Zhangxi Tan

I am currently a Founding Engineer at Pure Storage. I received my PhD from UC Berkeley in 2013. I was in the Parlab and ASPIRE project. Outside Pure, I spend my spare cycles helping the FireBox project. My research interests include large-scale computer and network systems, datacenter interconnect and storage system designs, computer architecture, massive-scale architecture simulation using FPGAs, and datacenter HW/SW co-design.

I was also with the RAMP and the RADlab project. I was co-advised by David Patterson and Krste Asanović.

CV (outdated)

Email: xtan at cs dot berkeley dot edu

Prior Research Projects

Traditional computer architecture research is incremental and boring. Building computer systems is an integral part of my research, as it is one of the best ways to valid assumptions. FPGAs are very interesting devices to implement architecture ideas, and run full software stacks. Againsting conventional wisdoms, we use FPGAs in an innovative way to look at large-scale full-system problems that could not be seen with traditional simulations.

DIABLO: datacenter-in-a-box at low cost

I built a cluster using 24 Xilinx Virtex 5 FPGAs, simulating a 3,000-node datacenter with a runtime-configurable interconnect. Each simulated server runs the full Linux operating system and unmodified production software such as memcached. DIABLO is a full-custom FPGA design based on RAMP Gold. Using DIABLO, we have successfully reproduced the memcached request latency long tail with 2,000 simulated nodes. To the best of our knowledge, DIABLO is the world's largest execution-driven datacenter simulator, and it works!

DIABLO is my PhD thesis research project. I built all hardware components from scratch myself, including a mulithreaded SPARC processor, switch/NIC, and memory/SERDES controllers. Throughout the process, we have developed the taxonomy of FPGA Architecture Model Execution (FAME), which systematically defines the foundation for architecture simulations using FPGAs.

RAMP Gold: an FPGA-based architecture simulator for multiprocessors

RAMP Gold allows rapid early design-space exploration of manycore systems. The RAMP Gold prototype runs on a single Xilinx Virtex-5 FPGA board and simulates a 64-core shared-memory target machine. We evaluate its performance using a modern parallel benchmark suite running on our manycore research operating system, achieving two orders of magnitude speedup compared to a widely-used software-based architecture simulator.

RAMP Gold is an open source project that has been downloaded for over 1,900 times since March 2010. It is currently used as a template design and a showcase for Systemverilog product development at Xilinx.

Research Internship at Microsoft Research Silicon Valley

I worked with Chuck Thacker, John Davis, Fang Yu, Lintao Zhang on several research projects using FPGAs, including building a novel circuit-switching datacenter interconnect and a parallel SAT solver accelerator(PSAT)

Misc

I am an avid eletric guitar player. I have my own youtube channel with my guitar work. I play rock/metal, country, and blues. I own several Fender strat/tele and Gibson Les Paul. I also mod my guitars and create custom gears for my dream tones.