CODA：如何几乎零成本缓解列干扰？
CODA: How to Mitigate ColumnDisturb for (Almost) Free?
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中文总结 AI 辅助
研究如何缓解列干扰，提出CODA方法，通过CODA-E、CODA-F、CODA-G三个变体，大幅降低相邻计数器增量（ACI）率，减少12至1300倍，实现零性能和功率开销容忍列干扰。
中文摘要 AI 辅助
列干扰是一种新的数据干扰错误，攻击者行的激活会导致数百行之外的受害行（子阵列内比特翻转）以及相邻子阵列中的受害行（子阵列间比特翻转）发生比特翻转。子阵列粒度的解决方案（如SALT和REGA）可容忍子阵列内列干扰，但要容忍子阵列间列干扰，需用列干扰保护（CDP）扩展，这会因相邻计数器增量（ACI）使银行感知的激活增加到3倍，导致显著减速和刷新开销。本文提出CODA，一种列干扰缓解方法，大幅降低安全容忍列干扰所需的ACI率。它有三个变体：CODA-E通过利用相邻子阵列有需求激活时可跳过ACI的见解，将ACI减少2倍；CODA-F利用列干扰的持续时间对ACI进行部分增量，使ACI率降低2至16倍；CODA-G在多子阵列粒度上运行，为同一组内的相邻子阵列跳过ACI，进一步将总体ACI减少2至8倍。总体而言，CODA将ACI减少12至1300倍，实现零性能和功率开销来容忍列干扰。实验设置方面，通过对比不同方法在面对列干扰时的表现，验证了CODA的有效性。结论是CODA能有效缓解列干扰且几乎不产生开销，具有重要意义。
英文摘要
ColumnDisturb is a new data-disturbance error in which activations to an aggressor row cause bitflips in a victim row located hundreds of rows away (intra-subarray bitflips) and in victim rows in adjacent subarrays (inter-subarray bitflips). Intra-subarray ColumnDisturb can be tolerated by solutions (such as SALT and REGA) that operate at subarray granularity. However, to tolerate inter-subarray ColumnDisturb, such solutions must be extended with ColumnDisturb Protection (CDP), which performs additional {\em Adjacent-Counter Increment (ACI)} for the neighboring subarrays. The ACIs ensure that adjacent subarrays also undergo mitigation, even if they receive no demand activations. Unfortunately, because ACIs occur at a 200\% rate relative to demand activations, they effectively increase the activations perceived by the bank to 3x, which causes significant slowdowns (17\% at a TRHD of 500) and refresh overheads. The goal of our paper is to tolerate ColumnDisturb while incurring negligible overheads. We propose CODA, a ColumnDisturb mitigation that significantly reduces the rate of ACI required to securely tolerate ColumnDisturb. We present three variants of CODA. First, CODA-E (Evade), which leverages the insight that ACI can be skipped if the neighboring subarray receives a demand activation, and reduces ACI by 2x. Second, CODA-F (Fraction), which uses the timing duration of ColumnDisturb to do only a fractional increment for ACI, thereby reducing the rate of ACI by 2x-16x. Finally, CODA-G (Gangskip), which operates at multi-subarray granularity and skips ACI for neighboring subarrays within the same gang, further reduces overall ACI by 2x-8x. Overall, CODA reduces ACI by 12x-1300x, thereby making it possible to tolerate ColumnDisturb while incurring zero performance and power overhead.
