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seminars:seminar_03_25_14 [2014/03/26 13:02] (current)
kevincha created
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 +======Title: Improving DRAM Performance by Parallelizing Refreshes with Accesses======
 +==== Kevin Chang ====
 +== Tuesday, Mar. 25th, 4:00pm-5:00pm ==
 +== Hamerschlag Hall D-210 ==
 +===Abstract===
 +
 +Modern DRAM cells are periodically refreshed to prevent data loss due to     
 +
 +leakage. Commodity DRAM refreshes cells at the rank level. This degrades     
 +
 +performance significantly because it prevents an entire DRAM rank from serving
 +
 +memory requests while being refreshed. We propose two new complementary     
 +
 +techniques, DARP (Dynamic Access Refresh Parallelization) and SARP (Subarray 
 +
 +Access Refresh Parallelization), to mitigate the DRAM refresh penalty       
 +
 +by enhancing refresh-access parallelization at the bank and subarray levels, 
 +
 +respectively. DARP 1) issues per-bank refreshes to idle banks in an         
 +
 +out-of-order manner instead of issuing refreshes in a strict round-robin     
 +
 +order, 2) proactively schedules per-bank refreshes during intervals when a   
 +
 +batch of writes are draining to DRAM. SARP enables a bank to serve requests 
 +
 +from idle subarrays in parallel with other subarrays that are being refreshed.
 +
 +Extensive evaluations on a wide variety of workloads and systems show that our
 +
 +mechanisms improve system performance (and energy efficiency) compared to   
 +
 +state-of-the-art refresh policies.                                           
 +
 +
 +
 +===Bio===
 +
 +Kevin Chang is a third year PhD student in the Electrical and Computer       
 +
 +Engineering Department at Carnegie Mellon University, where he is advised by 
 +
 +Professor Onur Mutlu. His research focuses on improving performance and       
 +
 +energy-efficiency of memory sub-systems. He has also done work in the past on 
 +
 +high-performance on-chip interconnects. He received his B.S./M.S. in Electrical
 +
 +and Computer Engineering in 2011.