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Solving Factual Inconsistency in Abstractive Summarization using Named Entity Fact Discrimination
Jeongwan Shin, Yunseok Noh, Hyun-Je Song, Seyoung Park
http://doi.org/10.5626/JOK.2022.49.3.231
Factual inconsistency in abstractive summarization is a problem that a generated summary can be factually inconsistent with a source text. Previous studies adopted a span selection that replaced entities in the generated summary with entities in the source text because most inconsistencies are related to incorrect entities. These studies assumed that all entities in the generated summary were inconsistent and tried to replace all entities with other entities. However, this was problematic because some consistent entities could be replaced and masked, so information on consistent entities was lost. This paper proposes a method that sequentially executes a fact discriminator and a fact corrector to solve this problem. The fact discriminator determines the inconsistent entities, and the fact corrector replaces only the inconsistent entities. Since the fact corrector corrects only the inconsistent entities, it utilizes the consistent entities. Experiments show that the proposed method boosts the factual consistency of system-generated summaries and outperforms the baselines in terms of both automatic metrics and human evaluation.
A Compression-based Data Consistency Mechanism for File Systems
Dong Hyun Kang, Sang-Won Lee, Young Ik Eom
http://doi.org/10.5626/JOK.2019.46.9.885
Data consistency mechanism is a crucial component in any file system; the mechanism prevents the corruption of data from system crashes or power failures. For the sake of performance, the default journal mode of the Ext4 file system guarantees only the consistency of metadata while compromising with the consistency of normal data. Specially, it does not guarantee full consistency of the whole data of the file system. In this paper, we propose a new crash consistency scheme which guarantees strong data consistency of the data journal mode by still providing higher or comparable performance to the weak default journal mode of the Ext4 file system. By leveraging a compression mechanism, the proposed scheme can halve the amount of write operations as well as the number of fsync() system calls. For evaluation of the performance, we modified the codes related to the jbd2 and compared the proposed scheme with two journaling modes in Ext4 on SSD and HDD. The results clearly confirm that the proposed scheme outperforms the default journal mode by 8.3x times.
Design and Implementation of a Log-structured Buffer Based on Non-volatile Memory
http://doi.org/10.5626/JOK.2018.45.11.1117
Next-generation non-volatile memory (NVM) technologies, such as PCM and STTMRAM, provide low latency, high bandwidth, non-volatility, and high capacity. Such NVMs are widely used and studied in the field of computer systems and databases for high performance computing. For example, recent researchers have used NVM for journaling buffers and database logging of file systems and have conducted many optimization studies accordingly. As a complement to existing work, this paper focuses on the atomic page update of applications. For example, in a data management application such as a database system, the atomicity of the pages is ensured by performing a redundant write operation with a temporary buffer in order to atomically update multiple pages. However, this redundant write operation can reduce the performance. Therefore, in this paper, we introduce a log-structured buffer manager (LSMB) to improve the performance while ensuring the consistency. LSBM updates the page to NVM by logging and provides buffering. In addition, if there are duplicated pages in the buffer, the old version of the page is removed to reflect only the latest page, which minimizes the I/O and write amount. Experimental results show that LSBM improves the performance of the application and reduces the total write amount.
Data Consistency-Control Scheme Using a Rollback-Recovery Mechanism for Storage Class Memory
Hyun Ku Lee, Junghoon Kim, Dong Hyun Kang, Young Ik Eom
Storage Class Memory(SCM) has been considered as a next-generation storage device because it has positive advantages to be used both as a memory and storage. However, there are significant problems of data consistency in recently proposed file systems for SCM such as insufficient data consistency or excessive data consistency-control overhead. This paper proposes a novel data consistency-control scheme, which changes the write mode for log data depending on the modified data ratio in a block, using a rollback-recovery scheme instead of the Write Ahead Logging (WAL) scheme. The proposed scheme reduces the log data size and the synchronization cost for data consistency. In order to evaluate the proposed scheme, we implemented our scheme on a Linux 3.10.2- based system and measured its performance. The experimental results show that our scheme enhances the write throughput by 9 times on average when compared to the legacy data consistency control scheme.
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