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SIGMETRICS '98/PERFORMANCE '98 Proceedings of the 1998 ACM SIGMETRICS joint international conference on Measurement and modeling of computer systems
Experience with an adaptive globally-synchronizing clock algorithm
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MobiHoc '01 Proceedings of the 2nd ACM international symposium on Mobile ad hoc networking & computing
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Communications of the ACM
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IEEE Communications Letters
Nonuniform linear regression with block-wise sample-minimum preprocessing
IEEE Transactions on Signal Processing
Virtualize everything but time
OSDI'10 Proceedings of the 9th USENIX conference on Operating systems design and implementation
Clockscalpel: understanding root causes of internet clock synchronization inaccuracy
PAM'11 Proceedings of the 12th international conference on Passive and active measurement
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AdaSynch: A General Adaptive Clock Synchronization Scheme Based on Kalman Filter for WSNs
Wireless Personal Communications: An International Journal
The case for feed-forward clock synchronization
IEEE/ACM Transactions on Networking (TON)
Internet-scale IPv4 alias resolution with MIDAR
IEEE/ACM Transactions on Networking (TON)
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We present a detailed re-examination of the problem of inexpensive yet accurate clock synchronization for networked devices. Based on an empirically validated, parsimonious abstraction of the CPU oscillator as a timing source, accessible via the TSC register in popular PC architectures, we build on the key observation that the measurement of time differences, and absolute time, requires separate clocks, both at a conceptual level and practically, with distinct algorithmic, robustness, and accuracy characteristics. Combined with round-trip time based filtering of network delays between the host and the remote time server, we define robust algorithms for the synchronization of the absolute and difference TSCclocks over a network. We demonstrate the effectiveness of the principles, and algorithms using months of real data collected using multiple servers. We give detailed performance results for a full implementation running live and unsupervised under numerous scenarios, which show very high reliability, and accuracy approaching fundamental limits due to host system noise. Our synchronization algorithms are inherently robust to many factors including packet loss, server outages, route changes, and network congestion.