You need to provide more information. What is the output of -ksp_view? and -log_view? for both cases
> On Jun 12, 2017, at 7:11 PM, Ji Zhang <[email protected]> wrote: > > Dear all, > > I'm a PETSc user. I'm using GMRES method to solve some linear equations. I'm > using boundary element method, so the matrix type is dense (or mpidense). I'm > using MPICH2, I found that the convergence is fast if I only use one computer > node; and much more slower if I use two or more nodes. I'm interested in why > this happen, and how can I improve the convergence performance when I use > multi-nodes. > > Thanks a lot. > > 此致 > 敬礼 > 张骥（博士研究生） > 北京计算科学研究中心 > 北京市海淀区西北旺东路10号院东区9号楼 （100193） > > Best, > Regards, > Zhang Ji, PhD student > Beijing Computational Science Research Center > Zhongguancun Software Park II, No. 10 Dongbeiwang West Road, Haidian > District, Beijing 100193, China
