Woongki Baek

Energy-efficient computing is important in several systems ranging from embedded devices to large scale data centers. Several application domains offer the opportunity to tradeoff quality of service/solution (QoS) for improvements in performance and reduction in energy consumption. Programmers sometimes take advantage of such opportunities, albeit in an ad-hoc manner and often without providing any QoS guarantees.

Transactional memory (TM) provides mechanisms that promise to simplify parallel programming by eliminating the need for locks and their associated problems (deadlock, livelock, priority inversion, convoying). For TM to be adopted in the long term, not only does it need to deliver on these promises, but it needs to scale to a high number of processors. To date, proposals for scalable TM have relegated livelock issues to user-level contention managers. This paper presents the first scalable TM imp

Emerging byte-addressable non-volatile memory is considered an alternative storage device for database logs that require persistency and high performance. In this work, we develop NVWAL (NVRAM Write-Ahead Logging) for SQLite. The contribution of NVWAL consists of three elements: (i) byte-granularity differential logging that effectively eliminates the excessive I/O overhead of filesystem-based logging or journaling, (ii) transaction-aware lazy synchronization that reduces cache synchronization o

Energy-efficient computing is important in several systems ranging from embedded devices to large scale data centers. Several application domains offer the opportunity to tradeoff quality of service/solution (QoS) for improvements in performance and reduction in energy consumption. Programmers sometimes take advantage of such opportunities, albeit in an ad-hoc manner and often without providing any QoS guarantees. We propose a system called Green that provides a simple and flexible framework tha

Workload consolidation is a widely-used technique to maximize server resource utilization in cloud and datacenter computing. Recent commodity CPUs support last-level cache (LLC) and memory bandwidth partitioning functionalities that can be used to ensure the fairness of the consolidated workloads. While prior work has proposed a variety of resource partitioning techniques, it still remains unexplored to characterize the impact of LLC and memory bandwidth partitioning on the fairness of the conso

Transactional Memory (TM) simplifies parallel programming by supporting atomic and isolated execution of user-identified tasks. To date, TM programming has re quired the use of libraries that make it difficult to achieve scalable performance with code that is easy to develop and maintain. For TM programming to become practical, it is important to integrate TM into familiar, high-level environments for parallel programming. This paper presents OpenTM, an application programming interface (API) fo

The slotted-page structure is a database page format commonly used for managing variable-length records. In this work, we develop a novel "failure-atomic slotted page structure" for persistent memory that leverages byte addressability and durability of persistent memory to minimize redundant write operations used to maintain consistency in traditional database systems. Failure-atomic slotted paging consists of two key elements: (i) in-place commit per page using hardware transactional memory and

Heterogeneous embedded systems have surfaced as a promising solution for accurate and efficient deep-learning inference on mobile devices. Despite extensive prior works, it still remains unexplored to investigate the system-software support that efficiently executes inference workloads by judiciously considering their performance and energy heterogeneity, communication overheads, and constraints. To bridge this gap, we propose MOSAIC, heterogeneity-, communication-, and constraint-aware model sl

Transactional Memory (TM) simplifies parallel programming by supporting atomic and isolated execution of user-identified tasks. To date, TM programming has re quired the use of libraries that make it difficult to achieve scalable performance with code that is easy to develop and maintain. For TM programming to become practical, it is important to integrate TM into familiar, high-level environments for parallel programming. This paper presents OpenTM, an application programming interface (API) fo

Heterogeneous memory systems that comprise memory nodes based on widely-different device technologies (e.g., DRAM and nonvolatile memory (NVM)) are emerging in various computing domains ranging from high-performance to embedded computing. Despite the extensive prior work on architectural and system software support for heterogeneous memory systems, relatively little work has been done to investigate the OS-level memory placement and migration policies that consider the bandwidth differences of h

Transactional Memory (TM) is a promising technique that simplifies parallel programming for shared-memory applications. To date, most TM systems have been designed to efficiently support single-level parallelism. To achieve widespread use and maximize performance gains, TM must support nested parallelism available in many applications and supported by several programming models.

Memory bandwidth is a highly performance-critical shared resource on modern computer systems. To prevent the contention on memory bandwidth among the collocated workloads, prior works have investigated memory bandwidth partitioning techniques. Despite the extensive prior works, it still remains unexplored to characterize the widely-used memory bandwidth partitioning techniques based on various metrics and investigate a hybrid technique that employs multiple memory bandwidth partitioning techniqu

Heterogeneous multi-processing (HMP) is rapidly emerging as a promising solution for high-performance and low-power computing. Despite extensive prior work, system-software support for self-adaptive multithreaded applications has been little explored in the context of HMP. To bridge this gap, we propose HARS, a heterogeneity-aware runtime system for self-adaptive multithreaded applications. HARS continuously monitors the application performance and dynamically adapts the system state to enhance

Energy-efficient computing is important in several systems ranging from embedded devices to large scale data centers. Several application domains offer the opportunity to tradeoff quality of service/solution (QoS) for improvements in performance and reduction in energy consumption. Programmers sometimes take advantage of such opportunities, albeit in an ad-hoc manner and often without providing any QoS guarantees. We propose a system called Green that provides a simple and flexible framework tha

Emerging byte-addressable non-volatile memory is considered an alternative storage device for database logs that require persistency and high performance. In this work, we develop NVWAL (NVRAM Write-Ahead Logging) for SQLite. The contribution of NVWAL consists of three elements: (i) byte-granularity differential logging that effectively eliminates the excessive I/O overhead of filesystem-based logging or journaling, (ii) transaction-aware lazy synchronization that reduces cache synchronization o