Browsing by Subject "non-volatile memory"

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    Userland CO-PAGER: boosting data-intensive applications with non-volatile memory, userspace paging
    (ACM, 2019-03) Li, Feng; Waddington, Daniel G.; Song, Fengguang; Computer Information and Graphics Technology, School of Engineering and Technology
    With the emergence of low-latency non-volatile memory (NVM) storage, the software overhead, incurred by the operating system, becomes more prominent. The Linux (monolithic) kernel, incorporates a complex I/O subsystem design, using redundant memory copies and expensive user/kernel context switches to perform I/O. Memory-mapped I/O, which internally uses demand paging, has recently become popular when paired with low-latency storage. It improves I/O performance by mapping the data DMA transfers directly to userspace memory and removing the additional data copy between user/kernel space. However, for data-intensive applications, when there is insufficient physical memory, frequent page faults can still trigger expensive mode switches and I/O operations. To tackle this problem, we propose CO-PAGER, which is a lightweight userspace memory service. CO-PAGER consists of a minimal kernel module and a userspace component. The userspace component handles (redirected) page faults, performs memory management and I/O operations and accesses NVM storage directly. The kernel module is used to update memory mapping between user and kernel space. In this way CO-PAGER can bypass the deep kernel I/O stacks and provide a flexible/customizable and efficient memory paging service in userspace. We provide a general programming interface to use the CO-PAGER service. In our experiments, we also demonstrate how the CO-PAGER approach can be applied to a MapReduce framework and improves performance for data-intensive applications.
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    Voltage Controlled Non-Volatile Spin State and Conductance Switching of a Molecular Thin Film Heterostructure
    (2021-05) Mosey, Aaron; Cheng, Ruihua; Joglekar, Yogesh; Decca, Ricardo; Vermuri, Gautum; Csathy, Gabor
    Thermal constraints and the quantum limit will soon put a boundary on the scale of new micro and nano magnetoelectronic devices. This necessitates a push into the limits of harnessable natural phenomena to facilitate a post-Moore’s era of design. Requirements for thermodynamic stability at room temperature, fast (Ghz) switching, and low energy cost narrow the list of candidates. Here we show voltage controllable, room temperature, stable locking of the spin state, and the corresponding conductivity change, when molecular spin crossover thin films are deposited on a ferroelectric substrate. This opens the door to the creation of a non-volatile, room temperature, molecular multiferroic gated voltage controlled device.