I'm Lokesh Siddhu

Thermal Aware Runtime Management of 3D Architecture:

Introduction:

Traditional memory design is unable to serve modern data needs-
With the growing video and audio content/data, the amount of memory (RAM) required is increasing. Also, many application access large amounts of data in a short span of time. To address these issues, memory (RAM) designers have kept on increasing the density and frequency of memory devices. However, device scaling has reached saturation, and it's becoming difficult to manufacture small sized memory cells reliably. We need newer memory technologies to address these challenges.

3D Integration: An opportunity-
Traditional memories arrays have rectangular (row-column) layout, and memory cells are present at the intersection of row and column. One of the proposed ideas (to overcome the challenges) is to stack (and interconnect) multiple memory arrays in a 3D structure. Stacking will help store large amounts of data in a small area and also, a large number of interconnects will allow fast data access (in a short time).

Thermal Challenges in 3D Integration-
3D memories offer other advantages (as well) like lower interconnect power (because of shorter wiring) and ability to stack memories designed on different technologies (heterogeneous technology integration). However, the power per unit area increases (due to stacking) and heat dissipation becomes difficult due to which 3D devices can get (quickly) overheated.

Is heating a problem?
Electronic components work reliably only in a particular (operating) temperature range. If overheated, the device cannot be accessed (stalled), and they are allowed to cool down (cooling time). Desktops and servers are usually kept in air-conditioned rooms (incurring considerable cooling costs) so that operating temperature ranges are not exceeded frequently. Further, we regularly see on mobile devices (like laptop, mobiles) that users are unable to use the device if it's too hot (temperature might still be in the operating range).

Goal of our research-
For a system with 3D memory, run applications without violating the thermal limit while maximizing the performance of the system.

Alleviating Thermal Challenges by Data Mapping-
Heat dissipation is a significant challenge in 3D technologies. Heat sinks provide an efficient cooling solution and can cool down the top layers of the memory. However, the bottom layers have limited heat dissipation paths. We can map frequently accessed data on the top layers so that the memory doesn't get heated (often) and hence, reduce the stalls.

Abstract: Research in 3D integration has attracted researchers from industries as well as academics due to its benefits over 2D architecture such as better performance, lower power consumption, small form factor and support for heterogeneous technology integration. Furthermore, various 3D memories architectures have been proposed by industries/academia to cater to the high bandwidth requirement at low power. However, due to its higher power density and reduced heat dissipation properties, heat dissipation is one of the major challenges in the promising 3D integration technology. In this research, we aim to design thermal aware data/task mapping policies for 3D architectures.

Publication: Siddhu, Lokesh, and Preeti Ranjan Panda. "Thermal aware runtime management of 3D memory architecture." CSI transactions on ICT 5.2 (2017): 129-134.