{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T04:22:00Z","timestamp":1760242920294,"version":"build-2065373602"},"reference-count":10,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2016,10,25]],"date-time":"2016-10-25T00:00:00Z","timestamp":1477353600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"EU H2020 ICT-01-2014","award":["644042"],"award-info":[{"award-number":["644042"]}]},{"name":"General Secretariat for Research and Technology - ARISTEIA","award":["2427"],"award-info":[{"award-number":["2427"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Computation"],"abstract":"<jats:p>The motivation of this research was to evaluate the main memory performance of a hybrid super computer such as the Convey HC-x, and ascertain how the controller performs in several access scenarios, vis-\u00e0-vis hand-coded memory prefetches. Such memory patterns are very useful in stencil computations. The theoretical bandwidth of the memory of the Convey is compared with the results of our measurements. The accurate study of the memory subsystem is particularly useful for users when they are developing their application-specific personality. Experiments were performed to measure the bandwidth between the coprocessor and the memory subsystem. The experiments aimed mainly at measuring the reading access speed of the memory from Application Engines (FPGAs). Different ways of accessing data were used in order to find the most efficient way to access memory. This way was proposed for future work in the Convey HC-x. When performing a series of accesses to memory, non-uniform latencies occur. The Memory Controller of the Convey HC-x in the coprocessor attempts to cover this latency. We measure memory efficiency as a ratio of the number of memory accesses and the number of execution cycles. The result of this measurement converges to one in most cases. In addition, we performed experiments with hand-coded memory accesses. The analysis of the experimental results shows how the memory subsystem and Memory Controllers work. From this work we conclude that the memory controllers do an excellent job, largely because (transparently to the user) they seem to cache large amounts of data, and hence hand-coding is not needed in most situations.<\/jats:p>","DOI":"10.3390\/computation4040041","type":"journal-article","created":{"date-parts":[[2016,10,25]],"date-time":"2016-10-25T10:28:49Z","timestamp":1477391329000},"page":"41","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Evaluation of External Memory Access Performance on a High-End FPGA Hybrid Computer"],"prefix":"10.3390","volume":"4","author":[{"given":"Konstantinos","family":"Kalaitzis","sequence":"first","affiliation":[{"name":"School of Electrical and Computer Engineering, Technical University of Crete, Chania 731 00, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Evripidis","family":"Sotiriadis","sequence":"additional","affiliation":[{"name":"School of Electrical and Computer Engineering, Technical University of Crete, Chania 731 00, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ioannis","family":"Papaefstathiou","sequence":"additional","affiliation":[{"name":"School of Electrical and Computer Engineering, Technical University of Crete, Chania 731 00, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Apostolos","family":"Dollas","sequence":"additional","affiliation":[{"name":"School of Electrical and Computer Engineering, Technical University of Crete, Chania 731 00, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2016,10,25]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"80","DOI":"10.1109\/MCSE.2010.135","article-title":"High-performance heterogeneous computing with the Convey HC-1","volume":"12","author":"Bakos","year":"2010","journal-title":"Comput. Sci. Eng."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Jones, D.H., Powell, A., Bouganis, C.-S., and Cheung, P.Y.K. (September, January 31). GPU versus FPGA for high productivity computing. Proceedings of the 2010 International Conference on Field Programmable Logic and Applications (FPL), Milano, Italy.","DOI":"10.1109\/FPL.2010.32"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Betkaoui, B., Thomas, D.B., and Luk, W. (2010, January 8\u201310). Comparing performance and energy efficiency of FPGAs and GPUs for high productivity computing. Proceedings of the 2010 International Conference on Field-Programmable Technology (FPT), Beijing, China.","DOI":"10.1109\/FPT.2010.5681761"},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Nagar, K.K., and Bakos, J.D. (2011, January 1\u20133). A sparse matrix personality for the convey HC-1. Proceedings of the 2011 IEEE 19th Annual International Symposium on Field-Programmable Custom Computing Machines (FCCM), Salt Lake City, UT, USA.","DOI":"10.1109\/FCCM.2011.60"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Weisz, G., Melber, J., Wang, Y., Fleming, K., Nurvitadhi, E., and Hoe, J.C. (2016, January 21\u201323). A Study of Pointer-Chasing Performance on Shared-Memory Processor-FPGA Systems. Proceedings of the 2016 ACM\/SIGDA International Symposium on Field-Programmable Gate Arrays, Monterey, CA, USA.","DOI":"10.1145\/2847263.2847269"},{"key":"ref_6","unstructured":"Maas, M., Love, E., Stefanov, E., Tiwari, M., Shi, E., Asanovi, K., Kubiatowicz, J., and Song, D. (2013, January 7). A high-performance oblivious RAM controller on the convey HC-2ex heterogeneous computing platform. Proceedings of the Workshop on the Intersections of Computer Architecture and Reconfigurable Logic (CARL), Davis, CA, USA."},{"key":"ref_7","unstructured":"Jin, Z. (2014). Memory Interface Synthesis for FPGA-Based Computing. [Ph.D. Thesis, University of South Carolina]."},{"key":"ref_8","unstructured":"Convey (2012). Convey Personality Development Kit Reference Manual, Convey Computer. Version 5.2."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"133","DOI":"10.1093\/nar\/9.1.133","article-title":"Optimal computer folding of large RNA sequences using thermodynamics and auxiliary information","volume":"9","author":"Zuker","year":"1981","journal-title":"Nucleic Acids Res."},{"key":"ref_10","unstructured":"Markham, N.R., and Michael, Z. (2008). Bioinformatics, Humana Press."}],"container-title":["Computation"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-3197\/4\/4\/41\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T19:33:51Z","timestamp":1760211231000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-3197\/4\/4\/41"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2016,10,25]]},"references-count":10,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2016,12]]}},"alternative-id":["computation4040041"],"URL":"https:\/\/doi.org\/10.3390\/computation4040041","relation":{},"ISSN":["2079-3197"],"issn-type":[{"type":"electronic","value":"2079-3197"}],"subject":[],"published":{"date-parts":[[2016,10,25]]}}}