, Florian > > <f.rathgeber10(a)imperial.ac.uk <javascript:;> <mailto: > f.rathgeber10(a)imperial.ac.uk <javascript:;>>> wrote: > > > > Draft slides for my 15min PDESoft talk on PyOP2 next week are at > > http://kynan.github.io/pdesoft2014 > > > > Any comments and suggestions much appreciated. > > > > Florian > > -- Dr David Ham Departments of Mathematics and Computing Imperial College London http://www.imperial.ac.uk/people/david.ham

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Re: [firedrake] PDESoft 2014 slides
by David Ham 11 Jul '14

11 Jul '14

I'm concerned that there are no performance results at all. Do we not even have CPU results? On Wednesday, July 9, 2014, Rathgeber, Florian <f.rathgeber10(a)imperial.ac.uk> wrote: > Draft slides for my 15min PDESoft talk on PyOP2 next week are at > http://kynan.github.io/pdesoft2014 > > Any comments and suggestions much appreciated. > > Florian > > -- Dr David Ham Departments of Mathematics and Computing Imperial College London http://www.imperial.ac.uk/people/david.ham

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PDESoft 2014 slides
by Florian Rathgeber 09 Jul '14

09 Jul '14

Draft slides for my 15min PDESoft talk on PyOP2 next week are at http://kynan.github.io/pdesoft2014 Any comments and suggestions much appreciated. Florian

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solver options
by Colin Cotter 05 Jul '14

05 Jul '14

Hi all, We have been trying to use the shiny new option to specify a different matrix for the solver, but within LinearVariationalSolver. With this usage, it fails for us, probably because we are mispecifying the options. The following code tries to solve it first using the solve() command, then with LinearVariationalSolver. https://gist.github.com/colinjcotter/fd72f3a838ce46d0fe7d Please can you tell us what we are doing wrong? cheers --cjc

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Video of flow past a square
by Jacobs, Christian T 04 Jul '14

04 Jul '14

Adding to the collection of pretty Firedrake-related videos, here's a video of flow past a square: https://www.youtube.com/watch?v=JIBKMF6rK8s&feature=youtu.be Cheers, Christian

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Re: [firedrake] compile problem
by Andrew McRae 04 Jul '14

04 Jul '14

On second thoughts, I think you're just missing a comma in front of the t=t? On 3 July 2014 18:57, Shipton, Jemma <j.shipton(a)imperial.ac.uk> wrote: > Hi All, > > Sorry to post a question in the chat and then disappear - I'd lost track > of time and needed to dash home. Anyway, I've copied and pasted my > question... > > 18:26 < jemma> I have pulled some code Colin added this morning > 18:27 < jemma> and it doesn't work - although Colin was quite happily > running > it before he went to watch tennis > 18:27 < jemma> can anyone see why there'd be a problem with this: > 18:27 < jemma> u = project(Expression(("1.0 + > > sin(pi*(x[0]-t))*sin(pi*x[1])*cos(pi*t/T0)","cos(pi*(x[0]-t))*cos(pi*x[1])*cos(pi*t/T0)")t=t,T0=T0),V1) > 18:28 < jemma> where V1 comes from: > 18:28 < jemma> V1_v = OuterProductElement(IUh1, IUv0) > 18:28 < jemma> V1_h = OuterProductElement(IUh0, IUv1) > 18:28 < jemma> V1_elt = HDiv(V1_v) + HDiv(V1_h) > 18:28 < jemma> V1 = FunctionSpace(mesh,V1_elt) > 18:28 < jemma> t and T0 are defined > 18:29 < jemma> maybe I'm missing a ufl/pyop2/something update - I haven't > updated in a while... > > When I run the code won't even compile: > > pyop2.exceptions.CompilationError: Unable to compile code > > I've attached the log and err files. The problem seems to be the variables > t and T0 in the expression - although they are defined in previous lines: > > t = 0.0 > T0 = 1.0 > > The script I'm trying to run is at: > https://bitbucket.org/colinjcotter/vertical-tests/src/c1a2a565912564897fdbe… > > Thanks! > > Jemma >

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A fun video to end the day
by Andrew McRae 03 Jul '14

03 Jul '14

DG advection + extruded circle mesh + coordinate-field editing = https://dl.dropboxusercontent.com/u/62309663/tyre.mp4

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