On Monday February 21 2011 12:31:18 Garth N. Wells wrote: > On 21/02/11 18:00, Johan Hake wrote: > > On Monday February 21 2011 08:18:18 Garth N. Wells wrote: > >> On 17/02/11 21:28, Johan Hake wrote: > >>> Hello! > >>> > >>> I have a not so large 3D mesh of some 50K vertices, generated from some > >>> geometry (not UnitCube). > >>> > >>> When I set > >>> > >>> parameters.num_threads = 2 > >>> > >>> and try to assemble I just get: > >>> Coloring mesh. > >>> > >>> and then it seems it wont find a solution... I had to break it because > >>> it nearly hang the computer for some 5 min. > >>> > >>> Have anyone experience the same? Is there any way to controll the > >>> coloring? > >> > >> It's had minimal testing, so issues can be expected. Can you post your > >> solver? 50k vertices is not very big, so I would expect it to be pretty > >> fast. > > > > Yes I would expect that too. I have used the coloring on other meshes > > with success. > > > > The mesh can be downloaded from here: > > <http://folk.uio.no/hake/trouble.xml.gz> > > > > To reproduce the trouble just run: > > from dolfin import * > > mesh = Mesh('trouble.xml.gz') > > V = FunctionSpace(mesh, "CG", 1) > > assemble(Function(V)*dx) > > parameters.num_threads = 2 > > assemble(Function(V)*dx) > > > > The mesh has two distinct domains, but that shouldnto be causing the > > trouble, as other I have successfully colored other such meshes. I guess > > it can be the particular mesh that causes coloring to stall. It is > > generated using tetgen. > > I don't think that I've tested multi-threaded assembly for functionals. > > When we get around to implementing it, assembling functionals shouldn't > require colouring. It should just involve OpenMP parallelising the > assembly loop, and then each thread adds its contribution to the result > once it's processed its bunch of cells (while avoiding a race condition).
I just used a Functional so I could stick with a shorter example ;) The above code works fine with another mesh. Changing the form to a linear or bilinear form triggers the same coloring (right?), which stalls on this particular mesh. Johan > Garth > > > At the end of the day I have to wait untill we support subdomains in the > > OpenMPAssembler as I am heavily using these... > > > > Johan > > > >> Garth > >> > >>> Johan > >>> > >>> _______________________________________________ > >>> Mailing list: https://launchpad.net/~dolfin > >>> Post to : [email protected] > >>> Unsubscribe : https://launchpad.net/~dolfin > >>> More help : https://help.launchpad.net/ListHelp > >> > >> _______________________________________________ > >> Mailing list: https://launchpad.net/~dolfin > >> Post to : [email protected] > >> Unsubscribe : https://launchpad.net/~dolfin > >> More help : https://help.launchpad.net/ListHelp > > _______________________________________________ > Mailing list: https://launchpad.net/~dolfin > Post to : [email protected] > Unsubscribe : https://launchpad.net/~dolfin > More help : https://help.launchpad.net/ListHelp _______________________________________________ Mailing list: https://launchpad.net/~dolfin Post to : [email protected] Unsubscribe : https://launchpad.net/~dolfin More help : https://help.launchpad.net/ListHelp
