> Maximum memory PetscMalloc()ed 29246912 maximum size of entire process 0
The choice of wording here is a bit misleading. PETSc is using getrusage(ru_maxrss) - which is resident set size. [so top should show similar numbers got RSS] This might include both code segment and data segments - and the code segment part could be a few MB - perhaps up to 10 MB] 0: [0] 10 15321472 MatSeqAIJSetPreallocation_SeqAIJ() This indicates that the matrix is taking approximately 15MB. And there are other datastructures that are taking about another couple of MB space. Depending upon how the malloc()/free() is implemented in the OS - some of the freed memory might not immediately reflect on th RSS count. Hope this helps.. Satish On Wed, 28 Feb 2007, Shi Jin wrote: > Hi, > I am curious how much extra memory PETSc allocates in > the background. Since my estimate of memory usage of > the code is much smaller than what I see when it runs. > So I did this simple test: > First I used PETSc to dump a matrix in binary format > into a file. The file has a size of 13MB. I assume > this should be the same size that is used to store the > matrix in memory. Then I wrote a simple code that does > nothing but to load this matrix from the file by > MatLoad(). However, I found that the code consumes > 29MB of memory (VIRT=29M from top) using single > process. > This is confirmed by the -malloc_log option where it > says > Maximum memory PetscMalloc()ed 29246912 maximum size > of entire process 0 > I've attached the output of the code with detailed > malloc information. > Could you please explain to me about the difference > of over two time? > I don't want to criticize anything but need an clear > idea of how much memory is needed so that I know > whether there is a chance for me to reduce the memory > usage of my production code. > Thank you very much. > > Shi > > > > ____________________________________________________________________________________ > Need a quick answer? Get one in minutes from people who know. > Ask your question on www.Answers.yahoo.com
