-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 27/04/15 16:06, Lawrence Mitchell wrote: > Dear all, > > we recently noticed a slowdown when using GAMG that I'm trying to > track down in a little more detail. I'm solving an Hdiv-L2 > "helmholtz" pressure correction using a schur complement. I > precondition the schur complement with 'selfp', which morally looks > like a normal Helmholtz operator (except in the DG space). The domain > is very anisotropic (a thin atmospheric shell), so getting round to > trying Toby's column-based coarsening plugin is on the horizon but I > haven't done it yet. > > I don't have a good feel for exactly when things go worse, but here > are two data points: > > A recentish master (e4b003c), and master from 26th Feb (30ab49e4). I > notice in the former that MatPtAP takes significantly longer (full > logs below), different coarsening maybe? As a point of comparison, > the PCSetup for Hypre takes ballpark half a second on the same operator. > > I test with KSP ex6 (with a constant RHS): > > Any ideas?
I should have mentioned, a MatLoadable matrix is available at: http://www.doc.ic.ac.uk/~lmitche1/ Lawrence -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJVPlHkAAoJECOc1kQ8PEYvDAoH/0bN3QpIyel3SekcMa/M63EN 5k37bPfkFWj+B49bUEwvB1f3+GhakFLYQieVnsLWHoLsGjDIZo7AgmrUIJZkR0gx HoKcyh3NnSkw4nzsi91FQC3zqhBVJ1Vcyugmlp+xtT86CKRb69w+vHlzS7/onabv j+4cXw2ZXGUKB3xrG4ka2QKP4wudfIk2ZmrN++2G//tzhPjM00Wwn9fNb5b8LFtW dzj8u06dt9HjSzxem0sUYLCrWNSUGM1FNGEr8uuNlttE8qf4lCAlWLupx8ywfcnH g0twzTnvgQTqfLfvQFnQVL30F5i0D1BlTscTn6jlenOGx4pwe7Hjuqym+dIK4tE= =41dp -----END PGP SIGNATURE-----
