<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><div apple-content-edited="true" class="" style="orphans: 2; widows: 2;"><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div class="" style="margin: 0in 0in 0.0001pt;"></div><div class="" style="margin: 0in 0in 0.0001pt;"><span class="" style="font-size: 14px;"><b class=""><br class=""></b></span></div><div class="" style="margin: 0in 0in 0.0001pt;"><span class="" style="font-size: 14px;"><b class="">Mendel Rosenblum</b></span></div><div class="" style="margin: 0in 0in 0.0001pt;"><span class="" style="font-size: 14px;"><span class=""><i class="">Stanford University</i></span></span></div><div class="" style="margin: 0in 0in 0.0001pt;"><br class=""></div><div class="" style="margin: 0in 0in 0.0001pt;"><b class=""><font class="" style="font-size: 14px;"><br class=""></font></b></div><div class="" style="margin: 0in 0in 0.0001pt;"><span class="" style="font-size: 14px;"><b class=""><font class="">Tuesday, December 3, 2019 at 2:00 pm <br class="">Crerar 390</font></b><br class=""><br class=""><b class=""><font class=""><br class=""></font></b></span></div><div class="" style="margin: 0in 0in 0.0001pt;"><span class="" style="font-size: 14px;"><b class=""><font class="">Title:</font></b> </span><span class="" style="font-size: 14px;">Nanosecond-level Clock Synchronization in a Data Center</span></div></div></div></div><font size="4" class="" style="orphans: 2; widows: 2;"><br class=""></font><div class="" style="orphans: 2; widows: 2;"><b class=""><font class="" style="font-size: 14px;">Abstract:</font></b></div><div class="" style="orphans: 2; widows: 2;"><div class=""><span class="" style="font-size: 14px;">Computers connected by networks have long used protocols like Network Time Protocol (NTP) to adjust the clocks of the computers to show the same time of day. With machines connected by a high performance network in a data center, NTP can keep the clocks within a few hundred microseconds of each other, a clock skew that is fine for humans but not useful for distributed system software that can communicate between machines in a few tens of microseconds. In this talk I will describe the challenge of tightly synchronizing clocks in a data center and present Huygens, a new algorithm developed with my colleague Balaji Prabhakar’s </span><span class="" style="font-size: 14px;">research group that can synchronize data center clocks within few 10s of nanoseconds. Like </span><span class="" style="font-size: 14px;">NTP, Huygens requires no special hardware and simply exchanges messages between </span><span class="" style="font-size: 14px;">machines but uses a number of techniques that exploit the high-performance networks in </span><span class="" style="font-size: 14px;">data centers. The techniques include sending many more probe messages and then using </span><span class="" style="font-size: 14px;">sophisticated machine learning techniques and global knowledge to compute the clock </span><span class="" style="font-size: 14px;">adjustment operations to keep the clock synchronized.</span></div><br class=""></div><div class="" style="orphans: 2; widows: 2;"><b class=""><font class="" style="font-size: 14px;">Bio:</font></b></div><div class="" style="orphans: 2; widows: 2;"><span class="" style="font-size: 14px;">Mendel Rosenblum is a Cheriton Family Professor in the School of Engineering, Departments of Computer Science and Electrical Engineering at Stanford University where his research and teaching have focused on system software and distributed systems since 1992. In 1998 he helped transfer his research to industry by co-founding VMware. Mendel's work has numerous honors include receiving the ACM Software System Award (with several VMware colleagues), the ACM/SIGOPS Mark Weiser Award for innovation in operating system research, the IEEE Reynolds B. Johnson Information Storage Award (with John Ousterhout), the IEEE Computer Entrepreneur Award (with Diane Greene), and the ACM Doctoral Dissertation Award. He was the inaugural winner of the ACM Charles P. “Chuck” Thacker Breakthrough in Computing Award. He is a member of the National Academy of Engineering, the American Academy of Arts and Sciences, and ACM Fellow. Mendel has B.A. degree from the University of Virginia and M.S. and Ph.D. degrees from the University of California at Berkeley.</span></div><div class="" style="orphans: 2; widows: 2;"><span class=""><br class=""><font class="" style="font-size: 14px;"><b class="">Host:</b> Kate Keahey</font></span></div><div class="" style="orphans: 2; widows: 2;"><span class=""><font class="" style="font-size: 14px;"><br class=""></font></span></div><div class="" style="orphans: 2; widows: 2;"><span class=""><font class="" style="font-size: 14px;">PDF:</font></span></div><div class=""><span class=""><font class="" style="font-size: 14px;"></font></span></div></body></html>