Affiliations: Computer and Systems Research Laboratory, University
of Illinois at Urbana-Champaign, 1308 West Main Street, Urbana, IL 61801, USA.
E-mail: {dsn,cdp}@csrd.uiuc.edu | Department of Computer Engineering and Informatics,
University of Patras, GR26500, Patras, Greece. E-mail:
tsp@hpclab.ceid.upatras.gr | Department of Computer Architecture, Technical
University of Catalonia, c/Jordi Girona 1-3, 08034, Barcelona, Spain. E-mail:
{jesus,eduard}@ac.upc.es
Note: [] Corresponding author
Abstract: This paper makes two important contributions. First, the paper
investigates the performance implications of data placement in OpenMP programs
running on modern NUMA multiprocessors. Data locality and minimization of the
rate of remote memory accesses are critical for sustaining high performance on
these systems. We show that due to the low remote-to-local memory access
latency ratio of contemporary NUMA architectures, reasonably balanced page
placement schemes, such as round-robin or random distribution, incur modest
performance losses. Second, the paper presents a transparent, user-level page
migration engine with an ability to gain back any performance loss that stems
from suboptimal placement of pages in iterative OpenMP programs. The main body
of the paper describes how our OpenMP runtime environment uses page migration
for implementing implicit data distribution and redistribution schemes without
programmer intervention. Our experimental results verify the effectiveness of
the proposed framework and provide a proof of concept that it is not necessary
to introduce data distribution directives in OpenMP and warrant the simplicity
or the portability of the programming model.
