Founded Conectiva in 1995, a brazilian company that specialized in Linux services and published a Linux distribution.
Contributed with the Linux kernel maintaining legacy protocols such as IPX, LLC, Appletalk. Refactored the TCP/IP stack to reuse non TCP specific parts with other transport protocols. Implemented the Linux DCCP stack.
Created and maintains the dwarves tools, including pahole, a tool to help in optimizing data structures, used in projects such as the Linux Kernel, glibc, KDE, xine and many others.
Currently the maintainer of the Linux 'perf' observability (profiling, tracing, debugging, etc) tools. Works for Red Hat since 2007.