Speaker
Dr
Chulwoo Jung
(Brookhaven National Laboratory)
Description
The increasing unbalance between computing capabilities of individual
nodes and internode communication makes it highly desirable for any
Lattice QCD algorithm to minimize the amount of off-node communication.
One of the relatively new methods for this is the 'split-grid' or
'split-domain', where data is rearranged within the running of a single binary,
so that the routines which requires significant off-node communications such
as Dirac operators are run on multiple smaller partitions in parallel
with a better surface to volume ratio,
while other routines are run in one large partition.
While it is relatively straightforward to utilize split-grid for
inverters, the typical
Lanczos algorithm which has one starting vector does not render itself
naturally to split-grid approach. Here we report on our investigation of Block
Lanczos algorithm which allows multiple starting vectors to be concurrently.
It is shown that for a moderate number of starting vectors, Block
Lanczos algorithm has been implemented in Grid Data parallel C++ mathematical object library, and shown to achieve convergence comparable to normal Lanczos algorithm on
DWF/Mobius ensemble with physical quark masses.
Primary authors
Dr
Chulwoo Jung
(Brookhaven National Laboratory)
Dr
Yong-Chull Jang
(Brookhaven National Laboratory)