arXiv subjects

Jikun Wang

Publications and source records attributed to Jikun Wang.

3 recordsLinked to original sources

arXiv2026

PuDGhost: Experimental Analysis of Computation Result Corruption in Processing-using-DRAM Operations on Real DRAM Chips and Implications for Future Systems

Processing-using-DRAM (PuD) is a promising computation paradigm that alleviates frequent data movement between main memory and processing units by using each DRAM column as a computation engine via simultaneous multiple-row activation (SiMRA). Unfortunately, DRAM density scaling may hinder PuD's benefits: denser cell arrays bring rows and columns closer, making regular DRAM operations susceptible to noise and interference from neighboring cells. Yet no prior work investigates whether interference from rows or columns not intended to participate in computation can compromise PuD robustness. In this work, we reveal PuDGhost, an interference phenomenon where a PuD operation in a given column produces erroneous results due to interference from 1) data in non-activated DRAM rows and 2) data in other columns that compute concurrently under the same SiMRA operation. PuDGhost violates the ideal picture that each column's computation depends solely on its own operand data, threatening future PuD systems. We present the first extensive characterization of PuDGhost using 96 real DDR4 DRAM chips from 12 modules, quantifying these two interference sources under various conditions. Among our 15 new empirical observations, we highlight two major results: 1) data in adjacent non-activated rows affects SiMRA outputs by up to 10% for random inputs, and 2) data in concurrently computing columns affects SiMRA outputs by up to 48% for random inputs. Guided by these findings, we propose countermeasures across multiple layers of the PuD computing stack. Specifically, we evaluate on real DDR4 DRAM chips: 1) robust column screening that reduces the risk of using unreliable columns in the presence of PuDGhost, and 2) a compute row layout that mitigates PuDGhost via dedicated rows between compute rows. Our solutions greatly improve PuD computation accuracy and provide a foundation for robust future PuD systems.

cs.AR↗

arXiv2026

ScaleDisturb: Exploiting Temporal Asymmetry to Amplify Read Disturbance in Modern DRAM Chips

DRAM suffers from read disturbance phenomena (e.g., RowHammer and RowPress), where repeatedly accessing or continuously keeping open a DRAM row (aggressor row) induces bitflips in other physically nearby unaccessed rows (victim rows). The disturbance mechanism is practically exploitable from the software stack and worsens across generations with continued density scaling. DRAM read disturbance is highly sensitive to memory access patterns, yet prior work explores read disturbance under only a limited set of access patterns. We present ScaleDisturb, a new DRAM access pattern that can amplify DRAM read disturbance by asymmetrically extending the open time of two aggressor rows. Our rigorous experimental characterization of 196 DDR4 and 3 HBM2 DRAM chips shows that ScaleDisturb (1) leads to bitflips at significantly fewer row activations, compared to state-of-the-art memory access patterns, (2) makes read disturbance attacks easier across all tested DRAM chips, (3) increases DRAM vulnerability to read disturbance as DRAM manufacturing technology scales down to smaller node sizes. We showcase a proof-of-concept attack on a real system where a user-level program leveraging ScaleDisturb induces more bitflips than state-of-the-art RowHammer and RowPress memory access patterns. We describe and evaluate four solutions for mitigating read disturbance bitflips in the presence of ScaleDisturb and call for more research on the topic.

cs.CR↗

arXiv2018

Untethered microbot powered by giant magnetoelastic strain

Magnetic elastomers deform under a magnetic field, working as a soft actuator. Untethered microbot made of magnetic elastomers have great potentials in performing medical tasks inside human body as mini doctors. However, the lack of a highly deformable and efficient actuator strongly limits the development of magnetic microbots. In this paper, we developed an actuator of magnetic elastomer capable of large deformation strain by harnessing magnetic pull-in instability. We design three prototypes of untethered microbots by using this actuator: a robot grips objects with a large rotating angle, a robot navigates in a fluid channel and delivers drug, and a robot self-accelerates and quickly jumps up. The pull-in mechanism enables a new type of soft robot with fast response, remote wireless control and extremely high power density.

physics.app-ph↗