# KSPPIPECG#

Pipelined conjugate gradient method. Pipelined Krylov Methods

## Notes#

This method has only a single non-blocking reduction per iteration, compared to 2 blocking for standard CG. The non-blocking reduction is overlapped by the matrix-vector product and preconditioner application.

See also KSPPIPECR, where the reduction is only overlapped with the matrix-vector product and KSPGROPPCG

MPI configuration may be necessary for reductions to make asynchronous progress, which is important for performance of pipelined methods. See What steps are necessary to make the pipelined solvers execute efficiently?

## Contributed by#

Pieter Ghysels, Universiteit Antwerpen, Intel Exascience lab Flanders

## Reference#

P. Ghysels and W. Vanroose, “Hiding global synchronization latency in the preconditioned Conjugate Gradient algorithm”, Submitted to Parallel Computing, 2012.

KSP: Linear System Solvers, What steps are necessary to make the pipelined solvers execute efficiently?, Pipelined Krylov Methods, KSPCreate(), KSPSetType(), KSPPIPECG2, KSPPIPECR, KSPGROPPCG, KSPPGMRES, KSPCG, KSPCGUseSingleReduction()