Memory Team has Two Papers Accepted at DATE 2015

The notifications from the DATE conference are in and the Memory Team scores 2 out of 2, just like in 2014. The first paper entitled “A Generic, Scalable and Globally Arbitrated Memory Tree for Shared DRAM Access in Real-Time Systems” was first-authored by Manil and is a collaboration with Jamie Garside and Neil Audsley from University of York. The paper proposes a memory interconnect for shared memory architectures in many-core systems. A main architectural feature is that the interconnect is heavily pipelined enabling it to be synthesized at high frequencies even with a large number of clients. Another highlight is that it has global arbitration that can be programmed to behave like several different arbitration mechanisms, such as TDM, CCSP and FBSP.

The second paper “Retention Time Measurements and Modelling of Bit Error Rates of WIDE I/O DRAM in MPSoCs”was first-authored by our colleagues at Kaiserslautern University of Technology in collaboration with Sven Goossens from our Memory Team. This paper looks into the thermal behavior of 3D-stacked WIDE I/O DRAM and compares its impact on retention time and bit error rates to conventional 2D DRAM chips.

Visiting Researcher at Airbus Group Innovations

Today, I start a two month stay as Visiting Researcher at Airbus Group Innovations in Ottobrunn, Germany. I will be working together with Jan Nowotsch on topics related to performance analysis of memory accesses in COTS multi-core platforms. During my stay, I look forward to meeting new people learning more about real-time systems in the avionics domain.

DRAMPower v4.0 Released!

A new version of the DRAMPower tool has been released. The two main features of version 4 are:

  1. DRAMPower can now be compiled as a library. This enables a user to access the tool through an API and log commands and their corresponding time stamps, removing the need to store large command traces on disk. The key benefit of this feature is that users can easily integrate DRAMPower into their own memory controller simulators and obtain power and energy consumption estimates. In fact, this version of DRAMPower is already integrated into the memory controller of the gem5 simulator system and is provided with the latest release.
  2. Improved robustness. The latest build is checked out every night on a test server, compiled, and tested to verify that the output matches an expected reference for a battery of tests. The code is also compiled with a large number of warning flags enabled and treats all warnings as errors. This feature makes it easier for the community to reliably contribute to the tool, which is now possible through github.

Check it out the new version of DRAMPower here.

First PhD Student Graduates From the Memory Team

Today, Karthik Chandrasekar was promoted to doctor as he confidently defended his PhD thesis “High-Level Power Estimation and Optimization of DRAMs”. The thesis proposes a high-level power estimation tool called DRAMPowerthat estimates the power and energy consumption of different generations of DRAMs based on a memory command trace and current values from the memory datasheet. Since current numbers in datasheets are often pessimistic for a majority of the manufactured memory devices, a methodology is also proposed to characterize DRAM modules post-manufacturing to achieve more accurate power and performance estimates for the characterized devices. Lastly, the thesis discusses power optimization in the context of real-time memory controllers and proposes two power-down strategies to reduce the power consumption of memories in real-time systems without sacrificing worst-case performance.

The defense went very well and the committee was particularly pleased with how the DRAMPower tool was verified using measurements on real hardware and how it has attracted interest from industry. Karthik is the first PhD student to graduate from the Memory Team and the rest of the team wishes him all the best for his future career at Nvidia.