Re: [petsc-users] Performance of the Telescope Multigrid Preconditioner

2016-10-07 Thread Dave May
On Friday, 7 October 2016, frank wrote: > Dear all, > > Thank you so much for the advice. > > All setup is done in the first solve. > > >> ** The time for 1st solve does not scale. >> In practice, I am solving a variable coefficient Poisson equation. I >> need to build the

Re: [petsc-users] Performance of the Telescope Multigrid Preconditioner

2016-10-07 Thread Barry Smith
> On Oct 7, 2016, at 4:49 PM, frank wrote: > > Dear all, > > Thank you so much for the advice. >> All setup is done in the first solve. >> >> ** The time for 1st solve does not scale. >> In practice, I am solving a variable coefficient Poisson equation. I >> need to

Re: [petsc-users] Performance of the Telescope Multigrid Preconditioner

2016-10-07 Thread Dave May
On 7 October 2016 at 02:05, Matthew Knepley wrote: > On Thu, Oct 6, 2016 at 7:33 PM, frank wrote: > >> Dear Dave, >> Follow your advice, I solve the identical equation twice and time two >> steps separately. The result is below: >> >> Test: 1024^3 grid

Re: [petsc-users] Performance of the Telescope Multigrid Preconditioner

2016-10-06 Thread Matthew Knepley
On Thu, Oct 6, 2016 at 7:33 PM, frank wrote: > Dear Dave, > Follow your advice, I solve the identical equation twice and time two > steps separately. The result is below: > > Test: 1024^3 grid points > Cores#reduction factorMG levels#time of 1st solve2nd time >

Re: [petsc-users] Performance of the Telescope Multigrid Preconditioner

2016-10-04 Thread Matthew Knepley
On Tue, Oct 4, 2016 at 3:26 PM, frank wrote: > > On 10/04/2016 01:20 PM, Matthew Knepley wrote: > > On Tue, Oct 4, 2016 at 3:09 PM, frank wrote: > >> Hi Dave, >> >> Thank you for the reply. >> What do you mean by the "nested calls to KSPSolve"? >> > >

Re: [petsc-users] Performance of the Telescope Multigrid Preconditioner

2016-10-04 Thread Matthew Knepley
On Tue, Oct 4, 2016 at 3:09 PM, frank wrote: > Hi Dave, > > Thank you for the reply. > What do you mean by the "nested calls to KSPSolve"? > KSPSolve is called again after redistributing the computation. > I tried to call KSPSolve twice, but the the second solve converged in

Re: [petsc-users] Performance of the Telescope Multigrid Preconditioner

2016-10-04 Thread frank
Hi Dave, Thank you for the reply. What do you mean by the "nested calls to KSPSolve"? I tried to call KSPSolve twice, but the the second solve converged in 0 iteration. KSPSolve seems to remember the solution. How can I force both solves start from the same initial guess? Thank you. Frank

Re: [petsc-users] Performance of the Telescope Multigrid Preconditioner

2016-10-04 Thread Dave May
On Tuesday, 4 October 2016, frank wrote: > Hi, > This question is follow-up of the thread "Question about memory usage in > Multigrid preconditioner". > I used to have the "Out of Memory(OOM)" problem when using the > CG+Telescope MG solver with 32768 cores. Adding the "-matrap

Re: [petsc-users] Performance of the Telescope Multigrid Preconditioner

2016-10-04 Thread Barry Smith
-ksp_view in both cases? > On Oct 4, 2016, at 1:13 PM, frank wrote: > > Hi, > > This question is follow-up of the thread "Question about memory usage in > Multigrid preconditioner". > I used to have the "Out of Memory(OOM)" problem when using the CG+Telescope > MG

Re: [petsc-users] Performance of the Telescope Multigrid Preconditioner

2016-10-04 Thread Matthew Knepley
On Tue, Oct 4, 2016 at 1:13 PM, frank wrote: > Hi, > This question is follow-up of the thread "Question about memory usage in > Multigrid preconditioner". > I used to have the "Out of Memory(OOM)" problem when using the > CG+Telescope MG solver with 32768 cores. Adding the