Marek Denis works as a Software/Production Engineer at Facebook. He is currently part of the Active Network Monitoring team, where he spends days (and sometimes nights) designing and implementing systems that can keep up with Facebook’s massive infrastructure and provide clean and actionable signal for network on-calls. His work ranges from implementing modules in Linux kernel up to applying statistical models to find anomalies and outliers in endless streams of samples. Strongly believes in the motto “you can’t improve it if you can’t measure it”. Before joining Facebook he worked for 4 years at CERN in Switzerland as a Research Fellow. He designed and implemented federated identity systems for CERN’s private cloud.