Brendan Gregg is the lead performance engineer at Joyent, where he analyzes performance and scalability for small to large cloud computing environments, at any level of the software stack. He is the primary author of DTrace (Prentice Hall, 2011), and coauthor of Solaris Performance and Tools (Prentice Hall, 2007), as well as numerous articles about systems performance. He was previously a performance lead and kernel engineer at Sun Microsystems, and also a performance consultant and trainer. He developed the DTraceToolkit and the ZFS L2ARC, and many of his DTrace scripts are shipped by default in Mac OS X and Oracle Solaris 11. His recent work has included performance visualizations.