Hiding global synchronization latency in the preconditioned Conjugate Gradient algorithm.

Highlights: [•] The manuscript presents a highly scalable preconditioned Conjugate Gradient method. [•] It presents a pipelined preconditioned Conjugate Residual method. [•] It shows how global communication can be overlapped with local work. [•] It shows numerical stability of the methods. [•] It shows improved scalability and runtime compared to CG and CR. [ABSTRACT FROM AUTHOR]