Dear all,? Are you seeing the memory used by those vectors being a significant part of the overall memory usage of the program??
To this question, I think yes.? Is it also normal, number of vectors is dependent upon how many levels used ? ? I experienced this. When I increase levels in PCMG, number of vectors used (created and destroyed) increases.? Thanks,? Abdul . >________________________________ > From: Jed Brown <jedbrown at mcs.anl.gov> >To: Abdul Hanan Sheikh <hanangul12 at yahoo.co.uk>; PETSc users list ><petsc-users at mcs.anl.gov> >Sent: Thursday, 24 May 2012, 22:06 >Subject: Re: [petsc-users] Multigrid Vcycle. > > >On Thu, May 24, 2012 at 2:29 PM, Abdul Hanan Sheikh <hanangul12 at >yahoo.co.uk> wrote: > >Thanks for early response Jed!, >> >>I fixed outer Krylov as PREONLY so it does not use any vectors (I guess).? >>Standard Vcycle includes 1 pre and 1 post smoothing. >> >>KSP-Richardson + PC-Jacobi are ingredients for pre-smoothing and? post >>smoothing.? >>To my understanding, 2 Vectors are used by KSP Richardson + 1 Vector is used >>by PC-Jacobi? >>at pre and post smoothing. This makes 6 vectors at each level and for 5 >>levels, they should be 30! >> > > >DMSetUp_DA_nD creates and destroys two vectors as part of its set up process. >There is also a scaling vector associated with restriction (so that >restriction and prolongation can use the same matrix, which they usually do), >including a momentary work vector used to compute the scaling. So many of >those vectors are not alive at once. > > >Are you seeing the memory used by those vectors being a significant part of >the overall memory usage of the program? > > >Barry,? >? > >> >>Do I think right ? >> >>Further hint to make PCMG more memory-efficient is appreciated. >>with warm regard, Abdul >> >> >> >> >> >>>________________________________ >>> From: Jed Brown <jedbrown at mcs.anl.gov> >>>To: Abdul Hanan Sheikh <hanangul12 at yahoo.co.uk>; PETSc users list >>><petsc-users at mcs.anl.gov> >>>Sent: Thursday, 24 May 2012, 21:22 >>>Subject: Re: [petsc-users] Multigrid Vcycle. >>> >>> >>> >>>On Thu, May 24, 2012 at 2:14 PM, Abdul Hanan Sheikh <hanangul12 at >>>yahoo.co.uk> wrote: >>> >>>Dear all, >>>> >>>>I am quit beginner in PETSc. >>>> >>>>I wrote a code for multigrid Vcycle (as preconditioer) by following the >>>>instructions on manual page. >>>> >>>>I want to see how much memory a Vcycle allocates by default in terms of >>>>number of matrices and vectors. >>>> >>>>I made a try to see by comparing with jacobi preconditioner, which surely >>>>allocates 1 vector ONLY. >>>> >>>>It turns out that a VCycle for FIVE (5) levels including coarsest level >>>>allocates memory for 53 vectors and >>>> >>>>subsequently it destroys too. >>> >>> >>>Some of those vectors are very small due to being on the coarse level. There >>>are also the vectors used by the outer Krylov method. >>>? >>> >>>> >>>>Is it normal ?? >>>> >>>> >>>> >>>> >>>> >>>>Thanks in advance, >>>> >>>>Abdul >>>> >>> >>> >>> > > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120525/99026ad2/attachment.html>
